Fair Channel Quality-Based Scheduling Scheme for HSDPA System
Bader Al-Manthari , Nidal Nasser , Hossam Hassanein
1 1 2
1
Telecommunications Research Laboratory
School of Computing, Queen’s University
Kingston, ON, Canada K7L 3N6
{manthari, hossam}@cs.queensu.ca
2
Department of Computing & Information Science
University of Guelph
Guelph, Ontario, N1G 2W1 Canada
nasser@cis.uoguelph.ca
Abstract
Channel dependant scheduling schemes for High
Speed Downlink Packet Access (HSDPA) system such as
Max CIR and Proportional Fairness (PF) have been
proven to provide a significant throughput gain by
exploiting the channel fluctuations of the users. However,
their inability to ensure a fair distribution of the radio
resources among the mobile users has been a major
concern. In earlier study [6], we proposed a Fair and
Efficient Channel Dependent (FECD) algorithm for
HSDPA to provide a priority scheduling between users
based on their instantaneous channel conditions and their
average throughputs. The FECD algorithm aims at
increasing the data rates of the users by exploiting the
variations of their channel conditions while at the same
time ensure a fair distribution of the radio resources. We
evaluated the performance of the FECD algorithm in
Pedestrian A environment. In this paper, however, we
extended our simulation model to include evaluating the
proposed algorithm in Vehicle A environment. Simulation
results show that the proposed algorithm in both
environments outperforms the maximum CIR and the
Proportional Fair schemes in terms of providing
minimum throughput assurance and, therefore, it has a
better degree of fairness.
1. Introduction
The continuous success of mobile communication
systems, as well as its consequences in terms of the need
of better Quality of Service (QoS), more efficient systems
and more services has led to the development of the third
generation (3G) of mobile systems or Universal Mobile
Telecommunications System (UMTS). UMTS promises a
transmission rate of up to 2 Mbps which makes it possible
to provide a global mobility with a wide range of services
including video telephony, paging, messaging, Internet
access and broadband data. However, it is excepted that
there will be a strong demand for multimedia applications
which require higher data rates above 2 Mbps in cellular
systems, especially in the downlink, where users will
enjoy high-speed Internet access and broadcast services.
To boost the support for such high data rates, High Speed
Downlink Packet Access (HSDPA) has been introduced
in release 5 of UMTS [1]. HSDPA promises a
transmission rate of up to 10 Mbps five times greater than
that of 3G/UMTS systems. In HSDPA, high-speed packet
transmission is possible by code or/and time sharing a
data channel among access users. This channel is called
High-Speed Downlink Shared Channel (HS-DSCH).
UMTS already includes a downlink shared channel but
HSDPA extends this concept to provide significantly
higher throughput and, hence, more efficient use of the
radio spectrum.
Within the UMTS architecture, Radio Resource
Management (RRM) entity is responsible for utilization
of the air interface resources, covering packet scheduling,
handoff management and admission control. With the
introduction of HSDPA, better RRM techniques are
needed to improve system performance by maximizing
the overall system capacity and maintaining the QoS of
multimedia traffic. In this paper we investigate the packet
scheduling technique for HSDPA system.
A Packet scheduler (PS) controls the allocation of
channels to users within the coverage area of the system
by deciding which user should transmit during a given
time interval. Therefore, to a large extent; the PS
determines the overall behavior of the system. One
important factor that has been added to the scheduling
problem in HSDPA is the channel conditions of the users.
The scheduling algorithm in HSDPA should track the
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