Browse Prior Art Database

DETERMINED PRIORITY S-DSMA CHANNEL ACCESS

IP.com Disclosure Number: IPCOM000007502D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2002-Apr-02
Document File: 4 page(s) / 234K

Publishing Venue

Motorola

Related People

Stanley J. Knapczyk: AUTHOR

Abstract

This invention proposes a channel access algo- rithm that is particularly suited to an integrated voice and data system. In such a system, a balance must be struck between the need for good data through- put and fast voice access. The algorithm described here achieves this balance allowing voice and data users to coexist on the system.

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Page 1 of 4

MOlYlROLA Technical Developments

DETERMINED PRIORITY S-DSMA CHANNEL ;ACCESS

by Stanley J. Knapczyk

PRIOR ART

  This invention proposes a channel access algo- rithm that is particularly suited to an integrated voice and data system. In such a system, a balance must be struck between the need for good data through- put and fast voice access. The algorithm described here achieves this balance allowing voice and data users to coexist on the system.

  The channel access algorithm depicted in Fig- ure 1 and described as prior art is the one currently defined by the APCO PROJECT 25 in the docu- ment Common Air Interface Operation Description For Conventional Systems (Nov. 9, 1993). This channel access algorithm was originally derived from algo- rithms used in data only systems and contains deficiencies when applied to integrated voice/data systems.

  The transmission of a data packet follows a polite procedure which minimizes collisions on the radio channel. This procedure requires that an MR (Mobile Radio) wait until the channel is available before trans- mitting a data packet or a'voice message. The chan- nel is available if either oftwo conditions is true.

1. Idle Status Symbol is detected. In this case, the MR's receiver is listening to a repeater system's outbound channel and the repeater has signaled that the inbound channel is idle.

2. No channel activity is detected. In this case, the MR's receiver is unable to hear any activity on the radio channel.

  The process used by the MR to determine if access to the inbound channel is allowed is illus- trated by the state diagram below. The MR should always assume that the inbound channel status is Unknown until it has determined otherwise.

TRANSUISSION COMPLETE/

SYNCHRONIZE To CHANNEL

FSSP TIME-OUT/ ASSUME CHANNEL

NEW PACKET TO TRANSMIT

L DELAY RANDOY TIME

FSSP TIME-OUT/

ASSULI;D;;ANNEL

1 FRAME """- '

CHANNEL IDLE/ DELAY OVER TRANSMIT FRAME WAIT FOR END 0 f SLOT

CHANNEL UNKNOWN WAIT FOR NEXT YICR SLOT

6,

Fig. 1

0 Motorola. Inc. 1995 6

November 1995

Ii

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MO7VROLA Technical Developments

8

MOBILE RADIO (MR) CHANNEL

ACCESSPROCEDURE

  MR transmit procedures are implemented to organize inbound transmissions in a manner which expedites the completion of data/voice communica- tions transactions in progress and reduces the poten- tial for collisions between contending MRS. These procedures are described below, with reference to Figure 1.

1. While the MR is in the RECEIVE-IDLE state and it has nothing to transmit, it shall respond to the arrival of a FRAME SYNC pattern by going to the RECEIVE SYNC state. In the RECEIVE FRAME SYNC state the receiver shall decode the NID and header block of each packet in order to recognize the NAC and its own address. After receiving any messages, if there are no further Frame Sync patterns then the receiver shall go to the RECEIVE IDLE state. Generally, an idle receiver will oscillate between these two st...