Abstract
This paper considers transceiver array-based single-hop
wavelength division multiplexing (WDM) networks with reservation-based packet
scheduling algorithms. In reservation-based packet scheduling algorithms for
single-hop WDM networks, one or more of the wavelengths are used as control
channels for transmitting reservation information. Time on a control channel
is divided into control frames and each control frame is further divided into
control slots. Each node is usually assigned a dedicated control slot in each
control frame. Before transmitting a data packet, a node sends a control packet
in a control slot to all other nodes to reserve a data slot. This paper proposes
to adjust the lengths of the control frames dynamically according to the loads
of the nodes by removing unused control slots. A dynamic control frame structure
with variable number of control slots is proposed. A method is devised to
enable the nodes in the network to dynamically acquire and release control
slots depending on their loads such that the control frames include only necessary
control slots for those nodes that have or potentially have data packets to
send. Therefore, the delays for transmitting control packets and data packets
can be reduced. Dynamically adjusting the lengths of the control frames is
able to reduce the delays for transmitting control packets and data packets
when the network load is light to medium or the traffic pattern is moderately
or highly nonuniform; however, it introduces extra overhead in each control
frame such that the length of the control frame may become larger than the
size of the control frame in the fixed control frame structure resulting in
higher mean packet delay when the load of the network is heavy and the traffic
pattern is uniform or nearly uniform. Therefore, this paper further proposes
a hybrid fixed and dynamic scheme that dynamically employs the fixed control
frame scheme or the dynamic control frame scheme depending on the loads of
the nodes. The performance of the proposed hybrid scheme is studied via simulations.
Our simulation results show that the hybrid scheme is able to dynamically
choose the better of the fixed and dynamic control frame schemes such that
it yields the lowest mean packet delay for the entire range of network loads
and traffic patterns.
© 2008 IEEE
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