1. Field of the Invention
This invention relates generally to an apparatus and method for providing variable bandwidth in wireless air-link communication and more specifically, to an apparatus and method for allowing a user of a mobile communication radio, e.g. a cellular telephone and portable computer, to be allocated wireless variable bandwidth on demand by aggregating available air-link communication channels.
2. Description of the Background Art
Data or information transmissions commonly occur between desk top or personal computers communicating from different locations, between computers and facsimiles, and between telephones and computers. In any communication, the transmitting device is identified as the "originator" or "originating address," while the receiving device constitutes the "target address." The originating device and target device typically change roles several times in any ongoing communication, but at any given time, one device is the originator and the other is the target.
A simple computer network includes an originator device, at least one information transfer network, a target device, and the cable connections joining the originator, information transfer network, and target. The originating and target devices typically include computers which communicate through modem, servers or local area networks utilizing either a server, modem or both in direct link transmissions. The communicating devices used today also include mobile cellular telephones, portable computers, portable facsimiles, and combinations thereof which communicate over wireless air-link channels. Direct link communicating devices generally transfer information through direct link, i.e. wire or cable connections which typically comprise either commercial telephone lines, copper cables, fiber optic cables, leased lines, or private lines. In a direct link transmission, the information transfer network receives the messages or data from the originator and delivers or routes the communication to the target address. Due to the stable, error free nature of these links, either continuous high speed or lower speed, packetized transfers are allowed. In wireless transmission, messages are broken down into smaller chunks, the size of which is dependent on the intervening network, transmission speed and error correction techniques, and transmitted across an air-link channel of fixed speed to a transceiving station. These chunks of user data are then either encapsulated into packets and sent through a packet network or just sent sequentially through non-packet networks to their target device. More than one information network of packet and non-packet systems, commonly referred to as clouds, may be involved in any communication transmission, depending on the management of the intervening networks, the size of the message and the distance between the originator and ultimate target.
Information transfer networks generally include either a non-packet system, such as public switch telephone network (PSTN) or packet networks. The PSTN, or non-packet network, is the type of network used by telephone carrier companies. PSTNs generally include a plurality of circuit switches which route end-user messages through the phone lines when preselected switches are activated by the dialing of a number. End-user messages in a PSTN are usually segmented and sent in a predetermined sequence for a predetermined length of time, as logged on the communications software and modems employed by the network to their target address or modem. The PSTN periodically stops to re-sync itself and check for errors. Telephone carriers charge the computer user or users for the entire time a PSTN connection is made between communicating devices, regardless of whether information is being conveyed. It is directly analogous to being charged for a long distance phone call. Computers generally communicate in PSTN via dialed-digits and modems, which provide direct links between the computers through the telephone lines. The modem, like a phone, dials the desired phone address of the target computer modem, activating corresponding switches in the PSTN to access the target address. Accordingly, any time a communication link is made between computer modems, the users are charged during the entire time the modems have a communication link.
Packet networks offer an alternative to PSTN communication. Packet networks provide public and private communication network clouds which are command base services that utilize a mesh of packet routers for transmitting packets of data information. A mesh of packet routers usually comprises a typical packet network, whereby the network delivers the packet through a select packet router route. In contrast with PSTN carrier systems, packet communication network servers use packet routers to route and deliver end-user message chunks in packets and customers are generally charged by the number of packets or the number of bits of information per packet being transmitted. A packet router is therefore nothing more than a communication transmission carrier which temporarily stores and forwards a packet of information as it is routed to its target address, or to another packet router for delivering the communication. The message chunks of user data are encapsulated into packets with address headers, error correction bits, synchronization bits, and the like. The packets are routed through packet router networks to their target address. The number of routes used for delivering a message or data string is based on the management of the network cloud, the capacity of the network, and the size of the transmission load. Accordingly, some messages may only go through one router before delivery to the target, while other messages may go through a string of routers before reaching the target destination.
Communication between packet networks or a packet network and target is accomplished through modems and software, albeit different from those used in PSTN. Packet networks use formal address, e.g. "User ID, a computer name, a company name, a network name," which may be in plain text, numeric digit strings, or a mixture thereof, based on the type of networks traversed by the addressed messages.
Local area networks (LAN) are reasonably small and local groups of computers connected by one of a small number of standard methods, such as Ethernet. For instance, the computers may share the network as peers, or a shared resource called a server may be employed to support the computers in the LAN so that they may communicate with other networks such as in Internet. In essence, the server provides a gateway to other networks. The server may also be a print server acting as printer queues or a file server for accessing file libraries. Communication servers may have routing functions built in or may connect to external routing machines when attaching to a network. These external routing machines may be packet routers in the case of a packet data network, or a pool of modems that the end-user computers access and share in the LAN. In the former, the server provides a link between the packet routers and target devices whereby the LAN directly links the communication from the server to the target address based on the user identification code or address of the target terminal. LAN network services either lease telephone lines from telephone line carriers or provide private lines for transmitting packets of communication data.
Typically, computers utilize servers for communicating with packet routers. To initiate a data transmission, the computer, through its user ID, sends a command to the LAN to transmit a communication to a desired target address. The LAN activates its server and then sends a command and data through the server, which links with the desired information transfer network, such as a packet router network. Not all computer terminals however, are necessarily linked through a local area network, that is, they may also communicate directly with a server in preparing data transfers through the packet router system. A packet transfer network accepts the data transmission into a selected packet router which temporarily stores the information in packets and delivers it to the next router, if required, until the data transfer ultimately reaches the servers of the target computer or computers. The target server locates the target address and prepares the target terminal or the target LAN for receiving and routing the data transfer to the target terminal.
The size of the data information and communication channels dictates the speed of transmission. For instance, small messages in the low kilobyte range may only take minutes to transmit, while a megabyte message, such as a large spreadsheet or video, could take hours, depending on the computers and information transfer network being employed. Consequently, in a typical low speed PSTN system which charges customers by the duration of time a communication link is sustained, large messages are relatively expensive to transmit. Although communication networks utilizing packet routers are less expensive because they charge by the packet rather than strictly for on-line time, these systems may also become expensive when transmitting large messages at fixed speeds.
Devices which are directly linked and which communicate through packet routers and servers, and in some cases through PSTN switched circuits, are able to use channelized transmission equipment to vary the bandwidth of transmission in wire or direct links to increase the speed of transmissions. Channelized equipment increases the size of the communication bandwidth so that large messages may be more conveniently and quickly transmitted between locations. Conventional channelized equipment searches the transmission lines for available channels and aggregates these channels together so that a larger overall bandwidth is obtained. Before a transmission, the originating computer sends a command through the packet router, demanding an aggregation of channels for increased bandwidth. The channelized equipment locates and aggregates the available channels by dedicating the requested bandwidth from the total bandwidth available on that particular transmission path.
The problem, however, is that the aggregation of communication channels is not available for wireless air-link protocols which transmit information across bandwidth channels in the airways. That is, conventional wireless communication systems are not able to aggregate air-link available channels to increase the overall bandwidth of air-link communication channels like computer systems communicating directly through cable or telephone lines. Instead, wireless communication is limited to transmission at fixed speeds, i.e. through a single channel, because variable bandwidth is not available. Although a plurality of channels exists at any given time for transferring communication data across wireless links, each of these channels has a fixed bandwidth. But, even though channel aggregation has been done for wired links, the same is not true for wireless communication. Remote subscriber communication devices today are not able to allocate variable air-link bandwidth on demand to increase the overall bandwidth of available air-link channels for wireless or air-link transmissions. While the computer sending information across a direct cable link can command larger bandwidth and vary that bandwidth according to its demand, remote devices such as mobile cellular phones, portable computers, or portable facsimile machines are limited to single channel transmission. That is, remote communication devices initially transmit data across a wireless highway in a fixed bandwidth channel to a transceiving station, and are unable to demand increased bandwidth or the aggregation of available channels to increase the overall bandwidth or speed of wireless data transmissions. Thus, the ability to aggregate direct link channels is of no benefit in wireless communication whereby the transmission of messages is slowed in the air-links because of the inability to increase bandwidth.
Consequently, the existing wireless air-link protocols only allow data transmission at fixed speeds, typically one speed for any given network. In some cases, this is due to the frequency of a channel and the guardband separations of existing radio channels, but in most cases, it is due to the inability to easily request more bandwidth capacity with additional channels, and to aggregate the existing channels into a higher bandwidth channel. As a result, the transfer of messages having a relatively large amount of data is limited to a single channel of fixed bandwidth so that it takes much longer to transmit over air-links than through conventional systems communicating across wired links. Thus, the relevant link requiring increased bandwidth and channel aggregation is the wireless air-link between remote or mobile communication devices and transceiver stations. This is because once a communication reaches a local receiving point, it may be transferred across aggregated channels in cables such as telephone lines. Accordingly, there exists a need for an apparatus or method that aggregates wireless air-link channels for increasing the overall bandwidth of wireless communication transmissions so that the full capacity of end-user communication systems may be capitalized.
Several devices are contemplated in the background art which assign channels, provide alternate routing of channels, use guardbands to carry data, optimize channel use in a given location, utilize channel hopping between quiet spots in channels, and assign channels for radio communication transmission. However, none of these devices solve or address the above-noted problems or provide systems which search, locate and aggregate available channels in wireless air-link communication zones for increasing the speed and efficiency in the transmission of information across wireless or radio channels. For instance, Ash et al., U.S. Pat. No. 5,130,982, teaches a communication network for allocating bandwidth comprising a plurality of interconnected nodes having a subdivided bandwidth for sharing the network bandwidth among the network nodes. The network uses a shared pool of bandwidth commonly connected to the nodes which establishes direct wired links or paths between the nodes for handling information of transmission traffic. Ash et al. establishes direct links between network nodes but does not allocate and aggregate available radio channels for varying or increasing bandwidths across wireless links.
Hasegawa, et al U.S. Pat. No. 5,065,399 discloses a method for restoring a telecommunication path between network nodes after an interrupting network direct link failure. Hasegawa teaches an automatic network restoration method which is adapted to restore direct link communication between nodes when the default communication link terminates because of a failed link. Hasegawa searches for the link with the highest spare bandwidth based on the bandwidth lost in the failed communication link and chooses the direct links between nodes having the highest bandwidth capacity for replacing the path lost. Hasegawa, however, does not focus on the end-user and does not search for and aggregate available air-link channels on demand to increase or vary bandwidth in wireless communication.
In U.S. Pat. No. 4,280,630, Wang discloses a method for assigning individual channels based on last usage and last quality. Wang teaches a base station and a radio communication system comprising a channel allocator that allocates communication channels from a preferred channel list. The channels are allocated in accordance with a mean margin value with respect to a predetermined threshold channel quality. Wang does not teach a dynamic bandwidth air-link allocation system for improving the efficiency of wireless information transfer from transmission. Rather, Wang allocates single channels for direct link communication.
Ito et al., U.S. Pat. No. 5,210,752, discloses a radio telecommunication system for using fixed bandwidth channels that would normally be voice channels to carry network control signals in a way that insures rapid call setup and start timing in congested areas. Ito et al. teaches a radio telecommunication system for determining whether a central radio frequency can be used by locating free time slots in a channel having a plurality of speech radio slots. Ito et al. tries to respond to an increase in central traffic without preparing a large number of controlled radio frequencies. Ito et al. determines which radio frequency can be used, determines if each time slot on the plurality of speech radios is free and selects a radio channel based on the free time slots.
George, U.S. Pat. No. 5,214,789, teaches a method of optimizing radio channel utilization when the location of a mobile radio is known. A channel is assigned to a mobile radio based on the location of the mobile radio to optimize communication channel allocation in given zones. George does not aggregate channels on demand for maximizing transmission efficiency with increased bandwidth allocation. Rather, George concentrates on the location of mobile users to optimize the allocation of channels in particular zones.
Finally, Bronder, et al. U.S. Pat. No. 5,005,169, teaches a frequency division multiplier guardband communication system that uses low powered signals in existing guardbands to carry data. The signals pretend to be noise by staying below a specified power level so that interference with the recovery of the main frequency division multiplier does not occur.
The above-noted references do not provide an apparatus or method for wireless variable bandwidth communication across air-link channels at the demand of the end-users. Variable bandwidth for wireless communication in the radio air-links is important for increasing the efficiency and speed of communication data transmissions which conventionally has been limited to fixed speeds because transmission has only been possible across a single air-link channel. Consequently, there exists a need for a device and method for varying the bandwidth of air-link channels used in wireless communication for improving the efficiency and speed of information transmission. The present invention provides such a system and method which searches, locates, and aggregates available air-link channels for increasing the overall bandwidth of the wireless communication link, which in turn increases the speed and efficiency of transmission.