Browse Prior Art Database

AUTOMATED ROAMING TECHNIQUES FOR WIDE AREA CONVENTIONAL RADIO SYSTEMS

IP.com Disclosure Number: IPCOM000007246D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-07
Document File: 2 page(s) / 126K

Publishing Venue

Motorola

Related People

Thomas E. Weston: AUTHOR

Abstract

Currently, in a wide area, non-simulcast, multi- transmitter, conventional voting system, the only way that a radio user can automatically roam through- out the coverage area of the system is if the mobile or portable is placed in the continuous scan mode. In large systems, frequency re-use may not be possi- ble, and the scan list will grow quite large. It will take far too long for a radio to completely scan through the list. Messages will be lost or severely truncated due to the extreme scan cycle time. Fur- thermore, the only time a scanning radio can truly determine the best site to select is when the system is active with a call. Valuable message content is lost because the radio is in the middle of the site selection process. A better automated roaming tech- nique is needed for large conventional radio systems.

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MOTOROLA Technical Developments Volume22 June 1994

AUTOMATED ROAMING TECHNIQUES FOR WIDE AREA CONVENTIONAL RADIO SYSTEMS

by Thomas E. Weston

the roaming radio to automatically select the best site even during idle system time. Receiver Signal Strength Indication (RSSI), BER, or some other form of carrier to noise analysis can be used to further enhance the final site selection.

INTRODUCTION:

  Currently, in a wide area, non-simulcast, multi- transmitter, conventional voting system, the only way that a radio user can automatically roam through- out the coverage area of the system is if the mobile or portable is placed in the continuous scan mode. In large systems, frequency re-use may not be possi- ble, and the scan list will grow quite large. It will take far too long for a radio to completely scan through the list. Messages will be lost or severely truncated due to the extreme scan cycle time. Fur- thermore, the only time a scanning radio can truly determine the best site to select is when the system is active with a call. Valuable message content is lost because the radio is in the middle of the site selection process. A better automated roaming tech- nique is needed for large conventional radio systems.

  This invention offers a better way to provide auto- mated roaming in a large conventional radio sys- tem. It involves the use of a separate signalling chan- nel at the site and a look-up table in the roaming radio (mobile or portable). This invention will allow

THE BEACON CHANNEL

        Outbound Path The Beacon Channel is the site signaling chan- nel, It is a conventional repeater that continuously transmits a site identifier code using a conventional signaling format such as MDC (see Figure 1). Roaming radio scan lists would be composed ofonly Beacon Channel frequencies instead of actual voice traffic frequencies. The combination of the site iden- tifier code and the Beacon Channel frequency make each Beacon Channel unique, thus Beacon Chan- nel frequencies can be re-used often. This reduces the roaming radio scan list size and cycle time. Bea- con Channels can be shared by all inband users (i.e. one VHF Beacon Channel at a site for all 146-174 MHz radio users).

To User A's System

To User B's System

-11. -.- cs syslem

I

ltl User

User c

A

Figure 1. The Beacon Channel System

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Technical Developments Volume 22 June 1994

  The outbound path of the Beacon Channel will continuously transmit a site identifier code to all roaming radios. The radios will use a look-up table to cross-reference the site identifier code and Bea- con Channel frequency with the appropriate radio mode or Frequency pair that they will use at that site for voice traffic. Look-up tables and Beacon Channel scan lists would be slaved per mode in the radios.

  Roaming radios of a different user organization would be able to share t...