Communication Protocols And Algorithms For Wireless Concurrent Transmission With Interference Management Supporting

In recent years, along with the rapid proliferation of mobile and smart network-enable wireless devices, wireless networks are widely adopted in both military and civil areas. However, the available wireless network technologies cannot meet the progressively increasing application requirements, in terms of transmission performance, reliability and scalability, etc. Therefore, the study of improving the capability of concurrent communication in wireless networks is an important and urgent work.While the co-channel interference induced by concurrent transmissions will disturb the correct reception of wireless signals, which severely limits the concurrent number of wireless transmissions, and becomes the key factor to restrict the transmission capacity of model wireless communication networks. The interference management technology, represented by interference cancelation and multi-input multi-output(MIMO), is a new and promising progress in the wireless physical layer, by which the interfered packets can be decoded successively from the collision signal and the transmission performance of wireless communication is enhanced significantly. It is a huge breakthrough over the classic designs in the aspect of wireless communication. But the application of interference management in wireless concurrent communication needs the corresponding transmission protocols and scheduling algorithms, such as channel resource allocation, link scheduling, energy saving, and distributed strategies.This thesis investigates the key problems related to wireless concurrent communication by the numbers:(a) in the wireless networks with interference management supporting, study the establishment of novel interference models and signal reception models to settle for the requirements, restrictions and objections of wireless concurrent communication;(b) by using of interference management, design and optimize transmission protocols & scheduling algorithms for enhancing wireless concurrent communication. The main contributions are summarized as follows:(1) To solve the packet collision issue in wireless networks, this thesis introduces a novel collision resolution method based on the technique of known interference cancellation(KIC), and proposes a new MAC protocol named as CR-MAC, in which AP tries to decode all the collided data packets by combining the partial retransmissions mechanism and KIC operations. As the collided transmissions are fully utilized, less retransmission is required, especially in a crowded network. By using the developed classic Bianchi and Malone models, we analyze and validate the performance of CR-MAC protocol under saturated and unsaturated traffic scenarios, respectively. The experimental results show that, under various network settings, CR-MAC performs much better than the IEEE 802.11 DCF in terms of the aggregation throughput and the expected packet delay.(2) Successive interference cancellation(SIC) is an effective way to combat interference at the physical layer. This thesis investigates the joint optimization issue of link scheduling and power control for capacity maximization in SIC-enable wireless networks. We propose a new interference model, named as SIC-PHY, based on the physical interference model to characterize the sequential detection nature of SIC, and hereby design an algorithm, named as LTC-EA, to evaluate the link transmission capacity in a given concurrent link set. Afterwards, we formulize the joint optimization problem by using the mathematic programming method. As the formulized capacity maximization problem, CMP-SIC, is proofed to be a NP-hard problem, we propose a novel approximation approach, GA-SIC, based on the genetic algorithm. Finally, we discuss the design and parameter setting of the GA-SIC, and validate the performance by extensive simulations.(3) This thesis investigates the problem of the minimum length link scheduling(MLLS) in multiuser MIMO(MU-MIMO) networks. As in the networks with MU-MIMO capability, link interference is no longer binary but demonstrates a strong correlation among multiple links, which cannot be captured by the conventional conflict graph interference model. Hence, we propose a novel hypergraph interference model, named as HG-MI, to accurately and efficiently characterize the relationship of multiple interferences induced by concurrent transmissions, and provide a tractable formalization of the minimum length link scheduling in MU-MIMO networks(MU-MIMO MLLS). Afterwards, we prove that the formulized MU-MIMO MLLS problem, HG-MU MLLS, is NP-hard and design two approximation algorithms to find the near-optimal feasible schedule. Finally, extensive simulation experiments are presented.(4) This thesis investigates the design of energy-efficient routing protocols for battery-limited mobile ad hoc networks, considering the energy-consuming MIMO techniques are employed. There are several challenges in such a design: first, it is difficult to characterize the energy consumption of a MIMO-based link; second, without a careful design, the broadcasted RREP packets, which are used in most energy-efficient routing protocols, could flood over the networks, and the destination node cannot decide when to reply the communication request; third, due to node mobility and persistent channel degradation, the selected route paths would break down frequently and hence the protocol overhead is increased further. To address these issues, in this paper, a novel Greedy Energy-Efficient Routing(GEER) protocol is proposed:(a) a generalized energy consumption model for the MIMO-based link, considering the trade-off between multiplexing and diversity gains, is derived to minimize link energy consumption and obtain the optimal transmit model;(b) a simple greedy route discovery algorithm and a novel adaptive reply strategy are adopted to speed up path setup with a reduced establishment overhead;(c) a lightweight route maintenance mechanism is introduced to adaptively repair or rebuild the broken links. Extensive simulation results show that, in comparison with the conventional solutions, the proposed GEER protocol can significantly reduce the energy consumption.In summary, by combing the emerging technology of interference management in wireless communication, this thesis proposes a novel method to embrace interference and enhance concurrent transmissions, which is a great breakthrough over the classic designs based on the idea of interference and collision avoidance. Due to the brilliant potential to improve the network performance, interference management is expected to be used widely in future, and the proposed models and technical solutions in this thesis can provide a guide and reference role to the related designs.