At&t Bell Laboratories

At+t Corp.

Lucent Technologies Inc.

Charles Y Farwell

Richard Alan Windhausen

Richard D Miller

Douglas A Spencer

Richard M Heidebrecht

Kelvin K Ho

Michel L Hearn

John S Thompson

Alan S Mulberg

Paul E Miller

David M Kissel

Michael A Smith

Michael J English

Kenneth Wayne Strom

Kenneth Frank Smolik

Kenneth Yiu-Kwong Ho

Talmage P Bursh, Jr

Brian D Bolliger

David Martin Sueper

LaJeana N Roberts

Michael L Hearn

Terry L Zrust

Hassan Hagirahm

Paul M Gerhardt

Marc K Dennison

In a multimedia communications system where bandwidth of an access facility is limited, the bandwidth is partitioned into three bands dedicated to audio, video and data traffic, respectively, in accordance with blocking probabilities associated with the respective media types. The value of each blocking probability is selected pursuant to the relative importance of the associated media type in a multimedia service. With the blocking probabilities in place, the dominance of traffic of a particular media type, which may be relatively unimportant in the service, would not cause blocking of traffic of other media types, which may be relatively important.

Technique for efficiently allocating bandwidth to multimedia calls in a

Base stations responding on a shared channel to a registration request message received on another shared channel from a wireless mobile unit with the base station to which the mobile unit is assigned transmitting in a first time slot and the other base stations transmitting in a time slot determined by the strength of the received signal from the mobile unit. If two base stations respond to the registration request message in the same time slot and the assigned base station does not respond, the mobile unit determines whether there is a response in a time slot which is earlier in time to the first time slot than the collided time slot. If the collided time slot is earlier in time than any other time slot in which a response is received, the mobile unit transmits a second registration request message specifying the collided time slot. Each of the base stations that had responded in the collided time slot responds by sending a base reply message in a random time slot, and the other base stations do not respond to this second registration request message. The mobile unit selects one of the base reply messages in a random time slot.

Prioritizing a multiple access channel in a wireless telephone system

An arrangement for effecting call handoffs in a wireless communications system (FIG. 1 ) in a substantially glitchless manner. The arrangement relies on the mobile terminal (4) that is involved in a handoff to trigger the handoff by transmitting a handoff coordination signal simultaneously to the base stations (1, 2) that are involved in the handoff. The base stations receive the signal substantially simultaneously, and in response the base station that has been serving the mobile terminal's call ceases to do so while the base station that is henceforth to serve the mobile terminal's call commences to do so at the same instant in time.

Mobile-synchronized handoff in a wireless communications system

Signaling a mobile unit to transmit a synchronization pattern with voice information upon detecting from the signal strength of the wireless mobile unit by a base station that the mobile unit is approaching a minimum threshold. Where the voice information is initially being transmitted in a set of frequency hopping channels using spread spectrum transmission, the synchronization pattern is transmitted in one or more of the set of frequency hopping channels. In addition, the base station alerts a system controller to this fact, and the system controller requests that neighboring base stations monitor the set of frequency hopping channels being transmitted by the mobile unit. In order to synchronize to the mobile unit, the base stations utilize the synchronization pattern to come into synchronization with the mobile unit. The system controller transfers the wireless mobile unit to the base station which is receiving the strongest signal strength.

Call handoff in a wireless telephone system

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 & 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 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.

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

Denver, CO, United States of America

Charles Y Farwell