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|Title: ||Topology control in wireless mesh networks with directional antennas|
|Other Titles: ||Pei zhi ding xiang tian xian wu xian wang luo de tuo pu kong zhi|
|Authors: ||Zheng, Zhongming (鄭忠明)|
|Department: ||Department of Computer Science|
|Degree: ||Master of Philosophy|
|Issue Date: ||2010|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Wireless communication systems.|
|Notes: ||CityU Call Number: TK5103.2 .Z46 2010|
ix, 55 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2010.
Includes bibliographical references (leaves 50-55)
|Abstract: ||With the development of wireless networks, many studies have been done to
improve the network performance. Among those studies, wireless mesh networks
have become a hot research interest in recent years. A wireless mesh network is an
infrastructure wireless network composed by gateway nodes, non-gateway nodes
and end-users. The back bone of the mesh networks is formed by gateway nodes
and non-gateway nodes with wireless links. Gateway nodes connect to Internet
by wired links. The end users directly connect with mesh back bone by wireless
links, and access the Internet by mesh back bone.
We found that only limited studies about topology control by using directional
antennas have been done. One interesting study to optimize performance by using
directional antennas was proposed by Kumar et al. In their work, a topology control
algorithm was presented to create a tree with bounded degree, based on the
approximation algorithm of minimal degree spanning tree. However, the throughput
is not the direct objective in their algorithm, which means that their algorithm
may not be optimal in throughput.
Based on the work of Kumar et al, we formulate the throughput of each node as
traffic delivery ratio. With each node equipped with m non-steerable directional antennas, two topology control algorithms for the wireless mesh networks are
presented . Our objective is to maximize the minimal traffic delivery ratio from
each node to the gateway nodes in both algorithms, by adjusting the orientations
of the directional antennas appropriately.
The MTDR (maximizing traffic delivery ratio) algorithm is based on an approximating
degree bounded algorithm. In every step, the algorithm chooses a
pair of links to be added and removed, so that the number of the maximal degree
nodes is decreased by one. Then, the maximal degree of the topology will
be decreased gradually until it is equal or smaller than the number of equipped
directional antennas. We show by simulation that the MTDR algorithm improves
the throughput significantly, compared with Kumar et al’s work. Moreover, we
study how each parameter, such as the beam width of antennas, and the number
of antennas on each node, has impact on the network performance.
Many advantages of directional antennas are not utilized in the MTDR algorithm.
We have improved our topology control method and proposed the EMTDR
(extended maximizing traffic delivery ratio) algorithm for the single channel wireless
mesh networks with m directional antennas equipped on each node. The objective
of the EMTDR algorithm is the same as the MTDR algorithm. By allowing
each antenna to connect to multiple nodes, the EMTDR algorithm improves performance
by 40% ~ 280%, compared with the MTDR algorithm.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b3947828|
|Appears in Collections:||CS - Master of Philosophy |
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