Performance Analysis And Optimized Design Of The Vehicular Mobile Communication Networks In Interference Scenarios

With the rapid development of the communication technology and the traffic, it should be noted that, the vehicular mobile communication networks, as an important application of fifth generation (5G) wireless systems, have attracted more attention of the public than ever before. In the fut,ure vehicular mobile communication, the user of the dense network should be guaranteed to obtain the bigger transmission rate in lower delay constraint, moreover, the various needs of service should be satisfied. As the increase of the number of the vehicular users, the receiver is affected by the co-channel interference with a higher probability during the message delivery. Base on the interference and node mobility, in the thesis, it is assumed the interference is in high mobility, that is, the new interference will be generated in every time slot, then the performance analysis and the optimized design of the vehicular communication network are carried out.Firstly, in this thesis, the highway scenario is considered, that is, the nodes including the, source, the relays and the destination are mobile along the highway. It is assumed that the interference is highly mobile, i.e., a new Poisson point process (PPP) is drawn in each time slot. The relay is affected by the noise without the interference, and the destination is under interference-limited scenario, that is the effect of the interference is much larger than that of the noise. Based on the model, the exact expression of the outage probability and the lower bound are derived. The impacts of the first hop and the second hop on the end-to-end outage probability are analyzed. Moreover, how the outage probability varies is given when the source, relay and destination are mobile. When the sum of the transmitting power at the source and the relay is constrained by a constant,the optimal power allocation is obtained to minimize the end-to-end outage probability.Secondly, the end-to-end delay of the multi-hop mobile communication networks is analyzed, and the optimum number of hops that minimizes the end-to-end delay is derived.In most of the previous works in the delay analysis, it is assumed that the relay nodes are equidistant to each other on the line connecting the source and the destination, and the impact of the number of hops on the delay is ignored. The increase of the number of hops means that the distance of one hop decreases, which is beneficial to improve the communication quality and decrease the delay, however, it will result in more co-channel interference, which will be adverse to improve the communication quality and will increase the delay. In this thesis, three distributions of the relay nodes are considered in the delay analysis and optimized design of the multi-hop wireless networks, which include the equidistant case, the uniform case and the random waypoint mobility (RWPM) model case. When the received signal-to-interference ratio (SIR) for the interference-limited systems is same to the received signal-to-noise ratio (SNR) for the noise-limited systems,the comparison of the delay of the single hop transmission between these two systems is carried out. The end-to-end delay of the system with equidistant, relays is compared with the system with uniformly-located relays, and it is obtained that the end-to-end delay of the equidistant case is smaller than that of the uniform case. The uniform distribution of the relay location is used to model the system with stationary relays, and the RWPM model is used to model the system with mobile relays. By comparing the systems with these two distributions, the impacts of the node mobility on the end-to-end delay are analyzed. The results indicate that the mobile relays can effectively decrease the delay of the multi-hop wireless networks.Thirdly, the full connectivity is analyzed for the systems under interference-limited scenario, moreover, the impact of the node mobility on the connectivity probability is investigated. In most of the previous works in connectivity analysis, it is assumed that during the message delivery, the interference is ignored, and the impacts of the node density and the node mobility on the connectivity probability are not included. If the interference is considered in the system analysis, the increase of the node density means that the inter-node distance decreases, which leads to a stronger desired signal at the receiver and is beneficial to the increase of the connectivity probability, however, it will result in the stronger interference, which is adverse to improve the communication and connectivity probability. Based on this motivation, in the thesis, the upper bound and the lower bound to the connectivity probability are derived for the interference-limited scenario. And it is verified by the analysis and the simulation that the full connectivity probability is quasi-concave function with node density, which is the same to the moti-vation. For the mobile wireless networks, the impacts of the average speed on the full connectivity probability of the linear network in the finite segment are analyzed.Fourthly, in the thesis we consider the single hop transmission with a random mul-tiple access protocol, the random access transport capacity (RATC) of the half-duplex system and the full-duplex system are derived. It is assumed that the receiver chooses its first neighbor as the transmitter, thus, the distance between the transmitter and the receiver is a random variable rather than a constant. For the transmission probability, a higher transmission probability means the transmitter has more opportunities to deliver a message, which will be good for improving the RATC. However, a higher transmission probability will result in the increase of the number of the interference at the receiver, then the successful probability of a. transmission becomes lower and the RATC may decrease.Similarly, on the one hand, when the SIR threshold increases, the transmission rate will be improved, which is beneficial to the increase of RATC. On the other hand, increasing SIR threshold means the successful probability of one transmission will be lower, which will be bad to increase the RATC. By the simulation and the analysis results, it is indi-cated that RATC of single hop transmission is a quasi-concave function with transmission probability, SIR threshold.Finally, the throughput of the multi-hop systems employing decode-and-forward (D-F) is analyzed and the optimum design for the systems to maximize the throughput is obtained. In most of the previous work in the throughput analysis, only one optimized pa-rameter maximizing the throughput is obtained, and the jointly optimization parameters that maximizes the throughput are not given. In the thesis, the relationship between the number of hops, the SIR threshold and the throughput of the multi-hop wireless networks is analyzed. When one of these two system parameters is fixed and given, the throughput is a quasi-concave function with the other parameter. By the special structure of the throughput expression, the jointly optimized parameter vector is obtained to maximize the throughput.