User's Manual

Document Number: 0100SM1401 Issue: 10-14

•Radios which detect reduced QoS

(Quality of Service) can increase

reliability by dynamically reducing

their RF speed to the base station.

•Sites which are not impacted by

reduced QoS remain unchanged.

•Older technology does not have the

ability to monitor the radio link QoS

or dynamically adjust the over the air

data rate, which can result in loss of

communications.

Part D – Feature Detail

Dynamic speed selection derives QoS from both RSSI (Received Signal Strength) and ARQ performance in order to maintain a

radio link operating at the fastest speed possible for the given quality of the link.

Each radio stores a table of destination MAC addresses vs fastest RF speed in a dynamic speed cache, using information learned

from previous transactions over the air. In this way, the radio dynamically learns what RF speed should be chosen for a transmission.

Should the transmission generate an ARQ, the radio will drop down in RF speed to improve reliability of data delivery.

In the event that radio has not yet learnt the fastest RF speed for a destination MAC, the message will be transmitted out at

the slowest RF speed in the given bandwidth, to provide the highest sensitivity, and therefore the highest reliability.

As broadcast and multicast addresses are potentially destined for multiple radios these types messages will always be

transmitted at the slowest speed. The following diagrams show how the RF data rate can be influenced by obstructions:

Dynamic Speed - With Obstructions

Old Technology - With Obstructions