At&t Bell Laboratories

Kelvin K Ho

Douglas A Spencer

Charles Y Farwell

Richard M Heidebrecht

Michel L Hearn

Kenneth Wayne Strom

John S Thompson

Kenneth Frank Smolik

Alan S Mulberg

Brian D Bolliger

Talmage P Bursh, Jr

LaJeana N Roberts

Richard Alan Windhausen

Richard D Miller

Paul E Miller

Kenneth Yiu-Kwong Ho

David M Kissel

Michael A Smith

Michael J English

Marc K Dennison

A CDMA cellular radio-telephone system (FIG. 2) comprises a packet-switched communications network (202, 207, 201) that interconnects cells (base stations; 202) with each other and with the public telephone network (100). A unique combination of a static addressing plan that uses a different LAPD DLCI (302 in FIG. 7) for each unidirectional virtual call path, direct cell (202)-to-cell and cell-to-call-processing unit (264 in FIG. 5) control information exchanges, and packet-switching techniques that permit call traffic and control communications to share call paths and permit different call paths to share physical resources, is applied to call processing. This enables soft handoffs (FIGS. 27-29) to be handled in a manner transparent to the parties to the call and without significant involvement of system control elements (134 and 261 in FIG. 2) whose involvement would adversely impact the system's call-handling capacity. It also enables soft handoffs to occur without change of the call processing unit that is handling the call, so that a single call processing unit continues to handle the call from start to finish through even multiple soft handoffs.

Mobile telephone system call processing arrangement

A CDMA cellular radio-telephone system (FIG. 2) has switching systems (201) synchronized to public telephone network (100) timing signals (600), and radio telephones (203) and cell base stations (202) synchronized to a different clock (1000). Transmission delays between the cell base stations and the telephone network are variable. Switching systems include digital communications interfaces (264) to the telephone system, whose connections to the telephone system are synchronized to the telephone system, and whose connections to the cells are nominally also synchronized to the telephone system but whose processor (602) operates for each call within predefined windows (1302, 1402) of phase relationships to the operation of the cell that is handling the call, and occasionally adjusts (FIGS. 13-16) its phase relationships to the operation of the telephone system to achieve and maintain its operation within the predefined windows. Packet-switched communications (350) between the cells and the switching systems absorb the phase relationship fluctuations and the timing adjustments in inter-packet intervals. Circuit-switched signal communications between the switching systems and the telephone system absorb the timing adjustments by means of vocoder (604)-implemented slips--bit insertions or deletions--in the communications traffic bit stream.

Adaptive synchronization arrangement

A wireless-access communications system, such as a CDMA cellular radio-telephone system (FIG. 2), comprises a packet-switched communications network (202, 207, 201) that interconnects cells (base stations; 202) with each other and with the public telephone network (100). Traffic of individual calls is packetized, and packet-bearing frames (300 in FIG. 7) of a plurality of calls are then statistically multiplexed and frame-relayed through the network to yield the high capacity, efficiency, and speed of traffic transport and handoff required for a CDMA cellular system. At each call processing unit (264 in FIG. 5), individual calls are handled by individual service circuits (602 and 612) which perform speech-processing functions such as coding and decoding, tone insertion, and echo cancellation, and packet-to-circuit-switched-PCM traffic conversion. Processors (602) adapt call processing unit timing to compensate for asynchrony between cells and call processing units and variations in call path transmission delays. Cell-to-cell communications, fixed call path addressing, and packetized control message transfers ensure that the same service circuit handles a call through even multiple soft handoffs (FIGS. 27-29) and efficiently communicates simultaneously with all cells involved in the handoff without involvement of system control entities and negative effect on system call-handling capacity. Both coded (packet-switched) and uncoded (circuit-switched) radio-telephone traffic are accommodated side-by-side. Wherever possible, existing and proven technology and component units are used to achieve low cost and high reliability.

Wireless access telephone-to-telephone network interface architecture

A CDMA cellular radio-telephone system (FIG. 2) has switching systems (201) synchronized to public telephone network (100) timing signals (600), and radio telephones (203) and cell base stations (202) synchronized to different clock (1000). Transmission delays between the cell base stations and the telephone network are variable. Switching systems include digital communications interfaces (264) to the telephone system, whose connections to the telephone system are synchronized to the telephone system, and whose connections to the cells are nominally also synchronized to the telephone system but whose processor (602) operates for each call within predefined windows (1302, 1402) of phase relationships to the operation of the cell that is handling the call, and occasionally adjusts (FIGS. 13-16) its phase relationships to the operation of the telephone system to achieve and maintain its operation within the predefined windows. Packet-switched communications (350) between the cells and the switching systems absorb the phase relationship fluctuations and the timing adjustments in inter-packet intervals. Circuit-switched digital communications between the switching systems and the telephone system absorb the timing adjustments by means of vocoder (604)-implemented slips--bit insertions or deletions--in the communications traffic bit stream.

Growing community of inventors

Somerset, NJ, United States of America

Kelvin K Ho