Fine-grained and Lightweight Control for Future High Speed Wireless Networks

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Fine-grained and Lightweight Control for Future High Speed 
        Wireless Networks"

By

Miss Lu WANG


Abstract

Wireless penetration has witnessed explosive growth over the last two decades. 
Accordingly, wireless devices have become much denser per unit area, resulting 
in an over-crowded usage of wireless resources. To avoid radio interferences 
and maximize the channel capacity, wireless stations have to exchange control 
messages to coordinate well. The existing wisdoms of conveying control messages 
consume valuable communication resources, and introduce massive coordination 
overheads. Therefore, how to provide cost-effective coordination mechanisms 
becomes a critical problem in wireless design.

In this thesis, we first present a survey on the recent advances in wireless 
communications, including a variety of PHY and MAC layer coordination 
mechanisms, and reviews of classic problems in wireless networks.

The state-of-the-art expensive coordination mechanisms motivate us to propose a 
novel PHY layer technique termed Attachment Transmission. It provides an extra 
control panel with minimum overhead. In a traditional transmission paradigm, 
control messages compete for communication resources with data packets.  On the 
contrary, attachment transmission enable control messages to be transmitted 
along with data packets, without degrading the effective throughput of the 
original data packets.

To demonstrate the effectiveness of the attachment transmission, we apply it to 
a number of classic problems in wireless networks, including the multi-channel 
allocation problem in OFDMA-based networks, the hidden and exposed terminal 
problem in ad-hoc networks, and the multiple access problem in wireless local 
area networks (WLAN). Extensive experiments demonstrate that attachment 
transmission is capable of exploiting channel redundancy to deliver control 
information, thus provides significant support to numerous higher layer 
applications.

In addition to attachment transmission, we further exploit OFDM subcarriers for 
fine-grained and lightweight control, termed subcarrier control. Subcarrier 
control is categorized into two kinds: subcarrier coordination for cogitative 
radio networks (CRNs) and subcarrier coding for wireless rate adaptation (WRA). 
Subcarrier coordination moves cooperative sensing and multi-channel contention 
from time domain into frequency domain, which significantly reduce the control 
overhead. Subcarrier coding aims to conduct fine-grained rate adaptation at 
subcarrier level, and thus approaches the channel capacity. We validate 
subcarrier control through extensive experiments, and discuss potential 
research directions of fine-grained and lightweight control over wireless 
communications.


Date:			Wednesday, 8 January 2014

Time:			9:30am – 11:30am

Venue:			Room 3501
 			Lifts 25/26

Chairman:		Prof. Vladimir Chigrinov (ECE)

Committee Members:	Prof. Mounir Hamdi (Supervisor)
 			Prof. Gary Chan
 			Prof. Jogesh Muppala
 			Prof. Khaled Ben Letaief (ECE)
                        Prof. Hussein Mouftah (Elec. Engg. & Comp. Sci.,
 					       Univ. of Ottawa)


**** ALL are Welcome ****