The Interference Mitigation And Spatial Sharing Technology In60GHz Millimeter Wave Wireless Personal Area Networks

With the development of wireless communication, new applications such as uncompressed high definition video transmission and massive downloading require the data rate to achieve a gigabit magnitude. Research shows that such data rate could not be met under spectrum shortage even with the high spectral efficiency technologies, which makes the high frequency communications become inevitable. Recently, many countries have opened their frequency band from57GHz to66GHz. The continuous9GHz bandwidth provides endless possibility for the realization of high speed wireless communications, which attracts extensive attention from academic and industrial areas. Furthermore, the development of radio frequency front end technologies such as Complementary Metal-Oxide-Semiconductor Transistor (COMS) promote the millimeter wave wireless communications becoming the most favorable candidate of short distance wireless communications.The features of60GHz frequency band determine the directional antennas are needed to compensate for the high propagation loss and application scenarios are mainly focused on the indoor line of sight high speed transmissions. It is of great importance to support the access and transmission of multiple links in those dense scenarios. However, the channel plan implies only2channels are available in most of countries. Hence, appropriate access and scheduling mechanisms to improve spatial sharing are the key problems in enhancing network capacity. Meanwhile, concurrent transmissions in the dense network lead to excess co-channel interference, which greatly limits the network performance. Thus, interference mitigation mechanism is necessary. In this dissertation, the spatial sharing and interference mitigation technologies in mm Wave WPANs are studied and new solutions are proposed. The performance of the heuristic and optimal algorithms aiming at achieving spatial sharing gain and the feasibility of virtual relay on interference mitigation are verified by establishing a reasonable mathematical model and extensive computer simulation. The main contributions of this dissertation are listed as below:1) Firstly, the interference sensing beamforming mechanism which integrates the interference measurement with beamforming is proposed to collect the co-channel interference with less measurement overhead. Then, conflict graph is introduced to uniform the interference between links and weight constraint is derived to reflect the spatial sharing conditions under physical interference model. The optimization problem of maximizing coexist link number in all the service periods is decomposed into a sequence of subproblems which maximize coexist link number in every single service period respectively. As a solution, the maximum coexistence possibility algorithm is proposed. Finally, simulations demonstrate that the maximum coexistence possibility algorithm outperform blind algorithm and maximum sector different algorithm in spatial sharing gain. In addition, we also analyze and compare the computation complexity of those algorithms.2) The spatial sharing conditions under physical interference model and half duplex constraints are derived. With consideration of different traffic load on links, the optimization problem aiming at maximizing spatial sharing gain in mmWave WPANs is formulated as the minimum length scheduling problem. Column generation which is suit for large scale linear programming is adopted to decompose the original problem to restricted master problem and pricing subproblem. To evaluate the spatial sharing gain under different conditions, power control and rate daptation mechanisms are integrated in the subproblem. The IBM ILOG ODM Enterprise version3.7is chosen as the solver to evaluate the spatial sharing gain under different mechanism and antenna configurations.3) The effects of multi-hop architecture on spatial sharing and interference mitigation are evaluated. Under the physical interference model, the spatial sharing conditions are first derived when the non-PCP devices act as the relay device in the millimeter wave wireless personal area networks. Then, with the consideration of different traffic load on each link, the optimal scheduling problems under single and multi-hop architecture are formulated as minimum length scheduling problems. The column generation algorithm and IBM ILOG ODM Enterprise3.7are adopted as the solver to obtain the optimal solutions under single hop and multi-hop millimeter wave wireless personal area networks. Simulations demonstrate the spatial sharing enhancement brought by multi-hop architecture. The effects of interference mitigation and network performance enhancement of virtual relay are demonstrated in60GHz office environment.