| The cross-layer design in combining of adaptive modulation and coding with truncated ARQ is now extensively adopted to enhance data rate and quality of transmission in wireless communication systems, which increases spectral efficiency a lot under the premise of ensuring the quality of transmission. In this paper, a adaptive modulation system combined with SR-ARQ is analyzed over Rayleigh fading channels, the main works and innovations of this dissertation are generalized as follows:Firstly, the transmission scheme and the system model of SR-ARQ-AMS over Rayleigh fading channels is analyzed. A finite-state Markov chain modeled for describing Rayleigh fading channels and adaptive modulation system. Secondly, parameterize the factors affecting the system performance and establish a queuing model with vacations by using the equivalent service delay method. The expression. of system's main performance measures, such as system's average waiting delay time and average service delay time are gained, which take into account the delay of lost packet transmitting limited times. The affluence of various system parameters on system delay is analyzed by numerical simulation and then obtains the method to enhance system transmission efficiency. Further more, Multi-state Markov system model is generated after the channel variation state and the number of packets waiting transmission in the buffer is united in G-E channel. The expression of packet loss rate and the steady-state distribution of each system state are gained; the buffer capacity of the communication system is limited actually, so we establish the queuing model M/G/1/K of SR-ARQ-AMS. The estimation method of system packet loss rate gained by using embedded Markov chain. The expression of SR-ARQ-AMS packet loss rate is validated through numerical simulation and analyzes the affluence of various system parameters on system packet loss rate, then obtains the method to enhance system transmission efficiency. |
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