| 概要： |
The need for wireless communications has ever more increased during the
last few years, due to the accelerated growth of the number of consumers
and emergence of broadband services such as high speed internet access
or real-time video applications. In this context, one of the main
challenges of the next generation wireless communication system is to
provide high data rate services, anytime anywhere.
In this talk, we will present some basic component technologies
envisioned for the 4^th Generation (4G) system. After briefly presenting
Orthogonal Frequency Division Multiplexing (OFDM) transmission
technology at the physical layer, we will mainly focus on the radio
resource allocation and scheduling aspects in a multi-user communication
system. Allocation and scheduling are highly complex problems as radio
resources such as time, frequency or code, should be allocated to many
competing users, in a way that optimizes the spectral efficiency of the
system, while guaranteeing the Quality of Service (QoS) requirements of
each individual user but also providing fairness among users. Moreover,
wireless channels undergo rapid variations in the order of milliseconds,
a phenomenon known as fading which is a particular source of difficulty
for radio resource allocation. We present the main issues faced by the
problem of allocation and scheduling in a wireless multiuser system, and
describe the main existing and proposed algorithms.
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