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Browse Prior Art Database

OPTIMAL DROP-OUT TIME PREDICTION METHODS

IP.com Disclosure Number: IPCOM000008537D
Original Publication Date: 1998-Mar-01
Included in the Prior Art Database: 2002-Jun-21
Document File: 4 page(s) / 229K

Publishing Venue

Motorola

Related People

Gabor Seymour: AUTHOR

Abstract

In group dispatch systems with message trunking transmission, the duration of the drop-out time can be provisioned as shorter or longer than an optimal value. If it is too short, significant network resources may be wasted for re-establishing the continuation of the same group call as a new call. If it is too long, the original group call is tying up network resources for longer than needed. As a result, the network throughput can be far less than optimal, especially when short group calls dominate.

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0 M MO-LA

Technical Developments

OPTIMAL DROP-OUT TIME PREDICTION METHODS

by Gabor Seymour

THE OPTIMIZATION CHALLENGE

  In group dispatch systems with message trunking transmission, the duration of the drop-out time can be provisioned as shorter or longer than an optimal value. If it is too short, significant network resources may be wasted for re-establishing the continuation of the same group call as a new call. If it is too long, the original group call is tying up network resources for longer than needed. As a result, the network throughput can be far less than optimal, especially when short group calls dominate.

  Existing private trunking systems are either transmission trunking systems with no drop-out time or they provide a predetermined and fixed drop-out time value.

THE OPTIMIZATION APPROACH

  The probability and the most likely duration of the pauses in the dispatch call can be predicted based on the historical activity in the current and previous, similar group calls. Then, the drop-out time duration can be continuously adjusted based on these predictions.

  The Zone Controller unit or another node in the network is enhanced for collecting statistics on the activities of the talkgroup members. The correlation analysis on the collected statistics can be performed as a background activity.

  In addition, a correlation can also be established between the probability distribution of the pause duration and some historical parameters in the calls before the occurrence of the pause. These parame- ters may include the probability and the delay of the response to a particular member's activity in general or in one specific talkgroup.

THE OPTIMIZATION GAIN

  An example of the distribution of the pause duration and the related, possible drop-out values can be illustrated as follows:

  The drop-out threshold value T,, represents a fixed setting as it is applied in currently deployed systems. It is most likely different from the optimum settings that may vary depending on the network utilization optimization criteria.

  The gain in network utilization can be quanti- tied in the following example. If an average call lasts 100 Set, the G fixed drop-out time setting is 8 set and the 'f. optimal drop-out time 4 set, then overall network utilization gain from switching from T,, to T. is 4%. An opposite example is when the average call setup throughput is 1000 calls per minute, the fir fixed drop-out time setting is 4 set and the T0 optimal drop-out time is 8 set and then after switching from T,, to TO, the optimized call- setup throughput will increase to 1040 callslmin.,
i.e. by 4%.

  Consequently, the optimization criteria should define a weighted balance between the value of saving idle network connection and eliminating superfluous call setups.

0 Motomla. 1°C 1998 27 March 1998

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MOTOROLA Technical Developments

  The implementation of the adjustments in the TU, threshold value can adv...