Interference aware resource allocation for hybrid hierarchical
wireless networks
q
Preetha Thulasiraman, Xuemin (Sherman) Shen
*
Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
article info
Article history:
Received 15 October 2009
Received in revised form 12 February 2010
Accepted 21 March 2010
Available online 27 March 2010
Responsible Editor: L. Jiang Xie
Keywords:
Interference
Maximum concurrent flow
Spatial reuse
Power
Rate
Multihop cellular networks
abstract
This paper addresses the problem of interference aware resource allocation for OFDMA
based hybrid hierarchical wireless networks. We develop two resource allocation algo-
rithms considering the impact of wireless interference constraints using a weighted SINR
conflict graph to quantify the interference among the various nodes: (1) interference aware
routing using maximum concurrent flow optimization; and (2) rate adaptive joint subcar-
rier and power allocation algorithm under interference and QoS constraints. We exploit
spatial reuse to allocate subcarriers in the network and show that an intelligent reuse of
resources can improve throughput while mitigating interference. We provide a sub-opti-
mal heuristic to solve the rate adaptive resource allocation problem. We demonstrate that
aggressive spatial reuse and fine tuned-interference modeling garner advantages in terms
of throughput, end-to-end delay and power distribution.
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
Broadband wireless access (BWA) networks are de-
signed to provide cellular systems that support fixed and
mobile users with heterogeneous and high traffic rate
requirements. In such networks a single base station (BS)
is deployed to cover a cellular area. In such a large area,
users at the cell edge often experience bad channel condi-
tions. Moreover, in urban regions, shadowing by various
obstacles can degrade the signal quality in some areas.
Increasing the number of base stations is an expensive
solution and increasing the base station power only in-
creases the intercell interference. Deploying relay stations
(RS) is a feasible solution since typical relays are cheaper
than base stations and they do not need their own wired
backhaul, therefore they are easier to deploy. Relaying
technology is increasingly applied to multihop communi-
cation in orthogonal frequency division multiple access
(OFDMA) based BWA networks because of its ability to
provide cost-effective enhancement of coverage, through-
put, and system capacity [1,2]. In OFDMA networks, basic
resources are subcarriers and power. Subcarriers experi-
ence frequency selective fading, which takes different val-
ues for different users and subcarriers. Therefore, optimal
allocation of these resources is crucial in reaching various
objectives such as improving throughput, reducing power
consumption or maximizing fairness.
In multihop wireless networks, interference is seen as a
major limiting factor in the performance of the network.
Interference is quantified through the use of interference
models. The two most prominent models are the protocol
model and the physical model [3]. Graph based approaches
for interference modeling using both of these models have
been developed in [4,5]. An accurate modeling of interfer-
ence is fundamental in order to obtain theoretical and/or
simulation based results of some practical relevance.
1389-1286/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.comnet.2010.03.012
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Parts of this paper have been presented at IEEE ICC 2009 and IEEE
WiMesh 2009.
* Corresponding author. Tel.: +1 519 888 4567x32691; fax: +1 519 746
3077.
E-mail addresses: pthulasi@bbcr.uwaterloo.ca (P. Thulasiraman),
xshen@bbcr.uwaterloo.ca (Xuemin (Sherman) Shen).
URL: http://pthulasi@bbcr.uwaterloo.ca (P. Thulasiraman).
Computer Networks 54 (2010) 2271–2280
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Computer Networks
journal homepage: www.elsevier.com/locate/comnet