Nera WiLink-I 3000, System Manual

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162 Operation
Chapter 4 - Operation and Administration
4.10.4.7 QoS Profiles
The QoS Profile defines the Quality of Service parameters that are applicable when
the QoS Profile is used.
Different QoS Profile Types are available to support different service requirements:
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Real-Time (RT)
service is designed to meet the needs of Real Time Variable Bit
Rate like services characterized by requirements for guaranteed rate and delay
such as streaming video or audio. These services are dynamic in nature, but
offer periodic dedicated requests opportunities to meet real-time requirements.
Because the Subscriber Unit issues explicit requests, the protocol overhead
and latency is increased, but capacity is granted only according to the real
needs of the connection. QoS Profile parameters include Committed
Information Rate (CIR) and Committed Time (CT).
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Non-Real-Time (NRT) service is very similar to the Real-Time polling service
except that connections may utilize random access transmit opportunities for
sending bandwidth requests. These Non Real Time Variable Bit Rate services,
such as file transfer and Internet access with a minimum guaranteed rate, are
characterized by requirement for a guaranteed rate, but can tolerate longer
delays and are rather insensitive to jitter. QoS Profile parameters include
Committed Information Rate (CIR), Committed Time (CT) and Maximum
Information Rate (MIR) that limits the rate so that bandwidth intensive
services will not expand to occupy the full bandwidth.
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Best Effort (BE) service is for services where neither throughput nor delay
guarantees are provided. The Subscriber Unit sends requests for bandwidth in
either random access slots or dedicated transmission opportunities. The
occurrence of dedicated opportunities is subject to network load, and the
Subscriber Unit cannot rely on their presence. Service parameters include
Committed Time (CT) and Maximum Information Rate (MIR).
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Continuous Grant (CG)
service is tailored for carrying constant bit rate (CBR)
real-time services characterized by fixed size data packets on a periodic basis
such as VoIP or E1/T1. The Base Station schedules regularly, in a preemptive
manner, grants of the size defined at connection setup, without an explicit
request from the Subscriber Unit. This eliminates the overhead and latency of
bandwidth requests in order to meet the delay and jitter requirements of the
underlying service. Service parameters include Packet Size (unsolicited grant
size) and Sampling Rate (grant interval).