The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving...The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving state to transmitting state, and the time for the radio to sense the carrier. The analysis shows that these parameters are the main factors deteriorating the performance of the protocols, especially for CSMA. The multichannel mode efficiently decreases the effects of these factors and the system capacity is changeable conveniently. Comparing curves and some simulation results are given.展开更多
Considering that weak channel collision detection ability, long propagation delay and heavy load in LEO satellite communications, a valid adaptive APRMA MAC protocol was proposed. Different access probability function...Considering that weak channel collision detection ability, long propagation delay and heavy load in LEO satellite communications, a valid adaptive APRMA MAC protocol was proposed. Different access probability functions for different services were obtained and appropriate access probabilities for voice and data users were updated slot by slot based on the estimation of the voice traffic and the channel status. In the proposed MAC protocol limited wireless resource is allocated reasonably by multiple users and high capacity was achieved. Three performance parameters: voice packet loss probability, average delay of data packets and throughput of data packets were considered in simulation. Finally simulation results demonstrated that the performance of system was improved by the APRMA compared with the conventional PRMA, with an acceptable trade-off between QoS of voice and delay of data.展开更多
This study proposes a new multiple access con-trol protocol named distributed synchronous reservation mul-tiple access control protocol,in which the hidden and exposed terminal problems are solved,and the quality of s...This study proposes a new multiple access con-trol protocol named distributed synchronous reservation mul-tiple access control protocol,in which the hidden and exposed terminal problems are solved,and the quality of service(QoS)requirements for real-time traffic are guaranteed.The protocol is founded on time division multiplex address and a different type of traffic is assigned to different priority,according to which a node should compete for and reserve the free slots in a different method.Moreover,there is a reservation acknowledgement process before data transmit in each reserved slot,so that the intruded terminal problem is solved.The throughput and average packets drop probability of this protocol are analyzed and simulated in a fully connected network,the results of which indicate that this protocol is efficient enough to support the real-time traffic,and it is more suitable to MANETs.展开更多
文摘The performance of ALOHA, Non-Persistent CSMA protocols and their slotted versions in Packet Radio Network is analyzed in consideration of the time of propagation delay, the time of radio transformation from receiving state to transmitting state, and the time for the radio to sense the carrier. The analysis shows that these parameters are the main factors deteriorating the performance of the protocols, especially for CSMA. The multichannel mode efficiently decreases the effects of these factors and the system capacity is changeable conveniently. Comparing curves and some simulation results are given.
文摘Considering that weak channel collision detection ability, long propagation delay and heavy load in LEO satellite communications, a valid adaptive APRMA MAC protocol was proposed. Different access probability functions for different services were obtained and appropriate access probabilities for voice and data users were updated slot by slot based on the estimation of the voice traffic and the channel status. In the proposed MAC protocol limited wireless resource is allocated reasonably by multiple users and high capacity was achieved. Three performance parameters: voice packet loss probability, average delay of data packets and throughput of data packets were considered in simulation. Finally simulation results demonstrated that the performance of system was improved by the APRMA compared with the conventional PRMA, with an acceptable trade-off between QoS of voice and delay of data.
基金supported by the National Natural Science Foundation of China(Grant Nos.60372048,60496316)the Hi-Tech Research and Development Program of China(No.2005AA123910).
文摘This study proposes a new multiple access con-trol protocol named distributed synchronous reservation mul-tiple access control protocol,in which the hidden and exposed terminal problems are solved,and the quality of service(QoS)requirements for real-time traffic are guaranteed.The protocol is founded on time division multiplex address and a different type of traffic is assigned to different priority,according to which a node should compete for and reserve the free slots in a different method.Moreover,there is a reservation acknowledgement process before data transmit in each reserved slot,so that the intruded terminal problem is solved.The throughput and average packets drop probability of this protocol are analyzed and simulated in a fully connected network,the results of which indicate that this protocol is efficient enough to support the real-time traffic,and it is more suitable to MANETs.
