Research On Multi-Interface And Multi-Channel Switching Scheme And Dynamic NIC Selection In WLANs

As radio access technology demand a collection of wired or wireless links to transport data traffic between radio station and control center or switching center, and all these links collectively constitute the backhaul network of Radio Access Network. As a result, backhaul network need to meet the requirements of broad bandwidth, low latency and high throughput. With the increment of network’s coverage and traffic load, the traditional backhaul solution that base on xDSL, FTTx and point-to-point microwave backhaul will face the challenge of construction and cost under the circumstance of high-speed data traffic and high-density network coverage. It is well known that point-to-point microwave backhul typically operates in the licensed spectrum which requires the line of sight link. Capacity expansion will face the issue of great expense and poor spectrum. In addition to the time consumption in arrangement, the Fiber-based backhaul is also expensive. However, with the development of wireless local area networks’technologies, WLANs become one of the potential solutions for wireless backhaul networks due to the characteristics such as high data rate, flexible deployment and low cost.How to measure the quality of radio channel and detect the occurrence of interference in time, and at the same time, to choose an appropriate target channel in switching procedure to reduce switching delay and packet loss rate, is a urgent issues. This paper aims at wireless backhaul link scenario and both APs and STAs are equipped with multi-NICs. A multi-interface and multi-channel status detection and switch scheme (MIMC-SDSS) taken into consider both channel quality and traffic load of upper layer is proposed. One of wireless network interface cards is used to be control NIC which detects the interference and calculates the channel priority parameter periodically. The rest of NICs as data NIC are used to transmit data. The channel quality and the traffic load of upper layer are used as the criteria for channel switching operation. The switch will be triggered and the channel with the highest priority factor value will be chosen as the switching channel if the switching threshold is met. Performance simulation results based on NS-3 simulation tool show that the proposed algorithm can significantly reduce the switching delay and alleviate the sharp drop of throughput due to channel switch.Furthermore, because of traffic load possesses characteristics such as burstness and instability, how to decide the number of NICs that used to transmission and rationally allocate load among them upon the variation of upper layer traffic is another significant topic of the present study. This paper investgates a dynamic NIC selection (MIMC-DNS) mechanism based on load-aware. This mechanism can choose the proper number of NICs for data transmission in the light of the workload varying as well as the transmission capacity of NIC. And then according to the average estimate delay of each NIC, the packets would be prorated to the activated data NICs. Performance simulation results reveal that the proposed mechanism does not only dynamically choose appropriate number of NIC for transmission but also improves channel utilization and energy efficiency without decreasing the quality of service.This thesis consists four chapters which are organized as follows:Chapter 1 introduces the basic background of this research, the significance and major work of this thesis in brief. Chapter 2 elaborates on the research status of several multi-channel MAC protocol and channel scanning and switching, and introduces the simulation tool used herein. Besides, the simulation tool used herein is also introduced. Chapter 3 discusses multi-interface multi-channel detection and channel switching mechanism in detail, moreover, the simulation results is also discussed. Chapter 4 investigates dynamic NIC selection mechanism based on multi-interface multi-channel and the performance of the presented algorithm is evaluated using simulations. Finally, the conclusion of the paper and suggestions for future works in this area are available.