A framework for performance evaluation and functional verification in stochastic process algebras
Proceedings of the 2008 ACM symposium on Applied computing
Wireless Personal Communications: An International Journal
Optimum multichannel random access with retransmission cut-off in OFDMA wireless systems
Proceedings of the 11th international symposium on Modeling, analysis and simulation of wireless and mobile systems
A Service-Differentiated Random Access Strategy for Multi-channel Cooperative Relaying Networks
Wireless Personal Communications: An International Journal
Computer Networks: The International Journal of Computer and Telecommunications Networking
OFDMA-based medium access control for next-generation WLANs
EURASIP Journal on Wireless Communications and Networking - Special issue on OFDMA architectures, protocols, and applications
IEEE Transactions on Wireless Communications
WOCN'09 Proceedings of the Sixth international conference on Wireless and Optical Communications Networks
International Journal of Mobile Network Design and Innovation
Opportunity detection for OFDMA-based cognitive radio systems with timing misalignment
IEEE Transactions on Wireless Communications
An OFDM based MAC protocol for underwater acoustic networks
Proceedings of the Fifth ACM International Workshop on UnderWater Networks
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Orthogonal frequency-division multiple access (OFDMA) systems are considered promising candidates for implementing next-generation wireless communication systems. They provide multiple channels that can be accessed via random access schemes. However, traditional random access schemes could result in an excessive amount of access delay. To address this issue, we develop a fast retrial scheme that is based on slotted Aloha and exploits the structure of OFDMA. A salient feature of this scheme is that when collisions occur instead of retrials occuring randomly in time, they occur randomly in frequency, i.e., the scheme randomly selects the subchannels for retrial. To further achieve fast access, retrials are designed to follow the 1-persistent type, i.e., no exponential backoff. To achieve the maximum throughput, we limit the maximum number of allowed retrials according to the load condition. We also consider the issue of designing for an appropriate reuse factor for random access channels in order to overcome the intercell interference problem in OFDMA multicell environments. Our finding is that full sharing, i.e., a reuse factor of one, performs best for given random access channels. Through analysis and simulation, we confirm that our fast retrial algorithm has the advantage of high throughput and low access delay, and the full sharing policy for random access channels shows high throughput as well as low collision.