Growth of cellular communication and wireless Internet continues to provoke further studies that focus at evaluating the performance of wireless system under various limitations, developing new schemes and technologies to overcome limitations and meeting the growing demand of communication capacity and quality. The current Special Issue of the Journal of Communication presents research works on the channel characterizations, modulations schemes, and equalization techniques for wireless communication systems.      The Special Issue presents selected papers from the IEEE International Conference on Computer and Information Technology held on December 25-27, 2008. From more than 100 papers presented at the conference in the broad topic of communication, only 11 best papers were considered by the Editors, and their authors were then invited to enhance their papers significantly and submit the same to the Special Issue. Through an extensive peer review process, only 6 papers from among these enhanced papers were finally selected by the Guest Editors for publication in this Special Issue. These authors represent academic and/or research institutions from Australia, Bangladesh, Italy, Japan, and Malaysia.      In the first paper, M.Z. Alam, C.S. Islam, and M.A. Sobhan investigate the bit error performance of a quadrature amplitude modulation based wireless communication system using log-likelihood ratio. The theoretical and simulation results compare different diversity techniques for Rayleigh fading channel and recommend the maximal ratio combiner to be the most suitable scheme for wireless communication.      The second paper is contributed by M.R.H. Mandal and S.P. Majumder, which evaluates the bit error performance of an orthogonal frequency division multiplexed wireless communication system including the impact of time selective fading, timing jitter and additive white Gaussian noise. Different modulation schemes, namely differential phase shift keying, quaternary phase shift keying, differential quaternary phase shift keying, are investigated and compared for Rayleigh and Rician fading channels.      In the next paper M.L.R. Khan, M.H. Wondimagegenehu, and T. Shimamura propose an amplitude banded technique with least mean square error on Godard and Sato algorithms for equalization of wireless channels. From mean square error and bit error rate investigations, the nonlinear features of amplitude banded technique are found to yield improved equalization performance and that the Sato algorithm performs better than the Godard technique.      Then, V. Soluk, B.N. Ali, S. Khatun, K.D. Wong and M.A. Mahdi present a new access router discovery method and improved link layer mechanism to enhance seamless vertical handoffs in wireless communication. Analytical and simulation studies are presented in terms of latency and packet loss.      The fifth paper is coauthored by M.T. Hossain, S. Kandeepan, and D. Smith, which investigates the performance of a non-data aided near maximum likelihood estimator for symbol timing recovery in wireless communication system incorporating Rayleigh, Weibull and log-normal fading channels. The bit error rate and error variance performance are evaluated and compared with Cramer Rao bound algorithms.      In the last paper, W. Nasrin and M.M.I. Rajib present analytical and simulation studies on intelligent underlay overlay scheme in enhancing the capacity of global system for mobile communication system. Practical limitations from co-channels, super area coverage, traffic distribution, ratio and speed of moving vehicles, and blocking probability are taken into consideration in the performance evaluation; it shows a 41.42% capacity enhancement over normal cells.      Finally, the Guest Editors would like to express their sincere gratitude to the many reviewers, who have been given immensely to this process. They have responded to the Guest Editors in the shortest possible time and dedicated their valuable time to ensure that the Special Issue contains high-quality papers with significant novelty and contributions. Last but not the least the Guest Editors would extend their appreciation to the Associate Editor-in-Chief, Dr. Haohong Wang for providing them with this opportunity and facilitating preparation of an excellent journal special issue.
['Mohammed Nazrul Islam', 'Mohammad A. Karim', 'Mohammad Abdus Salam', 'Salil Kumar Sanyal']
Guest Editorial - Limitations and Growth of Wireless Communication