计算机工程
計算機工程
계산궤공정
COMPUTER ENGINEERING
2014年
7期
37-41
,共5页
TCP Westwood协议%部分可观测马尔可夫决策过程%频谱感知%Sarsa(λ)算法%TCP吞吐量%感知时间
TCP Westwood協議%部分可觀測馬爾可伕決策過程%頻譜感知%Sarsa(λ)算法%TCP吞吐量%感知時間
TCP Westwood협의%부분가관측마이가부결책과정%빈보감지%Sarsa(λ)산법%TCP탄토량%감지시간
TCP Westwood(TCPW) protocol%Partial Observable Markov Decision Process(POMDP)%spectrum sensing%Sarsa(λ) algorithm%TCP throughput%sensing time
目前针对认知无线电网络中TCP协议的研究大多假设次用户的感知是完美的，且未综合考虑TCP协议参数和感知时间等因素对TCP性能的影响。针对上述问题，在TCP Westwood协议的基础上，提出一种基于传输预判的改进TCP协议，建立基于认知无线电网络的TCP吞吐量跨层模型。采用部分可观测马尔可夫决策过程对有感知误差的次用户频谱感知和接入过程进行建模，将其转换为信念状态马尔可夫决策过程，使用Sarsa(λ)算法对其进行求解，以在最大化TCP吞吐量的同时得到最优感知时间。仿真结果表明，与TCP Reno和TCP Newreno协议相比，使用该方案所得的TCP拥塞窗口值分别提高约42%和27%，平均吞吐量分别提高约5.7%和5.5%，当感知时间为0.2 s时，所得的TCP平均吞吐量为最大值。
目前針對認知無線電網絡中TCP協議的研究大多假設次用戶的感知是完美的，且未綜閤攷慮TCP協議參數和感知時間等因素對TCP性能的影響。針對上述問題，在TCP Westwood協議的基礎上，提齣一種基于傳輸預判的改進TCP協議，建立基于認知無線電網絡的TCP吞吐量跨層模型。採用部分可觀測馬爾可伕決策過程對有感知誤差的次用戶頻譜感知和接入過程進行建模，將其轉換為信唸狀態馬爾可伕決策過程，使用Sarsa(λ)算法對其進行求解，以在最大化TCP吞吐量的同時得到最優感知時間。倣真結果錶明，與TCP Reno和TCP Newreno協議相比，使用該方案所得的TCP擁塞窗口值分彆提高約42%和27%，平均吞吐量分彆提高約5.7%和5.5%，噹感知時間為0.2 s時，所得的TCP平均吞吐量為最大值。
목전침대인지무선전망락중TCP협의적연구대다가설차용호적감지시완미적，차미종합고필TCP협의삼수화감지시간등인소대TCP성능적영향。침대상술문제，재TCP Westwood협의적기출상，제출일충기우전수예판적개진TCP협의，건립기우인지무선전망락적TCP탄토량과층모형。채용부분가관측마이가부결책과정대유감지오차적차용호빈보감지화접입과정진행건모，장기전환위신념상태마이가부결책과정，사용Sarsa(λ)산법대기진행구해，이재최대화TCP탄토량적동시득도최우감지시간。방진결과표명，여TCP Reno화TCP Newreno협의상비，사용해방안소득적TCP옹새창구치분별제고약42%화27%，평균탄토량분별제고약5.7%화5.5%，당감지시간위0.2 s시，소득적TCP평균탄토량위최대치。
Most of the existing studies about TCP protocol in Cognitive Radio(CR) network assume that the Secondary User(SU)’s perception is perfect. These studies also do not consider the TCP protocol parameters and sensing time’s influence on the TCP performance. To solve the above problems, this paper proposes an improved TCP protocol which has the transmission pre-judgment ability based on the TCP Westwood(TCPW) protocol. It builds the cross-layer TCP throughput model on the basis of CR networks. Due to the perception errors of secondary user, its spectrum sensing and access problem is modeled as a Partial Observable Markov Decision Process(POMDP) which is then converted to belief state Markov Decision Process(MDP), with the Sarsa(λ) algorithm to achieve the solution of Belief State Markov Decision Process(BMDP) model. It can achieve the optimal sensing time while TCP throughput has the maximum value. Simulation results show that the TCP congestion window value obtains with this scheme is about 42%more than using the TCP Reno protocol, and is about 27%more than using the TCP Newreno protocol. The average throughput obtains with this scheme is about 5.7% higher than using TCP Reno, and is about 5.5%higher than using TCP Newreno. When the sensing time is 0.2 s, the resulting TCP average throughput is the maximum.
