Abstract-This paper proposes a new

Abstract-This paper proposes a new medium access control
protocol for wireless data communications in local area, called
the reservation-based multiple access with variable frame length
( ~ ~ VW)e .de sign RMAV under the consideration that the
population of wireless terminals and the system load frequently
change and are almost unpredictable in wireless data "munications.
RMAV is based on the slot reservation schenle and
adopts a frame structure with variable length. The frame length
increases as the number of active terminals and/or the system load
increases. We evaluate the performance of RMAV by analysis and
computer simulation. Due to its adaptability to traffic patterns,
RMAV offers short delay in light load conditions and high
throughput in heavy load conditions.
I. INTRODUCTION
N THE OFFICE and factory automation, wireless access
to data communication networks can provide more flexible
and convenient user interfaces [l], [2]. Also, in data
communications with portable computers, wireless access can
guarantee the movability of portable devices. A wireless access
system (WAS) for local data communications consists of,
as in voice communications, one base station and several
wireless terminals. The base station is a part of a fixed
backbone network that can be any of the following: lwal
area networks (LAN's), metropolitan area networks (MAN'S),
wide area networks (WAN'S), and their combinations. The
wireless terminals are computers or computerized devices. In
WAS with a star topology, the base station and the terminals
communicate with each other using two logically separated
channels. The base station uses the downward channel to
broadcast control traffic and/or information traffic to terminals,
while the terminals use the upward channel to transmit their
traffic to the base station. Since the base station is a unique
transmitter using the downward channel, the base station can
appropriately schedule the transmission of its traffic. On the
other hand, the upward channel is shared among all terminals,
and a multiple access protocol is needed. In this paper we focus