在OPNET平台上建立了DMR(Digital Mobile Radio)集群基站控制信道随机接入的模型,并根据DMR空口协议各种呼叫类型的空口占用特点及其发生概率,对随机接入中的各种退避算法进行了仿真,比较了线性退避算法和二进制退避算法,通过仿真得出...在OPNET平台上建立了DMR(Digital Mobile Radio)集群基站控制信道随机接入的模型,并根据DMR空口协议各种呼叫类型的空口占用特点及其发生概率,对随机接入中的各种退避算法进行了仿真,比较了线性退避算法和二进制退避算法,通过仿真得出在二进制退避算法下,DMR集群控制信道中的随机接入具有更好的吞吐率和延时等综合性能。展开更多
In this paper, an adaptive random access strategy is presented for multi-channel relaying networks to address the issue of random access of the non-real-time （NRT） services. In the proposed scheme, NRT services acce...In this paper, an adaptive random access strategy is presented for multi-channel relaying networks to address the issue of random access of the non-real-time （NRT） services. In the proposed scheme, NRT services access the base station （BS） by first accessing the nearest relay node （RN）. When collision occurs, for the sake of fast and efficient access, the user will begin a frequency domain backoff rather than randomly retry in time domain. A remarkable feature of this scheme is that the RN will adaptively determine the maximum allowed frequency backoff window at each access period. This is achieved according to the new arrival rate as well as the number of available access channels. Moreover, to alleviate the interference caused by sub-channel reuse among RNs, a fractional frequency reuse scheme is also considered. The analysis and numerical results demonstrate that our scheme achieves higher throughput, lower collision probability and lower access delay than conventional slotted Aloha as well as the scheme without frequency backoff window adaptation.展开更多
The Probability Distribution of. Slot Selection (PDoSS) of IEEE 802.11 DCF is extremely uneven, which makes the packet collision probability very high. In this paper, the authors explore how to make the stations selec...The Probability Distribution of. Slot Selection (PDoSS) of IEEE 802.11 DCF is extremely uneven, which makes the packet collision probability very high. In this paper, the authors explore how to make the stations select:the slots uniformly, and give an RWBO(P-d,w) algorithm for 802.11 DCF to make the PDoSS even and decrease the packet collision probability. A Markov model is given to analyze the PDoSS of RWBO(p(d), w). The performance of RWBO(p(d), w) is evaluated, by. simulation in terms of saturation throughput and packet collision probability. The simulation results indicate that RWBO(p(d), w) can decrease the packet contention,probability to a large extent, and utilize the channel more efficiently as compared to the 802.11 DCF. Moreover, the relation between saturation throughput, and walking probability (p(d)),the relation between saturation throughput and contention windows (w), the relation between packet collision probability and walking probability (p(d)), and the relation between packet collision probability and contention windows (w) are analyzed. The analysis indicates that RWBO(p(d), w) has some remarkable features: its saturation throughout keeps high and packet collision probability keeps very low (under 0.1) in a large range of p(d) and w, which allow users to configure p(d) and w more flexibly.展开更多
文摘在OPNET平台上建立了DMR(Digital Mobile Radio)集群基站控制信道随机接入的模型,并根据DMR空口协议各种呼叫类型的空口占用特点及其发生概率,对随机接入中的各种退避算法进行了仿真,比较了线性退避算法和二进制退避算法,通过仿真得出在二进制退避算法下,DMR集群控制信道中的随机接入具有更好的吞吐率和延时等综合性能。
基金Supported by the National High-Tech Research & Development Program of China (Grant No. 2009AA01Z262)the National Basic Research Program of China (Grant No. 2009CB320400)the National Natural Science Foundation of China (Grant No. 60832009)
文摘In this paper, an adaptive random access strategy is presented for multi-channel relaying networks to address the issue of random access of the non-real-time （NRT） services. In the proposed scheme, NRT services access the base station （BS） by first accessing the nearest relay node （RN）. When collision occurs, for the sake of fast and efficient access, the user will begin a frequency domain backoff rather than randomly retry in time domain. A remarkable feature of this scheme is that the RN will adaptively determine the maximum allowed frequency backoff window at each access period. This is achieved according to the new arrival rate as well as the number of available access channels. Moreover, to alleviate the interference caused by sub-channel reuse among RNs, a fractional frequency reuse scheme is also considered. The analysis and numerical results demonstrate that our scheme achieves higher throughput, lower collision probability and lower access delay than conventional slotted Aloha as well as the scheme without frequency backoff window adaptation.
文摘The Probability Distribution of. Slot Selection (PDoSS) of IEEE 802.11 DCF is extremely uneven, which makes the packet collision probability very high. In this paper, the authors explore how to make the stations select:the slots uniformly, and give an RWBO(P-d,w) algorithm for 802.11 DCF to make the PDoSS even and decrease the packet collision probability. A Markov model is given to analyze the PDoSS of RWBO(p(d), w). The performance of RWBO(p(d), w) is evaluated, by. simulation in terms of saturation throughput and packet collision probability. The simulation results indicate that RWBO(p(d), w) can decrease the packet contention,probability to a large extent, and utilize the channel more efficiently as compared to the 802.11 DCF. Moreover, the relation between saturation throughput, and walking probability (p(d)),the relation between saturation throughput and contention windows (w), the relation between packet collision probability and walking probability (p(d)), and the relation between packet collision probability and contention windows (w) are analyzed. The analysis indicates that RWBO(p(d), w) has some remarkable features: its saturation throughout keeps high and packet collision probability keeps very low (under 0.1) in a large range of p(d) and w, which allow users to configure p(d) and w more flexibly.
