The Research On Delay Of Cooperative Diversity Network

Multi-input multi-output(MIMO) technology is the most effective way to combatmultipath fading in wireless communications, it is also the reliable guarantee ofhigher data transfer rates, better communication quality and faster terminal movingspeed for wireless communications systems. However, due to the size, power andother factors, it is difficult to install multiple antennas for mobile terminals, thuslimiting the application of MIMO technology. A new space diversity technology-co--operative diversity technology provides new ideas for the practical use of MIMOtechnology. In wireless environment, the single antenna portable mobile node canshare the resources of other nodes to build number of communication link betweenthe source node and destination node; it can form a virtual MIMO system to obtainspatial diversity gain.In this paper, a three-node amplify-and-forward (AF) cooperative diversitynetwork model is proposed. We present the randomness of feedback delay analysis forthe proposed model which the source transmits a frame over Nakagami-m fadingchannel. At the physical layer, due to the time variability of the wireless channel,adaptive modulation and coding (AMC) technique is being used in the source node ofthe analytical model which allows multi-rate transmission of the data frame, thetransmitted mode is chosen according to the channel conditions. Based on the abovereasons, we analyze the steady distribution of the feedback delay, and a Finite StateMarkov Model is developed to evaluate performance the Nakagami-m channel andobtain the channel state transition matrix. Then we derive the transition probability ofthe feedback delay in the proposed model. The simulative results are compared withthe theoretic results; the results verify that the theoretic analysis is correct. Finally,we characterize the effect of channel fading coefficients and maximum frame errorrate on the probability distribution of the feedback delay performance.We present a queuing model for performance analysis of go-back-N automaticrepeat request (GBN-ARQ) protocols in wireless networks using dynamic radio linkadaptation. We propose a Markov-based model, which the transmission usingamplify-and-forward cooperative diversity at the physical layer and a flow controlprotocol, infinite transmitting buffers, and an ARQ-based error recovery mechanismat the radio link layer. This model first considers the characteristic of the wireless channel is time-varying, it can reduce the system performance, and spectrumresources are increasingly strained. We present the state transition model under thelink adaptive condition. On the basis, we establish Markov model of system stateswhile the feedback delay is random variable. The exact queue length and delaystatistics for the GBN-ARQ protocol can be obtained by using matrix geometricmethods under random feedback delay values. We validate the analysis by simulation.The delay statistics obtained in this paper enables us to design wireless systems understatistical delay constraints and would be useful to predict the higher layer protocolperformance.