Browse Prior Art Database

A METHOD FOR IMPROVED SITE SELECTION IN A CELL-BASED TDMA FAIL-SOFT SYSTEM

IP.com Disclosure Number: IPCOM000008517D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-19
Document File: 2 page(s) / 126K

Publishing Venue

Motorola

Related People

Tom Tyson: AUTHOR

Abstract

The invention is a priority inversion system which allows radio users to override an otherwise effective priority scheme for site selection, when their specific location causes them to be cut off from their talk group. In an iDEN system, a radio is capable of using a site which has lost connection to the network for communications among the cells in that site. The radio is programmed to utilize the network when possible and to only use the non- networked (isolated) site when no networked site is available.

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MOTOROLA Technical Developments

A METHOD FOR IMPROVED SITE SELECTION IN A CELL-BASED TDMA FAIL-SOFT SYSTEM

by Tom Tyson

INTRODUCTION AND BACKGROUND

  The invention is a priority inversion system which allows radio users to override an otherwise effective priority scheme for site selection, when their specific location causes them to be cut off from their talk group. In an iDEN system, a radio is capable of using a site which has lost connection to the network for communications among the cells in that site. The radio is programmed to utilize the network when possible and to only use the non- networked (isolated) site when no networked site is available.

  There are certain regions of a system where the signal from a neighboring site is weak, but usable. In such a region, hilly topology, vegetation, or man- made structures may cause a patchwork of locations where the signal of the neighboring site can be used. These regions would not normally be covered by that neighboring site, but the isolated site, which has a strong signal in these locations, will be ignored whenever the neighbor is usable. Figure 1 illustrates such a situation in which the isolated site is deeply encroached upon by one of its neighbors.

spotty coverage

networked tower

A

isolated tower

0 user position

Fig. 1 Site Selection in Normal Isolated Site Operation

  Radio users in the spotty coverage area will at times be connected to the network, and at other times connected to the isolated site. This is expected to benefit the users who get the network, because they can communicate with any other networked user, but they will not be able to communicate with the users in their talk group still serviced by the iso- lated site. The situation may be as simple as walk- ing to the top of a hill, getting connected to a neigh- bor site, and not being able to talk to an associate

@

still at the bottom of the hill. Walking around the corner of a building, or to a different room or floor of a building, might produce the same effect,

INVENTION

  The solution is to allow users who recognize that they are in a spotty coverage area due to site isolation, to enable a...