Floor Control Latency Compensation in Push-to-Talk Systems
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Solution Overview
Problem
In push-to-talk (PTT) systems, users connected to low latency networks have an advantage over those on high latency networks when competing for floor control, leading to unfair access due to latency differences.
Innovation Solution
An interoperability and collaboration system, such as Cisco's IPICS, estimates and accounts for transmission delays across high latency links to equalize the probability of granting floor control, preempting local users if necessary to ensure fair access for remote users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If floor control requests are processed in strict chronological order of receipt, then local users on low latency networks gain floor control advantage, but remote users on high latency networks suffer unfair access disadvantage
Solution Approach 1:
The system performs preliminary estimation of network latency for each endpoint before processing floor control requests. By calculating expected transmission times in advance and using these estimates to adjust request timing evaluation, the system compensates for latency differences before they affect floor control allocation decisions
Solution Approach 2:
The system changes the evaluation parameter from absolute receipt time to adjusted timing that accounts for network latency. By modifying how request timing is measured and compared (subtracting estimated latency from receipt time), the system creates a fairer comparison that levels the playing field between local and remote users
2Reliability
If the system compensates for latency by preempting floor control from local users, then remote users gain fair access, but system complexity increases due to timing estimation and preemption logic
Solution Approach 1:
The system implements a feedback mechanism where latency estimates are continuously refined based on actual network performance. By monitoring real transmission times and adjusting estimates accordingly, the system improves accuracy over time while maintaining a relatively simple processing framework
Solution Approach 2:
Each endpoint effectively serves its own timing needs by having the system calculate its specific latency estimate based on its network characteristics. This distributed approach to timing management reduces the burden on the central server while ensuring accurate latency compensation for each user
Data Source
AI summary
Methods and apparatus for assigning floor control based upon when a floor control request was initiated are disclosed. In one embodiment, a method includes receiving a first request for floor control from a first endpoint and granting the floor control to the first endpoint. The method also includes receiving a second request for floor control from a second endpoint, that has approximately the same priority level as the first endpoint, and determining if the first request was initiated from the first endpoint at approximately the same time or earlier than the second request was initiated from the second endpoint. If it is determined that the first request was not initiated from the first endpoint at approximately the same time or earlier than the second request was initiated from the second endpoint, then floor control is preempted from the first endpoint and granted to the second endpoint.