Browse Prior Art Database

Call Prioritization That Compensates For Network Delays

IP.com Disclosure Number: IPCOM000004777D
Original Publication Date: 2001-May-17
Included in the Prior Art Database: 2001-May-17
Document File: 5 page(s) / 29K

Publishing Venue

Motorola

Related People

Colin Chisholm: AUTHOR

Abstract

Communication systems targeted to emerging markets typically have to rely on intersite communication links with slow and often disparate link speeds. This can result in unequalized message transport delays between various points in the system, which can in turn lead to unfair call prioritization when a distributed system architecture is employed. This paper presents an approach that compensates for the variation in message transport delays in a distributed low tier communication system, allowing all end users to receive fair access to the offered services.

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CALL PRIORITIZATION THAT COMPENSATES FOR NETWORK DELAYS

by Colin Chisholm

ABSTRACT

Communication systems targeted to emerging markets typically have to rely on intersite communication links with slow and often disparate link speeds. This can result in unequalized message transport delays between various points in the system, which can in turn lead to unfair call prioritization when a distributed system architecture is employed. This paper presents an approach that compensates for the variation in message transport delays in a distributed low tier communication system, allowing all end users to receive fair access to the offered services.

PROBLEM STATEMENT

Low tier communication systems have special constraints to deal with. Frequently, such systems are forced to support low performance (and hence possibly slow) intersite links. The implementation often requires a distributed architecture to avoid the potentially high hardware costs and poor price scalability of a centralized infrastructure. The lack of the star topology found with a centralized

approach results in the potential for a wide variation of network delay times for messages

traversing the multisite, distributed architecture network. This can cause unfair call prioritization due to delay differences.

PROPOSED SOLUTION

The invention is one that relies on the presence of a relatively accurate time reference at each RF site in the network for time stamping purposes. Note that in many systems a very accurate time source is readily available since GPS receivers are used at each site to provide a timing reference.

The invention modifies the way the system determines the priority of users looking to obtain either talk permit privileges (for a call already underway), or resources for a new call when none are presently available (i.e. when call queueing is occurring). The system no longer determines priority based simply on which request message is seen first by the relevant control entity. Instead, a timestamp is added to certain call control messages traversing the network. The system considers up to three factors before assigning resources to users: the timestamp values in these call control messages; the delays in the intersite transport network; and the history of events in a call. Based on consideration of these factors, the system may grant privileges to users other than by looking at which request was received first. The invention works to more equitably grant resource access privileges and the only expense incurred is an occasional delay in granting permission.

The specifics of the invention are highlighted in the example scenario that follows.

EXAMPLE SCENARIO

Overview

This scenario brings out the pertinent details of both the problem as well as the proposed solution using an example system implemented in a distributed fashion (no centralized switching function). T...