This paper examines the retransmission probability and throughput characteristics of slow-frequency-hopping spread spectrum transmission in Rayleigh fading indoor channels of multi-cell environments. Because signal strength in a Rayleigh fading indoor channel changes slowly, retransmission probability is little influenced by the retransmission unit length and error correction capability when retransmission unit length is shorter than the fading period. With the 83.5MHz bandwidth of the 2.4GHz ISM (Industrial, Scientific, and Medical) band in the USA, quaternary phase shift keying (QPSK) is expected to provide a throughput of nearly 1Mbps in each cell when we assume a shadowing margin of 18.1dB and we use 4 cells, 100 hopping frequencies, a transmission power of 600mW, and a transmission distance of 20m. And also with the 26MHz bandwidth of the 2.4GHz ISM band in Japan, QPSK is expected to provide a throughput of nearly 1Mbps in each cell under similar conditions but with 26 hopping frequencies and a transmission power of 260mW.

This paper proposes a request-grant-type multiple access control called bandwidth-request labeled-slot multiple access (BLMA) for wireless LANs. BLMA employs slotted ALOHA in the request stage and has an algorithm to avoid unfair access due to the capture effect in this stage. In BLMA, terminals transmit data using fixed length slots called fragment slots in the transmission stage. The base station assigns the fragment slots one by one to terminals for peer-to-peer communication in which terminals communicate directly. It also controls the retransmission based on the stop and wait automatic repeat request scheme. The base station retransmits data for the source terminal as much as it can. BLMA provides simple and fair access control, efficient link utilization, and easy implementation. It also allows modes to be easily changed automatically from peer-to-peer communication to store-and-forward communication in which terminals communicate via the base station. Design concepts of a wireless MAC discussed and details of BLMA are described. The evaluation results of the BLMA are also shown.