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CENTRALIZED HETEROGENEOUS SYSTEM HANG TIME DETERMINATION AND DISTRIBUTION BETWEEN A WLAN SYSTEM AND A LEGACY WIDE AREA SYSTEM

IP.com Disclosure Number: IPCOM000008991D
Original Publication Date: 2002-Jul-29
Included in the Prior Art Database: 2002-Jul-29
Document File: 3 page(s) / 42K

Publishing Venue

Motorola

Related People

Joseph Phillips: AUTHOR [+3]

Abstract

In a WLAN system used for voice communication, bandwidth could become limited because of the loading of many users. Users may experience degraded one-to-many dispatch performance if the bandwidth is no longer available to enable continuity of conversation. In particular, a first user would key up and transmit to his user group. The first user then de-keys. A second user wants to reply. The response could be delayed or may not be completed in a timely manner. This problem is further complicated when a wide area dispatch system is added that has wide area subscriber components that are also members of the dispatch group. The real problem here is how to initiate and manage dispatch hang time in such a system.

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CENTRALIZED HETEROGENEOUS SYSTEM HANG TIME DETERMINATION AND DISTRIBUTION BETWEEN A WLAN SYSTEM AND A LEGACY WIDE AREA SYSTEM

By: Joseph Phillips, Randy Ekl and Michael Retzer

 
 


THE PROBLEM

In a WLAN system used for voice communication, bandwidth could become limited because of the loading of many users.   Users may experience degraded one-to-many dispatch performance if the bandwidth is no longer available to enable continuity of conversation.   In particular, a first user would key up and transmit to his user group.  The first user then de-keys.   A second user wants to reply.   The response could be delayed or may not be completed in a timely manner.   This problem is further complicated when a wide area dispatch system is added that has wide area subscriber components that are also members of the dispatch group.   The real problem here is how to initiate and manage dispatch hang time in such a system.

THE SOLUTION

One possible solution to this problem would be to have the last talker, upon PTT release, send hang time to the central controller that also functions as a gateway to a foreign system with members of the group.   If another user takes up the conversation floor, the user terminal must send in a hang time cancel message to the gateway.   If the hang time expires, the central gateway sends an end of call to all users on both systems.   If a wide area member of the group keys up, the gateway device routes the call to the LAN embodiment of the group.   This may be a VOIP conference ID, or simply an RTP session with a unique session ID for the group.   Either way, the call is routed to members of the group on the multi-access LAN and to the WLAN as required by group membership.    When the wide area member de-keys, the gateway detects it and creates a hang timer for the group.   The gateway also sends out idle messages or voice prompts to members of the group on the LAN/WLAN side of the system.  The hang timer selected matches the hang timer used by the wide area system.   This could either be Radio Service Software programmed elements in the wide area subscriber units or system wide parameters programmed into the Wide Area System component.   If the hang timer expires, the Gateway sends a hang timer expire message to LAN/WLAN members of the group.     A message may not be sent to the wide area system since it is maintaining a hang timer by traditional means.    If provisions exist for external hang timer input into the Wide Area System, an appropriate hang timer expire message will be sent from the Gateway to the Wide Area System for completeness and to ensure against race conditions.

The system controller function on the LAN side of the system could be a different component.   In this case, the Gateway only functions as the interface between the Wide Area System group member and the LAN portion of the system.  

Figure 1 depicts a system (100) that contains one or more wired segment (101), WLAN segments (150, 151) and one or more traditional wireless wide area segments  (320).   Th...