On Performance Improvements of Spread Slotted ALOHA Network with CLSP/CC

Tae-Joong KIM  Ki-Jun KIM  Seung-Hoon HWANG  Keum-Chan WHANG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E80-A   No.12   pp.2493-2499
Publication Date: 1997/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Spread Spectrum Techniques and Applications)
spread slotted ALOHA,  CLSP,  CLSP/CC,  network throughput,  

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This paper presents a new CLSP/CC (Channel Load Sensing Protocol/Channel Clearance) in order to obtain better performances in spread slotted ALOHA networks. This protocol can decrease a wasteful utilization of channel by prohibiting continuous transmission of the packets destroyed in previous slot, with little added network complexities. For channel clearance technique, hub station broadcasts NAK to all mobile stations when the number of packets transmitted in a slot exceeds the channel capacity, and mobile stations cease own packet transmissions at NAK broadcast. The performances of the proposed CLSP/CC are obtained and compared with those of conventional CLSP by simulations. The performances include network throughput, average processing time and the number of mobile stations in backlogged state. As simulation results, the proposed CLSP/CC outperforms conventional CLSP, especially in highly offered load environment. Also as the proposed CLSP/CC obtain maximum throughputs at higher offered loads and the larger number of mobile stations in backlogged state than the conventional CLSP, it is found that our protocol can support more mobile stations and higher occurrence probabilities.