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Browse Prior Art Database

ADAPTIVE POWER CONTROL USING ENCRYPTED UNIT IDS

IP.com Disclosure Number: IPCOM000008248D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-May-30
Document File: 1 page(s) / 69K

Publishing Venue

Motorola

Related People

Victor Veenstra: AUTHOR

Abstract

Portable battery drain is a concern in the design of systems containing hand-held portables. Adaptive Power Control is a means of monitoring and adjusting a portable's transmit power during each portable transmission within an Astro system.

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M-LA Technical Developments

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ADAPTIVE POWER CONTROL USING ENCRYPTED UNIT IDS

by Actor Vsenetra

1. INTRODUCTION

  Portable battery drain is a concern in the design of systems containing hand-held portables. Adaptive Power Control is a means of monitoring and adjusting a portable's transmit power during each portable transmission within an Astro system.

  To assist in the implementation of adaptive power control, the tixed end equipment measures the received signal strength of each portable call in progress. At the end of each portable call, a received signal strength indicator (RSSI) along with the portable's Unit ID (UID) is embedded into a link control message attached to the end of a voted or repeated call. This link control (LC) message is rebroadcast in systems containing repeater or voting operation. After a portable dekeys, the portable "listens" to the channel and receives the LC mes- sage. Once the portable verifies that the UID embedded in the LC message matches its own UID, it determines the transmit power it will use for its next transmission.

2. PROBLEM

  During transmissions, IJIDs are embedded into the transmission at a rate of one per 360 msec. During secure transmissions in which the IJIDs are encrypted, the value of the transmitted UID "changes" every 360 milliseconds due to the

encryption process. Since the fixed end equipment computing the RSSI does not have decryption capa- bility, the unencrypted UID of the transmitting portable cannot be determin...