Browse Prior Art Database

OPTIMAL BUFFER MAP FOR A TDMA HANDOFF

IP.com Disclosure Number: IPCOM000006585D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2002-Jan-16
Document File: 3 page(s) / 149K

Publishing Venue

Motorola

Related People

Charles John Malek: AUTHOR [+2]

Abstract

This invention refers to an inter-base handoff in a DECT (Digital European Cordless Telephone) personal cordless telephone system. The DECT protocol specifies a Time Division Multiple Access (TDMA) format.

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Page 1 of 3

MOTOROLA INC. Technical Developments Volume 16 August 1992

OPTIMAL BUFFER MAP FOR A TDMA HANDOFF

by Charles John Malek and Gregory I? Speck

  This invention refers to an inter-base handoff in a DECT (Digital European Cordless Telephone) personal cordless telephone system. The DECT protocol specifies a Time Division Multiple Access (TDMA) format.

  As a handset moves from a base with a poor receiver signal strength indication (RSSI), it scans neighboring cells on other time slots and frequencies, seeking a recep- tor base with an improved BER or RSSI. A portion of the DECT bit-stream protocol, depicting the physical and lower MAC layers, looks like this:

duplex (TDD) is used. TDD and TDMA together con- stitute a necessary and sufficient set for this invention.

  Now, a base can handle multiple time-slots simultane- ously. The architecture interconnect diagram (AID) of the base would look like this:

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  Notice in the above illustration that a single speech channel occupies l/12 of the available time slots. The B field contains user information, voice in our case. The A tield contains call signalling. Additionally, notice that as in many cordless telephony protocols, time-division

0 Motorola. Inc. 1992 161

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Page 2 of 3

MOTOROLA INC. Technical Developments Volume 16 August 1992

  A handset would be primarily composed of an RF deck, a microprocessor, and the same I.C. devoted to the physical layer and a portion of the MAC layer of the DECT protocol specification as shown here:

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  Now, it is the objective of this publication to show an optimum memory arrangement, minimizing silicon real-estate, particularly in the handset, where economies of scale are most beneficial.

  To maintain an active call (via the DECT protocol) requires a handset to transmit and receive an A-Field (call signaling) and B-Field (voice). An optimal buffer

map to implement one call would have 2 A-Field buffers and 2 B-Field buffers.

  If a handset is required to search for a more attrac- tive base (RFP), it must monitor an extra A-Field. This requires one more A-Field Buffers (total now: 3 A-Field buffers and 2 B-Field buffers).

  A typical handset, to handoff between two RFPs, would require the equivalent capacity of two ongoing calls. This adds 2 A-Field buffers and 2 B-Field buffers (total now: 4 A-Field buffers and 4 B-Field buffers).

  This invention reduces a typical solution by 2 B-Field buffers. First, this inv...