User's Manual Part 1

Release8OverviewofCycloneNetworks
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Issue2,November2007 Draft5forRegulatoryReview 84
Figure 19: TDD dividing Cyclone frames
7.1.7 MaximumInformationRate(MIR)Parameters
Cyclone point-to-multipoint links use the following four MIR parameters for bandwidth
management:
• Sustained Uplink Data Rate (kbps)
• Uplink Burst Allocation (kb)
• Sustained Downlink Data Rate (kbps)
• Downlink Burst Allocation (kb)
You can independently set each of these parameters per AP or per SM.
Token Bucket Algorithm
The Cyclone software uses a token bucket algorithm that
• stores credits (tokens) for the SM to spend on bandwidth for reception or
transmission.
• drains tokens during reception or transmission.
• refills with tokens at the sustained rate set by the network operator.
For each token, the SM can send toward the network in the uplink (or the AP can send
toward the SM in the downlink) an equivalent number of kilobits. Two buckets determine
the permitted throughput: one in the SM for uplink and one in the AP for downlink.
The applicable set of Uplink Burst Allocation and Downlink Burst Allocation
parameters determine the number of tokens that can fill each bucket. When the SM
transmits (or the AP transmits) a packet, the equivalent number of tokens is removed
from the uplink (or downlink) bucket.
Except when full, the bucket is continuously being refilled with tokens at rates that the
applicable set of Sustained Uplink Data Rate and Sustained Downlink Data Rate
parameters specify. The bucket often drains at a rate that is much faster than the
sustained data rate but can refill at only the sustained data rate. Thus, the effects of the
allocation and rate parameters on packet delay are as follows:
• the burst allocation affects how many kilobits are processed before packet delay
is imposed.
• the sustained data rate affects the packet delay that is imposed.