Researching Religion on the WWW: Identifying an Object of Study for Hinduism

As a result of the increasing importance of the Internet, it is imperative that social researchers subject online phenomena to investigation and analysis. However, online methodology is largely in its infancy which means that researchers are, as yet, ill-equipped to approach this important task. In this article – focusing upon researching religion online – I outline problems regarding researching the WWW and put forward one way of identifying an object of study which can then be subjected to further analysis. Hinduism on the WWW is used as an example, and the discussion of my methodological approach applied to this area demonstrates that the identification of the object of study is actually bound up with the processes that occur online. This means that details of the area under investigation are revealed and that preliminary analysis of the situation can occur at the same time that the object of study is being identified. After this demonstration I challenge the claim that because the WWW is constantly changing, online research can only constitute a snapshot in time, and conclude the article with a plea to other researchers to share their methodological approaches to researching online phenomena in order that effective online research methods will be able to be developed.

Introduction
In this article I consider problems surrounding researching the World Wide Web (WWW) 1 and suggest one way in which an object of study can be obtained in order to study religion on the WWW -in this case Hinduism. The focus is upon Hinduism because the analysis of the online situation was an essential part of a larger research project that I conducted which examined the relationship between Hinduism and the Internet. 2 For the study of online phenomena to proceed effectively, an object of study must be identified using methods that are rigorous and which have a clear rationale behind their use. Using unsystematically selected data as the basis for analysis -which means both that the validity of what is being studied is left unclear and that replication in the future is difficult -is insufficient. A rigorous research design is of paramount importance because not only is the online situation important in itself, but the online and the offline are not constitutive of a duality and processes that occur in the traditional 'offline world' affect the online situation and vice versa. This is becoming more significant as a result of increasing use of the Internet and leads Barker to remark that 'any student of religion -or, indeed, of contemporary society -will ignore [the Internet] at his or her peril' (Barker 2005: 81). Echoing this, Flory claims that religion on the WWW is 'here to stay [and therefore] scholars of religion…had better take that reality seriously as it will undoubtedly change both the practice of _____________________________________________________________________________________________ Correspondence: heinz.scheifinger@ubd.edu.bn ISSN: 1748-0612online DOI: 10.4256/mio.2008.0004 "real-world" religion and our approaches to it' (Flory 2005: 365). Bunt makes a similar point and concludes that 'over time it is anticipated that the Internet will form an integral component of conventional fieldwork' (Bunt 2003: 209).
It is therefore clear that effective online research methods -which are still in their infancy (Wakeford 2004: 34, Hine 2005a: 1) -need to be developed. Concerning the study of religion online this is perhaps especially important because Dawson, one of the prominent scholars in the field, notes that 'I know of no efforts to systematically gauge the degree of real religious interactivity happening online' (Dawson 2005: 30). It is my hope that the process that I outline in order to enable an area of the WWW to be researched will encourage others to share their experiences of researching the WWW and that my methods will be able to be improved and built upon -a crucial undertaking in the light of the above comments.
Because my study upon which this article is based included a general investigation of the relationship between religion and the Internet, the initial discussion that I offer regarding researching the WWW references a number of studies that were concerned with researching religion online. However, the main points that I make also have generalisability to researching other areas on the WWW and are not just restricted to religion. Similarly, in my explanation of the process that I undertook in order to identify an object of study for Hinduism on the WWW, it should be appreciated that the process can be used to study the online presence of any religion. The discussion which then follows regarding the object of study provides a clear example that the process can be highly beneficial in that it can both tell us a great deal about the subject under consideration and can provide the starting point for further analysis.

Volume of websites
One significant problem in researching the WWW is the sheer number of websites (for example, performing a Google search on 29 March, 2007 using the search term 'Hinduism' resulted in 9,480,000 results 3 ) which means that it is impossible for a single researcher to investigate even a significant proportion of them (see Bunt [2003: 7]; Dawson [2005: 15] and Apolito [2005: 14]). It is also not possible to gain a fully representative sample because the amount of websites is growing at such a rate that search engines are unable to keep track of them. Dreyfus noted in 2001 that the WWW was growing at a rate of at least a million pages a day (Dreyfus 2001: 8) and he quotes a New York Times article from 2000 which states that 'There are now more than one billion Web pages and, according to some experts' calculations, the number has been doubling once every eight months' (Dreyfus 2001: 96). Therefore, when a search engine is used, the results that it produces omit many websites. In fact, according to Dreyfus, it is estimated that search engines 'can recall at most 2 per cent of the relevant sites' (Dreyfus 2001: 23) and that those in the search engine industry believe that '"30 per cent is all one can hope for"' (Dreyfus 2001: 25).

Website boundaries and related issues
What actually constitutes a website and a webpage is also an issue that needs to be addressed in order to carry out empirical research. According to Buckley and Clarke, the term 'website' refers to 'a collection of related documents' on the WWW and can be contrasted with the term 'webpage' which refers to 'a single document' (Buckley and Clarke 2004: 530 website is indeed a collection of related documents, for practical purposes its homepage can helpfully be used to refer to the website as a whole. Thus, for example, marketleap.com 4 is technically a homepage but also refers to the overall website which incorporates other webpages such as marketleap.com/linkpopularity. In addition to this, some webpages within websites are, effectively, homepages of other distinct sections and because of this; these webpages should also be referred to as websites. For example, religioustolerance.org/hinduism is classified in my study as a website even though technically it is part of the larger religioustolerance.org. Although problems of definition can be overcome, there are still other issues that need to be considered. One problem concerns the boundaries of websites. This is because of the interconnected nature of the WWW which means that websites are fluid to an extent. For example, a website will almost always contain links to websites of other organisations and/or individuals and therefore it is not always clear where one website ends and another begins. However, the homepage of a website can be identified and the general nucleus of the website can then be ascertained. Furthermore, I believe that in general, it is possible to identify the boundaries of websites if they are analysed carefully. Indeed, such an investigation is an important part of research and can give an indication of links between different organisations. Other related problems are identified by Bowie. In her consideration of hypertext (image or text that facilitates navigation to other webpages), amongst other things, she identifies 'getting lost in the links' and the 'possibility of missing information' as being problematic (cited in Nayar 2004: 115). Again, careful research can minimize such problems but the sheer size of some websites does mean that the possibility of missing information is always a danger.

Identification of those responsible for websites
A further research problem concerns the identification of who is responsible for a website as this is not always made explicit. However, unless the website is particularly obscure, it is usually possible to identify who is behind it. Indeed, in many cases those behind websites wish to make themselves known in order to further their interests. In some cases though, the situation is not so cut and dried, and organisations may wish not to make explicit their ideological position and have specific reasons for this. As in the case of the identification of website boundaries, this difficulty is not really a methodological problem as such, as the intention of organisations not to make explicit their ideology or links with other organisations is of sociological interest in itself.

Innovative multiple methods
As online research methods are undeveloped and non-standardised, it is left up to the researcher to devise a research strategy which she or he feels will give rise to productive research. Examples where new and different methods used to research online phenomena are revealed in sociological studies of religion and the Internet include Mayer (2000), Campbell, H. (2004), Campbell, R.A. (2004), Dawson and Hennebry (2004), Helland (2004) and Højsgaard (2005). Such studies can be distinguished from studies of religion and the Internet which do not attempt to formulate or use rigorous methods when researching the contents of the WWW such as those by Beckerlegge (2001), Bunt (2003, Brasher (2004) and Apolito (2005) (which still contribute to our knowledge of issues surrounding religion and the Internet).
What is apparent from the first set of studies is that the respective researchers have had to be creative in formulating their research methods and there are wide differences between the various methodological approaches. However, in his review of Religion Online: Finding Faith on the Internet (from which all of the 2004 studies in the first list are taken), Flory (2005) argues that the lack of a unified methodological approach _____________________________________________________________________________________________ Correspondence: heinz.scheifinger@ubd.edu.bn ISSN: 1748-0612online DOI: 10.4256/mio.2008.0004 is one of the volume's shortcomings and notes that there is no mention of methodology in the editors' introductory essay. Furthermore, he argues that methodological statements are generally inadequate in the subsequent chapters (Flory 2005: 364-365). However, the methodological statements provided in the studies that I have selected are actually far more comprehensive than in many others. This is not to say, though, that there should not be an improvement in this respect. Furthermore, the fact that these studies are criticised for their methodology despite the fact that they are better than others in this respect emphasises that methodological issues need to be considered further. Therefore, I fully agree with Flory's assertion that much work needs to be done concerning online methodology, although I am unconvinced when he says that 'a systematic methodological approach is necessary' (Flory 2005: 364 [my emphasis]).
Because of the diversity of studies of religion and the Internet, I believe that different methodological approaches to researching the WWW are desirable and there is little to be gained in any attempt to achieve a unified methodological approach. Højsgaard and Warburg highlight the diversity of the methodological approaches featured in their 2005 edited volume concerning religion and the Internet and agree with my view that multiple methodologies are desirable and necessary (Højsgaard and Warburg 2005: 8-9). Hine also advocates multiple methodologies when she notes that diverse research methods are needed. In the introduction to her edited volume dealing with online methodology, she notes that the respective authors in the book were involved in 'working out a situated response to the research question they wished to address, appropriate to the conditions which they found in context' (Hine 2005a: 1) and stresses the need for 'innovation' 5 in formulating online research methods (Hine 2005a: 9; see also 2005b: 109). Jankowski and van Selm also advocate 'multiple methods' (Jankowski and van Selm 2005: 206), as does Guimarães Jr. (2005: 141).
The need to formulate suitable research methods provides a good challenge not only to the researcher, but also to the consumer of the research. If the rationale behind the research methods which are considered to be productive by the researcher is made explicit, the audience can decide whether these methods are largely unproblematic and productive. When this occurs, all carefully thought out research methods, even if they are not perfect, are likely to contribute to more coherent ways of researching the online situation in the future. Different types of research methods can be built up and drawn upon, albeit with constant modification. Hine also makes this point when speaking about the studies in her afore-mentioned edited volume (Hine 2005a: 1-2). Importantly, rather than adapting conventional methods which may be ill-suited to researching the WWW, new methods which suit the online situation need to be formulated by researchers. Sanders reaches a similar conclusion to this and asserts that: 'transferring a methodological procedure from a traditional context to the virtual environment is not necessarily effective' (Sanders 2005: 73), although Hine warns that not all conventional research methods should be jettisoned (Hine 2005a: 2).

The methodological approach used to investigate Hinduism on the WWW
As has been emphasised, in my quest to find out just what was on the WWW concerning Hinduism, there were no established research methods that I could utilise. Instead, it was necessary to design a new way to conduct the investigation. Again it should be emphasised here that the main obstacle is the vast number of relevant websites. Despite this, as I will demonstrate, I am able to identify an object of study which allows a sociological investigation to proceed in a number of different ways.
My approach is unusual in that, in the light of the problems regarding the number of websites, I decided that the most productive starting point would be to initially adopt an empathetic position and consider what a _____________________________________________________________________________________________ Correspondence: heinz.scheifinger@ubd.edu.bn ISSN: 1748-0612online DOI: 10.4256/mio.2008.0004 general seeker might encounter when searching the WWW for 'Hindu-related websites'. 6 Furthermore, the approach goes beyond methodology as traditionally conceived and is inherently tied up with the processes and dynamics that actually produce the WWW (this type of methodology is mentioned by Hine [2005b: 111] and is discussed and utilised by Beaulieu [2005] and Park and Thelwall [2005]). Because of this, in addition to merely identifying an object of study, the approach allows a number of important aspects of it to be discovered and subjected to analysis at the same time. This will be demonstrated in due course.
Beginning with the assumption, backed up by research, that a general seeker would likely start by typing 'Hinduism' into a search engine 7 (Helland reports that according to the GVU 10 th WWW User survey; 'most persons find the web sites they are looking for by linking through from one site to another by using a search engine' [Helland 2002: 299]), I did this myself on two occasions approximately one year apart using a number of different search engines. With the help of mapping software, I then followed the links from the 'prominent websites' (a term which will be explained below) in the top ten of the search engine rankings to other websites. All of these websites (and their links) constitute the object of study -which I refer to as 'the general area of Hinduism on the WWW' -that can then be subjected to analysis. For example, the websites, the organisations/individuals behind them, and the links between websites, can all be considered, as can the differences between the results from the two searches.

The general area of Hinduism on the WWW
The prominent websites which give rise to the general area of Hinduism on the WWW are the key to an analysis. Not only are they encountered when searching for Hinduism using a search engine, but they are also important because their prominence is such that they are continually encountered when searching the WWW for Hindu-related websites. The links between websites are extremely important in this respect. Aside from the number of links which can affect a website's search engine ranking, it is also important to note that the actual links between websites are highly significant. One reason why this is the case is that links from prominent websites, where they extend to other websites not belonging to the same organisation, are often to the other websites which are also prominent. Therefore, because linkages are related to search engine rankings, this results in a positive feedback system whereby prominent websites become even more prominent. This contributes to the situation whereby there are a relatively small number of organisations/individuals that have prominent websites.
Furthermore, when the prominent websites link to websites that are not prominent, they tend to link to websites which approach Hinduism from a similar viewpoint. In addition to this, links from 'objective' organisations (such as the BBC) often lead to websites of those organisations that are prominent on the WWW and this not only increases the credibility of a website, but can also actually help in its search engine ranking. For example, keyword relevance is not the only criterion used by the popular Google search engine in order to rank websites. According to Google, in addition to text analysis, a major way to determine the value of a website is through the number of links there are to the website. However, Google staff also analyse the websites which offer links and assign them a level of importance. Therefore, a link from a BBC website is considered to be more significant than a link from an obscure website and this contributes to the website appearing higher up in the Google search engine rankings. This also means that if an organisation or individual creates a large number of bogus links to its website then this will have no real impact on its search engine ranking (see google.com/technology) and instead the key is to 'offer good content and features' to naturally increase links to the website (see marketleap.com/linkpopularity). The complex way in which the prominent websites are linked to each other is bewildering at first, but after research over a period of months, the general area of Hinduism on the WWW can be comprehended and subjected to analysis. Although a discussion of the prominent websites on the WWW and their relationships to each other gives a good impression of Hinduism on the WWW, it is important to emphasise that my method deliberately does not provide a representative sample of Hindu-related websites which would need to include websites that do not feature in the top ten of search engine rankings. As mentioned above, it is actually impossible to obtain a truly representative sample of websites because there is a large number that are not even catalogued by search engines. If this was ignored and the websites identified by various search engines were deemed to be acceptable sampling frames, a quasi-random sampling method (see e.g. McNeill 1990: 37) (refined by giving weight to higher ranked websites) could be applied to the sampling frames a number of times over a given period. This would result in samples of websites which would possibly be more representative of Hindu-related websites on the WWW than those that constitute the general area of Hinduism on the WWW. However, it is my intention to identify those websites that would be encountered by a general seeker and therefore any attempt to achieve a sample of websites which is more representative would actually be undesirable.
A related point which is also worth noting is that because I am only interested in identifying the general area of Hinduism on the WWW and not in obtaining a representative sample, important issues regarding the way that commercial search engines work and the way that owners of websites may be able to manipulate rankings are no threat to the identification of a valid object of study. Similarly, the fact that some individuals/organisations have obtained 'memorable domain names' (Bunt 2000: 129) (e.g. hindu.org) which can increase 'traffic' to their websites and consequently affect search engine rankings is also of no concern in this context. There might also be the argument that many individuals just go straight to websites that they are already aware of and do not use search engines. However, again, because I am seeking to identify the general area of Hinduism on the WWW, such a criticism does not render my approach invalid.
Not only does an investigation of the general area of Hinduism on the WWW provide a picture of the online situation. As emphasised at the outset of this article, it is also important to realise that the online situation can affect what occurs offline. For example, those Hindu organisations that are prominent on the WWW are not necessarily those that are the most prominent in the 'offline world'. However, it is the very fact that a group's online presence is not comparable with their offline presence that is significant because, as I discovered during my research, a strong online presence can lead to increased credibility and influence in the 'offline world'i.e. previously relatively insignificant groups have the potential to become significant as a result of their presence on the WWW.
I will now present in detail the process that I undertook in order to identify 'the general area of Hinduism on the WWW':

Search engine results
On 13 November, 2004 and 26 October, 2005 8 I typed 'Hinduism' into five popular search engines. The following tables of results show the websites that were ranked in the top ten. Cells containing those websites of organisations or individuals that have websites that appear at least three times in either of the two searches, are coloured. This makes it clear to see that there are a small number of organisations/individuals whose websites populate the top ten across the different search engines. These websites are the 'prominent websites' (aside from search engine ranking, three further indicators [see below] are used to justify this categorisation).

Discussion of search engine results tables
The two tables show that there was very little difference in the results between the two search dates and that the prominent websites have largely been able to maintain their position during the period of the research. Apart from religioustolerance.org/hinduism, the websites from this organisation are the only ones to appear in the top ten of all five of the featured search engines on both of the search dates. Furthermore, in some rankings more than one website from this organisation appears. In 2004 the websites appeared third, fifth and sixth in the Google search engine rankings and in 2005 they appeared fourth, sixth and seventh. In the Yahoo! rankings the websites had gone down from two appearances (at fourth and ninth) to one appearance at seventh. In the AlltheWeb rankings the one SSC website remained (at seventh place compared to fourth). In the Ask Jeeves rankings there were three websites which occupied the same positions (fifth, sixth and eighth) although the order of the specific websites had changed, and in the MSN rankings there was an increase in the number of SSC websites that appeared. In 2004 there was one in second position and one in tenth, while in 2005 there were websites at numbers two, seven and eight.
Alone, these statistics might suggest that there are a relatively small number of organisations that inhabit the general area of Hinduism on the WWW. However, this is only the tip of the iceberg. When a further three indicators are used and the results investigated, I am able to fully demonstrate that certain organisations were able to colonise the general area of Hinduism on the WWW during the period of research. This means that those who were just seeking general information about Hinduism would be certain to come across those websites of a relatively few organisations. Furthermore, even those who choose to look up specific websites are likely, through links, to end up at a website from one of these organisations. Therefore, the three further indicators that I use demonstrate why I classify these websites as 'prominent' websites. The three indicators are 'search engine saturation', 'link popularity', and the links that are revealed using 'TouchGraph' mapping software which can then be investigated.

'Search engine saturation' and 'link popularity'
'Search engine saturation' and 'link popularity' can be ascertained through software available at marketleap.com. 10 'Search engine saturation' refers to the number of times that a website address appears in a search engine's index. Although it is not necessarily related to search engine ranking, it is clear that if a website 'saturates' a search engine, this gives an indication of its prominence (see marketleap.com/saturation). 'Link popularity' refers to the number of links from other websites that a website has, and, as mentioned above, this affects a website's search engine ranking. However, in addition to search engine rankings and 'search engine saturation', it also gives a partially independent indication of a website's prominence. 'Search engine saturation' and 'link popularity' checks 11 for the already identified prominent websites were carried out on 11 November, 2005 with the following results: 12  These tables demonstrate that among the prominent websites there are two organisations (the SSC and the HSC) that have been far more successful than the others in saturating search engine indexes with their websites. The reason why some websites have a 'search engine saturation' figure of less than ten is that they are actually parts of much larger websites which do not deal exclusively with Hinduism. However, as explained above, to all intents and purposes these are also homepages of Hindu-related websites and thus can be comfortably referred to as 'websites'. The websites with higher 'search engine saturation' figures are the actual homepages which form the nucleus of the respective websites and which represent the overall website as a whole. The fact that those websites with such a small 'saturation' figure are still prominent Hindu-related websites further demonstrates the significance of those that have a high level of 'saturation'. Websites of the SSC and the HSC also have by far the highest level of 'link popularity' out of all of the prominent websites, which again emphasises the pre-eminent position of these organisations.

'TouchGraph' link maps
Now that the 'link popularity' of the prominent websites has been shown, I will demonstrate how it is possible to explore the links from these websites in more detail. Links 13 are revealed through the use of 'TouchGraph' software 14 which graphically shows links between websites (see figs. 1 and 2), 15 and these links can then be followed manually and subjected to analysis. I produced the website linkage 'maps' ('touchgraphs') on 26 October, 2005. I will now present two 'touchgraphs' as examples and show how following the links can help to build up a picture of the general area of Hinduism on the WWW: Fig. 1 'TouchGraph' for hindunet.org hindunet.org is a huge portal website offering access to a large amount of Hindu-related material. It is part of the Global Hindu Electronic Network (GHEN) which is a project of the Hindu Students Council (HSC). hindunet.org links to other HSC websites, websites of associated organisations, and websites of organisations which share a similar ideological position to the HSC. There are also links to other websites that appear in the search engine results tables. For example, in one 'direction' hindunet.org links to hscnet.org (partially obscured on the 'TouchGraph') which is the main website of the HSC. hscnet.org then links directly to hindukids.org which is a teaching resource for children that is part of the GHEN. hindukids.org links to rss.org which is the website of the Rashtriya Swayamsevak Sangh (RSS), the fundamentalist Hindu organisation that the HSC is associated with. hscnet.org also links to ekalvidya.org (which is concerned with social development in rural areas of India), to hssworld.org (the website of the US branch of the fundamentalist Hindu Swayamsevak Sangh [HSS]), to sanskrit.gde.to (a resource for learning Sanskrit) and to hindu-universiy.edu (the website of the Hindu University of America). In another 'direction', hindunet.org links to hindu.org (a directory of Hindu-related websites) which is one of the three websites of the SSC. From there, links extend to the other two SSC websites: himalayanacademy.com (the SSC's main website) and hinduismtoday.com (an online version of the SSC's magazine). From hindu.org there is a link to hindulinks.org (primarily a directory of mandirs [Hindu 'temples']) which is another website of the HSC. hindu.org also links to hinduism.co.za (a huge resource containing information about Hinduism) -another of the prominent websites. A link is shown to part of the overall religioustolerance.org website which is indicative of a close link to religioustolerance.org/hinduism (another website providing information about Hinduism) which appears in the rankings of every search engine in both of the search engine results tables. 16 This 'TouchGraph' alone, clearly shows that the prominent websites are linked to each other and that there are also other links between websites of organisations that have similar ideologies.

Fig. 2 'TouchGraph' for himalayanacademy.com
When the SSC's main website himalayanacademy.com is used as the central node in a 'TouchGraph', not only are the unsurprisingly clear links with the other websites of the SSC shown, but the afore-mentioned links to the HSC websites in more than one direction are also clearly demonstrated. There are also links to hinduism.co.za and atributetohinduism.com (a website set up by an individual offering information about Hinduism) -yet another of the prominent websites.
In addition to a consideration of the links originating from the HSC's hindunet.org and the SSC's himalayanacademy.com, I produced 'touchgraphs' for all of the other prominent websites which did not  17 This confirmed that the prominent websites are closely linked to each other. The full analysis of these links between the websites completes the process which results in the identification of the object of study. This analysis is not included here because the two examples provided above are able to demonstrate the efficacy of the method and additional detail is unnecessary.

Further analysis
The methodological approach outlined in this article is very different from that employed in other research projects in which the method of data collection is usually a separate tool from the data that is collected and does not figure as part of the analysis itself. Instead, the process that allows this object of study to be identified also forms part of the analysis. For example, as a result of the procedure outlined above, I am able to make an important claim: not only are there certain websites which appear high in search engine rankings (and may have a high level of 'search engine saturation' and 'link popularity'), but these websites link to each other. This dense pattern of reciprocal links helps to explain the general area of Hinduism on the WWW which, as has been demonstrated, has been largely colonised by a small number of organisations -a development which is significant given the fact that the online situation can affect what occurs offline.
In turn, this provides the starting point for further analysis of the relationships between organisations and the activities of certain groups. For example, within the general area of Hinduism on the WWW it is clear that, due to their prominence, the websites of the SSC are very important. I have shown that during the period of the research this organisation's websites appeared frequently in the search engine rankings. Furthermore, even if one of the non-SSC prominent websites were to be initially chosen by a general seeker of Hindu resources online, it is highly likely that they would be led to one of the SSC websites because of the way that the prominent websites are linked. This invites further analysis. For example, I have mentioned that the SSC is responsible for hindu.org which is a directory of Hindu-related websites -and a consideration of this website confirms the SSC's strong position online. This website is easily accessible and does not overtly appear to be linked to a specific group, and therefore there is no reason to suggest that the links that it offers will not be followed. An important point concerning this, however, is that these links are provided with commentary reflecting the views of the SSC. This is an area that can be further investigated, the relevance and importance of which would never have come to light if it were not for the identification of the general area of Hinduism on the WWW.
Furthermore, once the object of study has been identified, the situation can then be analysed in the light of various sociological theories. For example, in my overall study of the relationship between Hinduism and the Internet referred to in this article, the online situation and the uses of the Internet by the organisations/individuals with the prominent websites were able to be further investigated using the theoretical approaches of globalisation and rational choice. A more detailed picture of the general area of Hinduism on the WWW can also be built up through a consideration of the characteristics of all of the aforementioned prominent websites that are constitutive of this, and this information can lead to further avenues of research.

A note concerning flux
The WWW is in a constant state of flux. For example, website content changes and new websites appear while others disappear. In addition to this, as would be expected, and as I have demonstrated above, the positions of websites in the search engine rankings change over time. Because of this, there is the common belief that this poses a great problem for online research. However, flux is an inherent characteristic of the WWW and is Because of the constantly changing nature of the WWW it is sometimes argued that research can only provide a snapshot in time of the online situation. While this is true to an extent, the idea of a snapshot can be misleading -it gives the impression that if research were carried out, say, six months later, research results would be markedly different and that, apart from providing a snapshot in time, this would render the original research as being of little importance. I believe that although the online situation is indeed constantly changing, the speed and extent of this change is largely exaggerated, at least concerning Hinduism, and therefore it is not necessarily the case that only a snapshot in time is provided. For example, the two online searches were conducted about a year apart from each other. Although there were changes (and it is such changes that are actually sociologically significant!), the overall situation largely remained the same. Furthermore, while content of many websites obviously changes, in some cases change is minimal. In addition to this, even when content does change, website ethos usually remains consistent. For example, some content of the SSC's main website changes almost daily, but a large amount of the content remains the same and the ethos of the websites of the SSC does not change radically over time. In short, it is wrong to suggest that online research can only provide a snapshot in time. This claim is supported by Dawson who, writing in 2005, argues that since 1998, although there has been an increase in religious websites, 'the landscape of virtual religion has not changed much' (Dawson 2005: 30). Further support comes from Cowan (2005: 259) and O'Leary (2005: 39-41) who note that the nature of online Pagan rituals did not alter significantly between 1996 and 2005.
However, it is important to appreciate that change is occurring constantly. For example, in the future it is certainly likely that there will be significant changes in the online situation. If replicable research methods are used though -such as those outlined here -future studies will be able to identify such changes. This is demonstrated by an investigation that I undertook on 29 March, 2007 which showed that the websites of the SSC in the general area of Hinduism on the WWW became far less prevalent than was previously the case.
Against the objection that the WWW is in a constant state of flux and that this means that studies are mere snapshots in time, I would also point out that no area of social life is fully static. For example, Selltiz et al, when talking about rigorous survey design which aims to have a high degree of reliability, state that 'independent but comparable measures of the same object (or attitude, or whatever) should give similar results' but then add that 'provided of course, that there is no reason to believe that the object being measured has in fact changed between the two measurements' (Selltiz et al. 1962: 148). Then there is always the attendant problem of distinguishing true change from apparent change highlighted by unreliable research methods (Bohrnstedt 1983: 80). This demonstrates that pointing to the online situation and saying that it cannot be adequately researched because it is constantly changing is unfair -traditional offline studies also have to deal with issues concerning the object of study changing.
There are other reasons why I believe that an effective study goes beyond merely being a snapshot in time and these are unrelated to my arguments above. For example, my online research enabled me to directly consider contemporary Hinduism in a number of different ways which are not solely dependent upon the online situation as it currently stands. Furthermore, I was able to demonstrate that a consideration of the online situation and Hinduism in the light of a number of sociological theories also contributes to the understanding of contemporary Hinduism. In doing this, I was also able to assess the strengths and weaknesses of these sociological theories and in some cases I was able to suggest revisions of the theories as a result of the new situation that has arisen as a result of the Internet. Again, insights are not just dependent upon the current online situation. Therefore, whilst the changing nature of the WWW is fully acknowledged, it is not regarded as being a barrier to online research.

Conclusion
In this article I have attempted to show that despite the huge number of websites on the WWW and other associated problems, an object of study can be identified which allows a fruitful sociological investigation of online phenomena to proceed. Importantly, the methods used in the identification of the object of study can be replicated and therefore future researchers will be able to identify any significant changes in the online situation. Furthermore, the methods outlined here allow the online presence of different religions to be compared.
The discussion of my methodological approach applied to Hinduism on the WWW has also demonstrated that the identification of the object of study is tied up with the processes that occur online. This means that further details are also revealed and that analysis can occur at the same time that the object of study is being identified. As stated at the outset of this article, the process that I propose is but one way of approaching the task of obtaining an object of study which allows productive online research to proceed and hopefully other techniques will be put forward by fellow researchers. In this way, different research methods will be able to complement each other and online methodology will be able to be developed.


Holonic Production System to Obtain Flexibility for Customer Satisfaction

The Holonic Production System (HPS) can be a valid choice to overcome the problems of traditional production sys-tems’ architectures, thanks to its capability to adapt and react to changes in the business environment whilst being able to maintain systemic synergies and coordination. The HPS is made of holons seen as functional production units which are simultaneously autonomous and cooperative. Although the holonic approach could represent a valid solution in order to pursue the necessary levels of agility of production systems, they have been scarcely implemented in practice and even less studied from a business studies perspective. The purpose of this discussion paper is to show the benefits of further research on cases of implementation of HPS from a business organization studies perspective. Very little re-search on this topic has been done outside the field of business engineering and computer science; the study of this topic from a different perspective can shed the light on new aspects and new applications of the theory.

Introduction
Mass production showed its effectiveness in stable environments and with continuous growth trends 1 until the end of the 80's. Since the beginning of the 90's, it has begun to show its weaknesses due to the growing instability of business environments and of systemic complexity. The spread of Internet made it possible for firms the use of a low cost, worldwide extended, informative infrastructure which can bring profound changes in the market. In mature markets it is necessary to supply a wide variety of products in order to adhere to the need of customers whose role has changed from "consumer" to "prosumer" 2 . Theses changes caused the shift from "mass production" to "mass-customisation". In order to fulfil these new needs for agility, it becomes unavoidable for firms to develop an extremely flexible production structure able to: a) duly react to the market environment's turbulences; b) survive production system changes through the adoption of new technologies; c) adapt to the uncertainties of production systems in such environments.
Neither hierarchical or heterarchical systems are able to fulfil these requirements [3,4]. Hierarchical systems have a typically rigid structure which makes it very hard for them to react to turbulences in an agile way. Heterarchical systems are networks of elements with common aims in which each element shares with the others the same "horizontal" position of power and authority. Though heterarchical systems can easily adapt to environmental changes and turbulences, their control system cannot assure the high level of performance and the predictable organization behaviours needed for the industrial production of goods.

Theoretical Framework
The growing power of IT opened new possibilities in the worldwide arena and supplied management new and effective instruments for planning, budgeting, design and customer care. The central role of the customer thrived to the point that the supply chain has begun to be defined as the "demand" chain [5]. Literature on this topic shows several trends which manufacturing and supply chain systems have to adapt to [6,7]: a) the paradigm shift from mass production to semi-personalized production; b) the opening to collaboration with other agents in order to speed up production innovation and processes; c) the critical role of effective and efficient cooperation inside the network; d) understanding the problems connected to the implementation of a centralized control system between different entities with different information, experiences, activities, objectives and decisional authorities. 1 The hierarchical pattern on which mass production is founded presumes the steadiness of social, economic and technological factors. 2 In 1972 McLuhan & Nevitt [1] in "Take Today" suggested that electronic technologies would transform consumers into producers. Some years later, in 1980, the futurologist Alvin Toffler [2] in "The Third Wave" coined the term "prosumer", predicting the blurring of the distinction between producer and consumer due to the saturation of markets with standardized products which would have pushed towards the search for higher levels of differentiation and personalization of products.

Copyright © 2008 SciRes JSSM
These changes call for new organization structures. Traditional hierarchical systems show several inadequacies to work in these new business environments: a) they strongly limit the reconfiguration capacity, the reliability and the growth capacity of the organization [7]; b) their complexity grows together with the size of the organization [8]; c) communication among the elements of the system is strictly determined ex ante and vertically limited [9]; d) the structure's modules may not take initiatives, therefore reducing the system's readiness to react thus resulting not agile in turbulent environments environment [10]; e) the structure is expensive to build and to maintain. Heterachical systems do not have the limits of hierarchical systems, as they are able to obtain flexibility and adaptability to external stimuli. In heterachical systems every hierarchy is banned and power is given to the single "agents" 3 of the system. Agents interact with their environment and with other agents according to their own attributes and aims. Control is based on negotiation due the lack of hierarchy.
In the field of artificial intelligence, the term agent is used to define the intelligent elements of a system who observe and act in the environment as entities capable of awareness and purposive behaviors; such agents must have the following attributes [11,12]: -Autonomy -they act without the help or guide of any superior entity; -Social ability-they interact with other agents; -Reactivity-they perceive their environment and respond rapidly to changes; -Pro-activity-they are able to have initiative and specific behaviors for a specific scope.
For example, in a heterachical manufacturing system, the relation between the work station and supply orders is such that every supplier has direct contact with the work station in order to exploit all possible options to face unexpected fluctuations in supply and/or demand.
In spite of their agility, heterachical systems are not able to operate following predefined plans, hence their behavior is hardly predictable, increasing variability in systemic dynamics. Heterarchical structures work well in simple, non complex and homogeneous environments with abundance of resources [10], while in complex environments they can bring to instability because of their unpredictability; moreover, with scarcity of resources, they are not able to act efficiently due to the lack of planning.
It is therefore necessary to conceptualize and implement a system able to assure both performance and reactivity at the same time. The answer to this challenge could come from the theories on living organisms and social organizations, which, if applied to the business, present a representation of the firm as a living system. The holonic paradigm emerges in this research stream, amidst the holistic 4 approach and the vital systemic approach [13]. The holonic paradigm stems from the thoughts of Arthur Koestler [14] who underlined how complex systems can originate only if they are composed by stable and autonomous sub-systems, which are able to survive turbulences and, at the same time, can cooperate forming a more complex system. Koestler underscores that analyzing both the biological and the physical universe shows that, it is necessary to take into account the relations between the whole and the part of the entities we observe. To understand the abearance of the world, according to Koestler, is not enough to study atoms, molecules, cells individuals or systems as independent entities, but it is crucial to consider such unities as simultaneously part of a larger whole; in other words, we have to consider it as a holon. The term holon is a combination of the ancient Greek "ὅλος" with the meaning of "whole" and the suffix "ὄν" meaning "entity" or part; thus the whole is made of parts which unlike atoms are also entities. The holon is, indeed, a whole which includes, simultaneously, the elements or the subparts which form it and give it structural and functional meaning. Holons act as intelligent, autonomous and cooperative entities working together inside temporary hierarchies called "holarchies". A holarchy is a hierarchy of self-regulating holons working, in coordination with their environment, as autonomous wholes which are hierarchically superior to their own parts and, at the same time, are parts dependent by the control of superior levels. Figure 2 shows the general relationship between holon and holarchy.
Holons of the same level process elements and information coming from lower level holons and they transfer the results to higher level ones for further processing. Processes of holons belonging to level 'n' hence originate from Copyright © 2008 SciRes JSSM process of 'n-1' level subordinated holons and at the same time are the input for the processes of 'n+1' superior holons. [15,16]. The strength of the holonic approach resides in the concept of holarchy, which allows the development and implementation of extremely complex systems which are able to use resources efficiently, are resilient to disturbances and, at the same time, adaptable to changes of the environment. What makes the holonic system extremely effective in turbulent environments is that, inside a holarchy, holons are able to dynamically create and change hierarchies and also to participate to different hierarchies simultaneously. The holonic system can therefore be defined as a global and organized entity made of interrelations among highly self-regulating operative units which are able to cooperate with each other, keeping their autonomy, seeking shared results and common aims. It is possible to find the three pillars of holonic systems [17]: 1) the shared-value system in the organization allows the spontaneous and continuous interaction among groups of people who are far from each other and are not linked by legal or ownership ties, in order to take advantage of the economies of cooperation and of the increased stability of the system. Examples of shared value systems are some of the elements of lean production, that are often embedded in the company's vision, such as the principle of continuous improvement (kaizen); 2) the distributed network information system which is the neural sub-system [18] supporting real time supply of information between operating units which consents the pursuit of maximum income by better exploiting the coming business opportunities; 3) the autonomous distributed hierarchy which is based on the ability of each autonomous part to become leader according to requirements of specific situations caused by the turbulent changes in the environment. Every entity is able to directly interact with other entities without mediation. Due to this property in a holonic system every holon has potentially the same importance and the same responsibility; the involvement of a holon as operative unit is based on its knowledge and competencies and is not a consequence of predefined leadership.

The Holonic Production System
The Holonic Production System (HPS) can be a valid choice to overcome the problems of traditional production systems' architectures, thanks to its capability to adapt and react to changes in the business environment whilst being able to maintain systemic synergies and coordination. The HPS is made of holons seen as functional production units which are simultaneously autonomous and cooperative. These holons can be represented as networked agents which define different levels of a system [19].
Every element represented in Figure 4 is a holon (work cell, factory, firm, supply chain). At the supply chain level the interaction among firms, their suppliers and their clients takes place. It is possible to determine a subsystem for each firm in the supply chain level, this subsystem is an enterprise level holon. In the enterprise there is cooperation among factories and sales departments. Inside each factory there are several working cells which interact with each other; the working cell is the basic level of the holarchy described which is self-controlled by the interaction among men and machines [20].

Cases of Application of Theory and Further Possible Developments of Research
Although the holonic approach could represent a valid solution in order to pursue the necessary levels of agility of production systems, they have been scarcely implemented in practice and even less studied from a business studies perspective. Furthermore few studies of implementation of holonic-like systems can be found in the literature. Shen [21] noted that IBM has been one of the first firms to adopt a system based on intelligent agents to avoid bottlenecks and smooth production. Jennings & Bussman [22] developed a way to implement a standard modules system, where each module is flanked by an intelligent agent in order to compose a holon which becomes the building block of the system; this system has been tested by Daimler-Chrysler in order to evaluate its resilience of the system. The result obtained was of 99,7% of the theoretical optimum and the system has been adopted in the Factory of Stuttgart-Untertürkheim in Germany. The purpose of these notes is to show the benefits of further research on cases of implementation of HPS from a business organization studies perspective. Very little research on this topic has been done outside the field of business engineering and computer science; the study of this topic from a different perspective can shed the light on new aspects and new applications of the theory.
The HPS is surely not easy to implement in a real factory, nevertheless a step-by-step approach for the introduction of this system in those industries where the need for flexibility goes together with the scarcity of resources and margins, can become the way for the factory of the XXI century.


Hybrid Polling Method for Direct Link Communication for IEEE 802.11 Wireless LANs

The direct link communication between STAtions (STAs) is one of the techniques to improve the MAC performance of IEEE 802.11 infrastructure networks. For the efficient direct link communication, in the literature, the simultaneous polling method was proposed to allow the multiple direct data communication to be performed simultaneously. However, the efficiency of the simultaneous polling method is affected by the interference condition. To alleviate the problem of the lower polling efficiency with the larger interference range, the hybrid polling method is proposed for the direct link communication between STAs in IEEE 802.11 infrastructure networks. By the proposed polling method, we can integrate the sequential and simultaneous polling methods properly according to the interference condition. Numerical examples are also presented to show the medium access control (MAC) performance improvement by the proposed polling method.

PCF protocol
The AP transmits the polling frames to grant the transmission opportunities to the STAs. After the beacon frame, the AP waits for one Short InterFrame Space (SIFS) period, and then transmits to an STA a polling frame on which a data frame destined for the STA can be piggybacked. The STA should respond to the polling frame by transmitting to the AP its data frame on which the ACK frame corresponding to the data frame transmitted by the AP can be piggybacked. After the reception of the data frame transmitted by the STA, the AP transmits to another STA a polling frame on which a data frame and the ACK frame corresponding to the previous data frame transmitted by the STA can be piggybacked. The STA responds to the polling frame by transmitting its data frame on which the ACK frame can be piggybacked. The STAs can respond to the polling frames by transmitting the null frames if the STAs do not have the data frames to transmit. If the STAs fail to respond to the polling frames within one SIFS period following the transmissions of the  Figure 1: Modified CFP structure in [7].
AP, for the error recovery, the AP transmits a polling frame to another STA after one PCF InterFrame Space (PIFS) period from the end of the previous transmission. In this manner, the process of the AP's polling and the STAs' responding continues until the contention-free period (CFP) ends.

CFP structure
According to the superframe structure in [1], a CFP during which the PCF polls the STAs to grant the transmission opportunities alternates with a contention period (CP) during which the DCF controls the data transfer. S will represent the set of the STAs to which the transmission opportunities should be granted during a CFP. To support the simultaneous polling method in [7], the original IEEE 802.11 CFP structure was modified so that each CFP is divided into the multiple subperiods (SPs), each of which is composed of a polling interval (PI) and a direct communication polling interval (DCPI) as shown in Figure 1.
In the PI, similarly to the PCF protocol, the AP grants the transmission opportunities to the STAs by transmitting the polling frames to the STAs in an order. In the DCPI, the direct link communication is actually performed using the simultaneous polling method. If one or more direct data transmission opportunities are actually granted in the DCPI, only one transmission opportunity is granted to each transmitting STA of the direct link communication and two transmission opportunities are granted each to the other STAs in the PI of the next SP. This is for providing a fair allocation of the wireless medium to the STAs.

Connectivity and interference information
The simultaneous polling method is based on the connectivity and interference information among the STAs. We want to explain briefly the method for the APs collecting the connectivity and interference information among the STAs in the PI. Each STA i maintains the sets, S i and T i which are the sets of STAs of which the transmission signal can be heard by STA i, and can interfere with the data reception of STA i, respectively. STA i can obtain the MAC address of STA j ( / =i) from the polling frame transmitted by the AP before the transmission of STA j. For this purpose, the polling frames should be received by the STAs. When STA i hears the transmission signal of other STA j not in S i , STA i adds STA j to S i . When STA i has not heard the transmission signal of other STA j in S i during recent three PIs, STA i deletes STA j from S i . In this manner, each STA can maintain the set, S i . STA i can also maintain the set, T i as follows. When STA i finds the reception power level of the transmission signal of Woo-Yong Choi 3 other STA j not in T i to be above that of the background noise, STA i adds STA j to T i . When STA i has not found the power level of the transmission signal of other STA j in T i to be above that of the background noise during recent three PIs, STA i deletes STA j from T i . Actually, each STA i can piggyback the MAC addresses of the STAs that are deleted from or added to S i and T i on the response null or data frames transmitted to the AP. Considering the case when transmission errors occur, we modified the method in [7] for the APs collecting the connectivity and interference information to wait for three PIs before deleting STA j from S i or T i .
With the asymmetric connectivity and interference condition, the AP needs two PIs to collect the connectivity and interference information among the STAs when no transmission error occurs. In order for STA i to obtain the connectivity and interference information between STA i and STA j ( / =i), the following two events should sequentially occur in a PI: (i) the polling frame destined for STA j is successfully received by STA i and STA j; (ii) the response frame transmitted by STA j is successfully received by STA i when STA i is within the transmission range of STA j. STA i can detect the interference by the reception power level of the response frame transmitted by STA j when STA i is within the interference range of STA j.
Denoting the probabilities that the two events occur in a PI by p 1 and p 2 , we can compute the probability that STA i can successfully obtain the connectivity and interference information between STA i and STA j within three PIs as P = 1−(1 − p 1 p 2 ) 3 . When the failure probabilities of the two events are less than or equal to 0.05, that is, p 1 and p 2 ≥ 0.95, P > 0.999, therefore, we can infer that it is quite reasonable to wait for three PIs before deleting STA j from S i or T i . In the PI, after the four-step process of establishing the direct link connection in [5], each STA can request at most one direct data transmission opportunity by piggybacking the MAC address of the recipient of the direct data transmission on the response null or data frames transmitted to the AP. Based on the connectivity information, the AP can determine whether the direct link connection can be established to serve the direct link communication. After the successful four-step connection establishment process, each STA can optionally transmit its data frame directly to the recipient by writing the MAC address of the recipient in the recipient address (RA) field of the MAC header of the data frame transmitted when it is granted the transmission opportunity in the PI. The constants, C i, j and I i, j for i and j ∈ S, and i / = j and d(i) for i ∈ S, which are collected in the PI to specify the connectivity and interference information, and the information of the STAs' requests for the direct link communication, respectively, are defined as follows: (iii) d(i): the MAC address of the recipient of the direct data transmission that STA i requested on a packet basis in the recent PI. If STA i did not request the direct data transmission, d(i) = 0.

Simultaneous polling method
The simultaneous polling method is the multipolling method that allows the AP to poll a group of The efficiency (or the number of simultaneous direct transmissions) of the simultaneous polling method depends on the interference range of STAs. In cases where the simultaneous polling method is not effective due to the large interference range, the simultaneous polling method needs to be enhanced to alleviate the problem of the lower polling efficiency with the larger interference range.

HYBRID POLLING METHOD
The real-time services such as VoIP do not usually require the ACK frame transmission. We assume that the ACK frame transmission can be omitted. When an STA, having one or more established direct link connections, malfunctions, is just switched off or moves out of the transmission range, without the ACK transmission, the AP can detect that the direct link connections are broken using the connectivity information that will be collected in the next PIs. With the proposed polling method that is used to grant the requested direct transmission opportunities to the STAs in the DCPI, the AP transmits a multipolling frame to the STAs in the sequence G S = {STA U 1 , STA U 2 , . . . , STA U M } and the group G P = {STA W 1 , STA W 2 , . . . , STA W N }. The STAs in the sequence G S transmit their frames sequentially after the multipolling frame is received. An SIFS period after receiving the multipolling frame, STA U 1 first attempts to transmit its frame. An SIFS period after sensing the end of the transmission of STA U 1 , STA U 2 attempts to transmit its frame. STA U 3 attempts to transmit its frame an SIFS period after sensing the end of the transmission of STA U 2 . In this manner, the STAs transmit their frames sequentially. An SIFS period after sensing the end of the transmission of STA U M , the STAs in the group G P transmit their frames  (1), the following connectivity condition should be satisfied for the proposed polling method: If an STA in G S fails to respond to the multipolling frame or the transmission of the previous STA in the sequence within an SIFS period following the transmission of the AP or the previous STA, for the error recovery the AP will transmit the multipolling frame to repoll the next STAs in the sequence G S and the group G P after a PIFS period, which is an SIFS period plus a slot time, from the end of the previous transmission. The format of the multipolling frame is shown in Figure 2.
In Figure 2, U 1 , U 2 , . . . , and U M indicate the MAC addresses of the STAs in the sequence G S , W 1 , W 2 , . . . , and W N the MAC addresses of the STAs in the group G P , and M and N are the numbers of the STAs in the sequence G S and the group G P , respectively. The other fields are from [1]. We can omit G S or G P . When G S (or G P ) is omitted in the multipolling frame, the simultaneous (or sequential) polling method is only specified.
When all direct data transmission opportunities are granted, the AP initiates the next PI by transmitting a polling frame to an STA an SIFS period after the response transmissions from the STAs are completed or can initiate the next PI after the wireless medium is determined to be idle during a PIFS period.

SCHEDULING ALGORITHMS
In this section, we propose two scheduling algorithms applicable to the hybrid polling method: the packet-level and the connection-level scheduling algorithms. By performing the packet-level scheduling algorithm at the beginning of DCPIs, the AP can schedule efficiently the direct data transmissions requested on a packet basis. The connectionlevel scheduling algorithm derives the polling sequence for granting the transmission opportunities to the transmitting STAs of all existing established direct link connections. When polling the STAs in DCPIs, by a simple method, the AP modifies the polling sequence derived by the connectionlevel scheduling algorithm considering the information of the STAs' requests for the direct link communication. The connection-level scheduling algorithm is suitable for the case when the AP cannot perform the packet-level scheduling algorithm quickly enough to reflect exactly the STAs' new requests for the direct link communication in the next DCPI. However, in the cases where the connectivity and interference information and the information of the STAs' requests for the direct link communication do not change for a period of time during which the AP can derive the polling sequence by the packet-level scheduling algorithm or a small number of STAs actually request the direct link communication, the packet-level scheduling algorithm should be applied for the efficient use of the wireless bandwidth. Note that when no STA requests the direct link communication, the next DCPI will be skipped.

Packet-level scheduling algorithm
In the DCPI, the AP needs to schedule efficiently the requested direct data transmissions based on the connectivity and interference information among the STAs and the information of the STAs' requests for the direct link communication. Let V be the set of STAs that requested the direct data transmissions, which are determined to be feasible using the connectivity information, in the recent PI. Then V can be obtained as follows: We propose a two-phase scheduling algorithm for granting the direct transmission opportunities to the STAs in V using the proposed polling method.
In the first phase of the algorithm, we handle the problem of grouping the STAs in V with as few groups as possible in such a way that no two STAs, i and j with I i,d( j) = 1 or I j,d(i) = 1, are in the same group. Note that the connectivity and interference conditions as shown in (1) are satisfied for each group. Therefore, the AP can grant the simultaneous direct transmission opportunities to the STAs in each group using the simultaneous polling method. This grouping problem can be formulated as graph coloring problem (GCP), where the STAs in V are vertices and two STAs, i and j in V , are connected only when I i,d( j) = 1 or I j,d(i) = 1. We can use the simple heuristic for GCP, which is based on the degree-descending order of the vertices [9, page 14]. The set of the groups obtained by the heuristic is denoted by [9, page 14]. We need L polling frame transmissions to poll the STAs in the groups in G using the simultaneous polling method. The first phase of the algorithm was considered in the simultaneous polling method in [7].
In the second phase of the algorithm, we try to further reduce the number of polling frame transmissions by applying the sequential polling method to the groups in G.
Woo-Yong Choi 5 The AP can poll the STAs in the groups in the sequence for i / = j by transmitting a multipolling frame, the format of which is as shown in Figure 2, to the STAs when only one STA exists in H(i) for i = 1, 2, . . . , K − 1, and the following connectivity condition is satisfied: where C H(i),H(i+1) = 1 indicates that the STAs in H(i + 1) can hear the transmission of the STA in H(i). We will call such a polling sequence satisfying the condition of (4) sequentially connected. For convenience of explanation, we will also call the sequence H having only one group sequentially connected. When some of the groups in G have only one STA, that is, the simultaneous polling method cannot be actually applied to some of the groups, we can further reduce the number of polling frame transmissions by finding the sequentially connected polling sequences and applying the proposed polling method to the sequentially connected polling sequences. The problem of finding the optimal polling sequence of the groups in G that minimizes the multipolling frame transmissions can be formulated as the asymmetric traveling salesman problem (TSP), where the groups in G are L cities, and the distance, Let us denote the sequence as a solution of the TSP by H * = {H * (1), H * (2), . . . , H * (L)}, and the corresponding total distance by Z * . If Z * = 0, that is, H * is sequentially connected, only one multipolling frame transmission is sufficient to grant the direct transmission opportunities to the STAs in the groups in G. If Z * = 1, we can cyclically reorder the groups in H * to obtain the sequentially connected polling sequence, H 1 , and only one multipolling frame transmission is sufficient to poll the STAs in the groups in G. If Z * = 2, we can cyclically reorder the groups in H * to obtain two sequentially connected polling sequences, H 1  To solve the asymmetric TSP, we can use the following dynamic search algorithm. = 1 μs)).

Algorithm 1 (DYNAMIC SEARCH (Time Limit
Step 1. Set Bounding Cost = R (the number of the groups having two or more STAs in G).
Step 2. Start to search the enumeration tree with Bounding Cost.
Step 3. If a solution with the cost less than or equal to Bounding Cost is found using the branch and bound technique based on the depth-first search method within Time Limit, the solution is the result of the algorithm and the algorithm is terminated. Otherwise, update Bounding Cost : Bounding Cost ← Bounding Cost + 1, and go to Step 2.
When R is the number of the groups having two or more STAs in G, at least R multipolling frame transmissions are needed to poll the STAs in the groups in G. The preceding algorithm first tries to obtain the solution with Z * = R. If the algorithm does not succeed to get the solution within time of Time Limit, the algorithm relaxes the constraint for the cost of the solution by increasing Bounding Cost by 1 and tries to get the solution with Z * = R + 1. If the algorithm fails again, the algorithm again increases Bounding Cost by 1 and tries to get the solution with Z * = R + 2. In this manner, the algorithm continues until the solution with Z * = Bounding Cost is obtained. By the branch and bound techniques, if a part of tour has a cost higher than or equal to the current optimal cost or higher than Bounding Cost, all tours including this part of tour are skipped.

Connection-level scheduling algorithm
Let Y be the set of existing simplex direct link connections. A duplex connection can be realized by two simplex connections. We propose a two-phase scheduling algorithm for granting the direct transmission opportunities to the transmitting STAs of the direct link connections in Y . We will denote the transmitting and receiving STAs of direct link connection, q in Y by T(q) and R(q), respectively.
In the first phase of the algorithm, we handle the problem of grouping the connections in Y with as few groups as possible in such a way that no two connections, q1 and q2 with I T(q1),R(q2) = 1 or I T(q2),R(q1) = 1, are in the same group. This grouping problem can be also formulated as GCP, where the connections in Y are vertices and two connections, q1 and q2 in Y , are connected only when I T(q1),R(q2) = 1 or I T(q2),R(q1) = 1. We can use the simple heuristic for GCP, which is based on the degree-descending order of the vertices [9, page 14]. The simultaneous polling method can be actually applied to the groups with two or more connections [9, page 14]. We will call such groups with two or more connections and the groups with only one connection the simultaneous polling groups and the nonsimultaneous polling groups, respectively.
Generally, a transmitting STA can have two or more established direct link connections. However, we want to grant at most one direct transmission opportunity to each STA. For this purpose, when a nonsimultaneous polling group obtained by the heuristic consists of a connection with a transmitting STA, we need to remove the other connections with the transmitting STA from other groups before we go to the second phase of the algorithm. Generally, 6 EURASIP Journal on Wireless Communications and Networking we can say that the connections with a transmitting STA cannot be in the same simultaneous polling group due to the interference. Actually, we want to avoid the case that two or more connections with a transmitting STA are separately in the nonsimultaneous polling groups, and the case that two or more connections with a transmitting STA are scattered in both the simultaneous and nonsimultaneous polling groups. Note that we allow the case that two or more connections with a transmitting STA are individually in the different simultaneous polling groups. When two or more connections with a transmitting STA are individually in the different simultaneous polling groups, the STA should choose only one connection to transmit its direct data frame when polled by the AP. The set of the groups obtained by the first phase of the algorithm is denoted by G C = {G C (1), G C (2), . . . , G C (L C )} for L C ≥ 1. We need L C polling frame transmissions to poll the transmitting STAs of the connections in the groups in G C using the simultaneous polling method.
In the second phase of the algorithm, we try to further reduce the number of polling frame transmissions by applying the sequential polling method to the groups in G C . The AP can poll the transmitting STAs of the connections in the groups in the sequence by transmitting a multipolling frame, the format of which is as shown in Figure 2, to the STAs when only one connection exists in H C (i) for i = 1, 2, . . . , K C − 1, and the following connectivity condition is satisfied: C T(HC(i)),T(HC(i+1)) = 1 for i = 1, 2, . . . , K C − 1, (6) where C T(HC(i)),T(HC(i+1)) = 1 indicates that the transmitting STAs of the connections in H C (i + 1) can hear the transmission of the transmitting STA of the connection in H C (i). We will call such a polling sequence satisfying the condition of (6) sequentially connected.
When some of the groups in G C have only one connection, that is, the simultaneous polling method cannot be actually applied to some of the groups, we can further reduce the number of polling frame transmissions by finding the sequentially connected polling sequences and applying the proposed polling method to the sequentially connected polling sequences. The problem of finding the optimal polling sequence of the groups in G C that minimizes the multipolling frame transmissions can be also formulated as the asymmetric TSP, where the groups in G C are L cities, and the distance, D GC(i),GC( j) from G C (i) to G C (i), is binary valued: Let us denote the sequence as a solution of the TSP by H C * = {H C * (1), H C * (2), . . . , H C * (L C )}, and the corresponding total distance by Z C * . If Z C * = 0, that is, H C * is sequentially connected, only one multipolling frame transmission is sufficient to grant the direct transmission opportunities to the transmitting STAs of the connections in the groups in G C . If Z C * > 0, we can cyclically reorder H C * to obtain Z C * sequentially connected polling sequences, H C 1 , H C 2 , . . . , and H C Z * , and Z C * multipolling frame transmissions are sufficient to grant the direct transmission opportunities to the transmitting STAs of the connections in the groups in G C . To solve the asymmetric TSP, we can employ a dynamic search algorithm similar to the one of the packet-level scheduling algorithm with Time Limit of 10 seconds.
When a group in H C * consists of a single connection, the transmitting STA of the connection can transmit its direct data frame to any receiving STA of the established direct link connections in its transmission range when polled by the AP. When the transmitting STA of the connection has no direct data frame to transmit, the STA should use the granted transmission opportunity to transmit its null or data frame to the AP when polled by the AP. The AP can optionally modify the derived polling sequence to insert the AP's polling frame transmissions before the transmissions of the nonsimultaneous polling groups when the AP has the data frames, which are actually piggybacked on the polling frames, destined for the nonsimultaneous polling groups. When no direct link communication through the connections in a simultaneous polling group in H C * was requested, the AP will modify the derived polling sequence to remove the group from the polling sequence that is actually delivered to the STAs. This is for avoiding wasting the wireless bandwidth. When all connections with a transmitting STA are separately in the different simultaneous polling groups, the STA can choose only one connection to transmit its direct data frame when polled by the AP. Note that the first phase of the algorithm avoided the case that two or more connections with a transmitting STA are separately in the nonsimultaneous polling groups, and the case that two or more connections with a transmitting STA are scattered in both the simultaneous and nonsimultaneous polling groups.

SIMULATION RESULTS
To show the MAC performance improvement by the proposed hybrid polling method, for each number of STAs, |S| = 20, 30, and 40, we generated ten IEEE 802.11a wireless LANs, where the APs are located at the centers of the circular service areas, and twenty, thirty, or forty STAs are randomly located in the service areas, including the one consisting of one AP and thirty STAs in Figure 3. Each wireless LAN serves one or more simultaneous full-duplex VoIP traffic streams between STA i and STA |S| − i + 1. B will denote the number of simultaneous full-duplex VoIP traffic streams between two STAs of each pair. The STAs perform a good uplink power control in PIs so that the null or data frames transmitted by each STA can be received by the STAs including the AP in the circular transmission range with the radius r of the distance between the STA and the AP, and the STAs out of the transmission range cannot hear the transmission signal of the STA.
In Figure 3, the eleven STAs indicated by the shaded circles can transmit the VoIP traffic streams directly to their  From the uplink power control, we can obtain the connectivity information among the STAs. The transmission and interference ranges are mainly determined by transmission power, radio propagation properties, and signal-to-noise ratio (SNR) threshold. In practice, the interference range is larger than the transmission range. We consider five cases of the interference range with the radius R in each wireless LAN [10]. The connectivity information remains the same in all five cases. In the first case, R = r, that is, the interference ranges are set to the same as the transmission ranges. R is set to 1.3 r, 1.5 r, and 1.8 r in the second, third, and fourth cases, respectively. According to [10], the corresponding SNR threshold values of the second, third, and fourth cases are approximately 2.9, 5.1, and 10.5, respectively. Finally, the interference ranges are set to be large enough for the data transmission of each STA to interfere with the data receptions of all other STAs in the last case.
For convenience of simulation analysis, we assume that the connectivity and interference information do not change over time. When the connectivity and interference information change, only the change of the connectivity and interference information is actually delivered to the AP. For example, if five MAC addresses per second, which are actually piggybacked on the response null or data frames transmitted to the AP, need to be delivered to report the change of the connectivity and interference information among the STAs, only the data rate of 5 * 6 bytes/second = 240 bps is required for this overhead.
As the result of the first phase of the packet-level and the connection-level scheduling algorithms applied to the five cases when the eleven STAs, 1, 4, 7, 8, 14, 15, 16, 23, 25, 27, and 30 request the direct data transmission opportunity on a packet basis, we obtained the following groups, each of which consists of the STAs that can be simultaneously polled using the simultaneous polling method:   For convenience of simulation analysis, we assume that the CP does not exist, and only the CFP exists. The burst and idle periods of each VoIP traffic stream are 1.5 seconds and 1 second, respectively. The length of the user payload of each VoIP data frame is 88 bits [11]. When the improved multiband excitation (IMBE) speech coder is used, the total number of VoIP data frames generated in a burst period by each VoIP traffic stream is 4.8 Kbps * 1.5 seconds/88 bits = 82, where 4.8 Kbps is the speech coding rate of the IMBE speech coder [11]. A VoIP data frame consists of the user datagram protocol (UDP), internet protocol (IP) and MAC layer headers, and the user payload. The lengths of the UDP, IP, and MAC layer headers are 16 bits, 224 bits, and 224 bits, respectively [1,11]. One SIFS period of 16 microseconds, one PIFS period of 25 microseconds, and the physical layer header transmission time of 24 microseconds are used [1,2]. We assume that all data, polling and multipolling frames are transmitted with the peak rate, 54 Mbps. It is assumed that the ACK frame transmission for the VoIP traffic streams can be omitted. We also assume that a PCF polling frame and Woo-Yong Choi   a polling frame transmitted in PIs can optionally have two recipient MAC addresses, one indicating the polled STA and one indicating the recipient of the data frame piggybacked on the polling frame. When the polled STA and the recipient of the piggybacked data frame are the same, the polling frame will have only one recipient MAC address.
The maximum delay bound for each combination of wireless LANs, interference conditions, and traffic loads was obtained by computer simulation during about 3 * 10 7 time slots using the specialized simulator developed in C code by the author. One slot time is 9 microseconds in IEEE 802.11a wireless LANs. In Figures 4,5,6,7,8,9,10,11, and 12, we present the simulation results of the maximum delay bounds of IEEE 802.11a wireless LAN with the conventional PCF polling method with the direct link communication technique in [5], the simultaneous polling method in [7], and the hybrid polling method in Section 3. The results of the mean delay bounds, which are encountered by at least 99% of the VoIP data frames transmitted in wireless LAN, were obtained for the five interference conditions, the three traffic loads and the three numbers of STAs in a wireless LAN. It is  assumed that the VoIP data or polling frames are transmitted erroneously with probability of 0.001.
As can be seen in Figures 4 to 12, the increase of the interference range negatively influences the performances of the simultaneous polling method and the hybrid polling method. Note that the interference range does not influence the performance of the PCF polling method. Comparing the results of the simultaneous polling method and the proposed polling method, we can see that the hybrid polling method copes with the increase of the interference range better than the simultaneous polling method. The performance of the simultaneous polling method decreases sharply after the interference condition of R = r, and becomes the same as that of the PCF polling method under the severe interference condition of R = ∞. However, with the hybrid polling method, the decrease in the MAC performance is relatively small even in the interference conditions of R = 1.8 r and ∞. Compared with the simultaneous polling method, the hybrid polling method decreases the mean delay bound by about 7.6%, 11.0%, 18.5%, 27.8%, and 40.5% under the interference conditions of R = r, 1.4 r, 1.5 r, 1.8 r, and ∞, respectively. Compared with the PCF polling method, the hybrid polling method decreases the mean delay bound by about 58.8%, 45.1%, 39.1%, 38.0%, and 38.9% under the interference conditions of R = r, 1.4 r, 1.5 r, 1.8 r, and ∞, respectively. From the simulation results, we can see that the hybrid polling method outperforms both the PCF protocol and the simultaneous polling method in maximum delay especially under the severe interference condition.
For a bandwidth-efficient direct link communication, we need to reduce the number of polling frame transmissions in DCPIs because the transmissions of the polling frames on which the data frames are not usually piggybacked for the direct link communication are the scheduling overhead in the simultaneous and hybrid polling methods. While with the simultaneous polling method the AP should transmit the separate polling frames to poll the STAs for the direct link communication under the severe interference condition, with the hybrid polling method, the AP can reduce significantly the number of polling frame transmissions using the connectivity among the STAs. The hybrid polling method can improve the MAC performance by reducing the scheduling overhead.

CONCLUSIONS
In this paper, we proposed the hybrid polling method for supporting direct link communication between STAs in IEEE 802.11 wireless LANs. Compared with the simultaneous polling method proposed in the literature, the proposed polling method can improve the MAC performance by reducing the number of polling frame transmissions using the connectivity among the STAs. Simulation results show that the proposed polling method is useful especially when the interference range is large.