Examples of such
traffic include various forms for Internet data transfer protocols. In order for SSs
to provide this type of service, the BS provides bandwidth request opportunities to
the SS by means of unicast polling on a regular basis??”at an interval comparable
to 1 sec. Additionally, contention-based broadcast/multicast polling may be used by
the SS to request bandwidth allocations dynamically as needs arise.
?– Best-effort Service (BE) BE, as the name suggests, is designed to transport
data traffic on a best-effort basis with no minimum service level specified. In order
to provide this type of service, SSs use broadcast/multicast polling mechanisms to
request necessary bandwidth. SSs providing this kind of services may also be given
transmission opportunities to request bandwidth using unicast polling.
Multicast Services Being able to provide multicast services so that bandwidth is not
wasted on transmitting identical packets to each and every recipient, is very important
for wireless networks as they have limited transmission resources. Such networks are
routinely expected to use multicast services for applications such as video surveillance,
TV broadcast, online games, or point-to-multipoint virtual LAN services.
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