Scheduling and Flow Control Mechanisms for Multihop Wireless Networks

• Main Authors: Ping-Chen Lin, 林昞辰
• Other Authors: Ray-Guang Cheng
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/9t397b

博士 === 國立臺灣科技大學 === 電子工程系 === 102 === Multihop wireless technology is one of the solutions proposed to improve the transmission rate of the next-generation wireless networks. This dissertation investigates the impact of the multihop wireless architecture on the widely used Wi-Fi and LTE-A technologies. The first part of the dissertation studied the Wi-Fi-based multihop wireless backhaul networks. In such networks, the end-to-end throughput of the network decreases as the length of the backhaul network increases; and the throughput of a relay node depends on its location, which is also known as a ‘parking-lot problem.’ We adopted a Ripple protocol to enhance the throughput of relay nodes and proposed a two-level quality of service (QoS) scheduler to solve the parking-lot problem and to guarantee the QoS of each user. A queueing model was presented to analyze the end-to-end throughput and mean delay of the multihop wireless backhaul networks and the accuracy of the proposed model was verified by computer simulations. The second part of the dissertation investigated an LTE-A relay network. In LTE-A relay network, the base station is not aware of users’ channel qualities served by a relay node. The mismatch of the data rates between the access link and the relay link may result in buffer-overflow for some users while buffer-underflow for the other users served by the same relay node. A dynamic flow control algorithm (DFCA) was proposed to minimize the buffer-overflow and buffer-underflow probabilities. The proposed DFCA is designed to minimize the feedback signaling overhead by dynamically adjusting the window size and the feedback frequency based on relevant measure obtained from individual user. The third part of the dissertation considered the packets forwarding between two relay nodes in an LTE-A relay network for a mobile user during handover. Pre-buffering scheme is a solution adopted by the relay nodes to reduce the number of forwarding packets. However, it was found that improper flow control scheme may severely degrade the performance of the pre-buffering scheme. A pre-buffering-aware flow control scheme (PFCS) was presented to reduce the number of forwarding packets and increase the system throughput by solving buffer-underflow and buffer-overflow problems.