Browse Prior Art Database

MULTI-STAGE SLOT SYNCHRONIZATION SCHEME FOR APC025 SLOTTED ALOHA

IP.com Disclosure Number: IPCOM000008803D
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-15
Document File: 2 page(s) / 85K

Publishing Venue

Motorola

Related People

Michael L. Johnson: AUTHOR [+3]

Abstract

In the APCO 25 implementation of Slotted ALOHA on the trunking control channel, a sub- scriber unit must synchronize to the outbound con- trol channel (CC) prior to sending any transmission on the inbound control channel. In order to maxi- mize control channel throughput, it is critical to cor- rectly obtain synchronization so as to not collide with other users on the inbound control channel. At the same time, it is imperative that the subscriber obtain slot synchronization on the outbound control channel as quickly as possible upon arriving on this channel to enable the subscriber to register on the inbound channel.

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MO-LA Technical Developments

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MULTI-STAGE SLOT SYNCHRONIZATION SCHEME FOR APC025 SLOTTED ALOHA

by Michael L. Johnson, Scott J. Pappas and Robert Rzepiela INTRODUCTION

  In the APCO 25 implementation of Slotted ALOHA on the trunking control channel, a sub- scriber unit must synchronize to the outbound con- trol channel (CC) prior to sending any transmission on the inbound control channel. In order to maxi- mize control channel throughput, it is critical to cor- rectly obtain synchronization so as to not collide with other users on the inbound control channel. At the same time, it is imperative that the subscriber obtain slot synchronization on the outbound control channel as quickly as possible upon arriving on this channel to enable the subscriber to register on the inbound channel.

stage process. In the first step, or the "Acquire" stage, the Subscriber attempts to obtain slot syn- chronization as quickly as possible. The second step or "Confirm" stage, speed is sacrificed slightly in order to obtain extremely reliable synchronization. The third and final step or the "Maintain" stage con- tinuously checks to verify that the current synchro- nization is correct.

Figure 1, below, shows the finite state machine for this process

DESCRIPTION

  Synchronization involves monitoring status symbols in order to determine slot size and slot boundary locations. This is performed in a three

ESTABLISH

passed

Fig. 1 Slot Sync Finite State Machine

Q Motorola. 1°C 1998 53 September I998

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0 M

MOTOROLA Technical Developments

STAGE 1

   In the first step, speed is critical...