Research On Effective Transmission Schemes In Multiple Layer Heterogeneous Wireless Communication Networks

After the commercial deployment of the fourth generation mobile communication system, the next gen-eration mobile communication system has attracted increasing attention of researchers, which brings new challenges in the field of user experience rate, mobility, end-to-end latency, connection density, traffic den-sity and so on. To satisfy these requirements, technologies such as low-complexity beamformingj large-scale antennas, full duplex, multiple layer networks, interference management and wireless power transfer and so on are supposed to be introduced. This thesis focuses on effective transmission schemes in multiple layer heterogeneous networks. For multiple layer heterogeneous networks with relay, small cell and device-to-device (D2D) nodes, considering antenna selection, full duplex and energy harvesting, the research of the thesis includes performance analysis of antenna selection for two-way relay in Nakagami-m fading chan-nel, performance analysis of antenna selection for two-way full duplex amplify-and-forward relay network-s, performance analysis of heterogeneous networks with interference cancellation, performance analysis of relay-aided heterogeneous networks with interference cancellation, performance analysis of multiple antenna selection with quality-of-service (QoS) constraints in D2D networks, performance analysis of relay-aided networks with simultaneous wireless information and power transfer. The main contributions of this thesis are listed as follows:1. We investigate the performance of multi-antenna two-way relay networks, where both amplify-and-forward (AF) and decode-and-forward (DF) relaying strategies are considered. An antenna selection scheme among all nodes is proposed based on maximizing the worse received signal-to-noise ratio (S-NR) of two end users, and the performance of the system is analyzed based on the proposed scheme. We derive the probability density function (PDF) and cumulative distribution function (CDF) of the received SNRs of both users. We also obtain the closed-form expressions of average bit error rates (BER) and the outage probability of our system. The results show that the proposed antenna selection scheme achieves full diversity, and the simulation results closely match to our theoretical analysis. To further improve the spectrum efficiency of the system, a hybrid selection antenna scheme is proposed. Finally, the numerical results show that our scheme outperforms the state of art.2. The antenna selection of a massive multiple-input-multiple-output (MIMO) network with two-way ful-1 duplex relay is investigated and the performance of the system is analyzed, where the worse receive signal-to-noise ratio (SNR) of the base station and the user is maximized. We first derive the approximate probability density function (PDF) of receive SNR for two users. Then the overage outage probability and bit error rate of the network are obtained. When the number of antennas at the base station approach-es to infinity, we also obtain the asymptotic expression of the overall outage probability. It is shown by simulation that our analytical result is efficient in estimating the network reliability, especially in the high transmit SNR region.3. We investigate the performance of relay-aided networks and propose time allocation scheme for two hops DF relay networks and relay selection scheme for two way AF relay networks, where both wireless infor-mation and power transfer are considered. First we derive the cumulative distribution function (CDF) of the received SNRs in two-hops decode-and-forward relay system with energy harvesting relay, and obtain the asymptotic expressions of the outage probability of the system, which show the relationship among the outage probability, full energy harvesting slots and the power splitting factor. Based on the derivation results, we proposed a quality of service (QoS) constraint based time allocation scheme. Then we proposed three relay selection schemes based on receive SNR maximization, energy harvesting maximization and weighted relay selection for two way amplify and forward relay system with energy harvesting end nodes. The proposed schemes enhance the transmission quality of the system as well as the energy requirement of the energy harvesting nodes.4. We study the downlink outage performance of heterogeneous cellular networks with an interference can-cellation scheme employed at macro base station, which aims to eliminate the cross-tier interference from macro base station to small cell users. The downlink performance of heterogeneous cellular networks is in-vestigated. Expressions of the Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of the received SNRs of both macro and small cell users are derived and closed-form expressions of overall outage probability of the system are provided. Analytical results and simulations both show that the overall performance of the heterogeneous cellular networks is improved with interference cancellation.5. We investigate the downlink performance of heterogeneous networks (HetNet), where both direct and relay-aided transmission strategies in a macro cell are considered. An interference cancellation scheme employed at macro base stations is first proposed based on the cancellation of cross-tier interference from the macro base station to small cell users. Then, we derive the expressions of the probability density function (PDF) and cumulative distribution function (CDF) of the received SNRs of both macro and small cell users, and provide the closed-form average bit error rate (BER) and overall outage probability of the system. We show that the SNR boost at the small cell mobile stations comes from the cancellation of the cross layer interference by the macro base station. Therefore the performance of the small cell is improved greatly with interference cancellation, while the overall performance of the HetNet is also ameliorated. The numerical results finally show the validity of our analysis.6. The multiple antenna selection at base station in D2D cellular networks is investigated, where more than one antenna participates in the data transmission. The performance of the system is analyzed and a multiple antenna selection based on QoS constraint is proposed. By deriving the probability density function (PDF) and cumulative density function (CDF) of the receive signal of the active user and D2D user respectively, the overall outage probability of the D2D system is obtained. With the derivation results, a QoS based multiple antenna selection scheme is proposed to further improve the energy efficiency at the base station of the D2D system, where the number of selected transceiver antennas is determined by both of the QoS constraint and transmit signal-to-noise ratio (SNR). Finally, the Monte Carlo simulation results show the accuracy of the derivation in the paper and the advantage of proposed scheme to the best antenna selection.