Research On QoS Guarantee Routing In Ad-hoc Networks Based On Cooperative Communication

Wireless ad-hoc network is one of the core access technologies to realize Internet of Things and Ubiquitous Networks, and this makes the subject become a key research issue. If we want to implement a wireless ad-hoc network, routing is one of the most elementary problems. The function of routing is to send data generated by sources to destinations with the help of other nodes. So a good routing scheme can improve the data transmission performance, which is a determining factor of network performance. On the other side, when we do research on wireless transmission, the effect of wireless signal delegation should not be avoided, since this effect can reduce the network perfor-mance. For now, one of strategies is to use the technology of Multi-Input Multi-Output (MIMO). Such kind of technology can alleviate this delegation effect greatly and im-prove the network performance. So with the aim of conquering these disadvantages and making full use of existing network, cooperative communication is provided. Without the requirement of other hardware, we can increase wireless transmission gain with the help of a virtual MIMO system.We know that one of the weaknesses is the instability. This makes that it is very important to design routing protocols which can guarantee the low packet drop loss ra-tio. Meanwhile, some resources in wireless ad-hoc network are limited, such as node energy and link bandwidth. In such kind of environment, how to make full use of MI-MO and cooperative communication rises. Our work tries to answer this question, and there are four research points in this thesis:1) a transmit antenna selection problem for MIMO wireless ad-hoc networks in lossy environment;2) an energy-efficient op-portunistic relay assignment problem in wireless cooperative networks;3) an incentive energy-efficient data gathering problem in wireless cooperative networks;4) a truth-ful and capacity-aware routing problem in wireless cooperative networks. The main contributions of our network are as follows.1A transmit antenna selection problem for MIMO wireless ad-hoc networks in lossy environmentIn our thesis, we investigate how to select part of transmit antennas for data trans-mission while guaranteeing a certain packet drop loss ratio from any node to the sink. We prove that this problem is NP-hard, and propose a transmit antenna s-election problem based on greedy strategy. The correctness of this algorithm is provided. Also, we analyze the message complexity. Numerical results show that this algorithm can reduce transmission energy greatly.2An energy-efficient opportunistic relay assignment problem in wireless co-operative networks To make great use of this mechanism, it is very important to assign proper re-lays to transmission pairs. In practical environment, the packet drop can lead to a lot of data retransmission and waste too much energy. In such kind of scenario, we investigate how to assign proper relays to transmission pairs with the aim of energy-efficiency. Because the problem is NP-hard, a distributed opportunistic relay assignment algorithm is proposed, and we analyze the approximate per-formance ratio of this algorithm and its message complexity. Simulation results shows the efficiency of this algorithm.3An incentive energy-efficient data gathering problem in wireless cooperative networks In energy-constrained wireless ad-hoc networks, it is one of the most important issues to select energy-efficient paths from source nodes to the sink for data gath-ering. Cooperative communication can provide energy-efficiency, and one of the fundamental assumptions is that each node is unselfish, responsible and willing to forwarding data. However, in energy-constrained environment, because of limit-ed energy, each node hates participating in data transmission without any incen-tive. In this thesis, we will propose a utility function to stimulate nodes to behave unselfishly. Base on this function, an energy-efficient data gathering problem in wireless cooperative networks is investigated. Because of its NP-hardness, we design a heuristic algorithm to solve this problem, and analyze the approximate performance ratio of this algorithm. Simulation results shows that in a100node network, the averaged saved energy when each node takes a selfish behavior, is52.5%less than the average when nodes behave unselfishly.4A truthful and capacity-aware routing problem in wireless cooperative net-works We will investigate how to select forwarding nodes and cooperative relay nodes for data transmission between sources and destinations in wireless selfish net- works. To make sure each node can behave honestly, a reward-efficient mecha-nism is designed, and we prove that if we use this mechanism, unselfishness and truthful can be guaranteed. Moreover, in order to solve this NP-hard problem, we propose a relay node assignment algorithm whose aim is to maximizing the minimal path capacity. Its approximate performance ratio is2. Simulation results show that the minimal capacity can be increased by14.42%.