Chapter 1: Product description
Wireless operation
Link mode optimization
Link mode optimization allows the PTP 650 link to be optimized according to the type of traffic that
will be bridged. The link supports two modes, IP Traffic and TDM Traffic.
IP traffic
IP Traffic mode is optimized to provide the maximum possible link capacity. IP Traffic mode is an
appropriate choice where applications in the bridged networks provide some measure of reliable
transmission, and where very low latency is not critical. IP mode supports both fixed and adaptive
link symmetry (see
TDM traffic
TDM Traffic mode is optimized to provide the lowest possible latency. TDM Traffic mode
additionally implements a more conservative approach to adaptive modulation, leading to lower
error rates in fading channels at the expense of slightly lower link capacity. TDM Traffic mode is an
appropriate choice for delay intolerant data without reliable transmission (for example voice over
IP data).
Link symmetry
The PTP 650 series provides four configuration options for apportioning the available capacity
between the two link directions.
•
Symmetric – The Master and Slave have equal capacity. The PTP 650 series achieves this by
allocating an equal Burst Duration for the Master and the Slave.
•
2:1 – The capacity in the direction Master to Slave is twice that of the direction Slave to Master.
The PTP 650 series achieves this by setting the Burst Duration of the Master to twice that of the
Slave.
•
1:2 – The capacity in the direction Slave to Master is twice that of the direction Master to Slave.
The PTP 650 series achieves this by setting the Burst Duration of the Slave to twice that of the
Master.
•
Adaptive – This is only available on the Full variant. The capacity allocated to a given link
direction is dependent on the offered level of network traffic in both link directions. If the level
of offered traffic in both directions is equally high or equally low, the PTP 650 will allocate
equal capacity to both directions. If however the offered level of traffic is greater in one
direction, it is allocated a greater proportion of the overall link capacity. The PTP 650 series
achieves this by increasing (or decreasing) the duration of the Transmit Burst in a given link
direction as the offered level of network traffic increases (or decreases) in this same direction.
This is done independently for the two directions.
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