Nortel Networks Corporation

Apple Inc.

Yoon Chae Cheong

Shalini Suresh Periyalwar

Bassam M Hashem

Nimal Gamini Senarath

Hang Zhang

Mark Earnshaw

Gamini Senarath

Robert Matyas

Mo-Han Fong

David G Steer

Koon Hoo Teo

Wei Huang

A method and apparatus for reducing signal interference within a cellular radio system to increase both coverage and capacity. The method and apparatus include altering the direction of beams within cell sectors is among discrete angular positions according to a predetermined, cyclic pattern. The predetermined, cyclic pattern varies in a group of adjacent cell sectors such that inter-cell interference is significantly reduced or eliminated by rotating at a different cycle the beams in adjacent cells. This discrete, angular movement of beams provides for downlink transmissions to be timed in such a way (i.e., scheduled) such that transmission to a user will occur in accordance with the beam and time slot having the best carrier to interference (C/I) ratio for that user.

Beam wobbling for increased downlink coverage and capacity

A method and apparatus are provided for selecting an optimum base station for communicating with a terminal in a wireless communication system. A base station controller stores two candidate sets for each terminal within communication range of the base stations controlled by the base station controller. One candidate set lists base stations for which the channel quality of the uplink channel between the base station and the terminal is acceptable for communication. The other candidate set lists base stations for which the channel quality of the downlink channel between is acceptable for communication. This allows the base station controller to take into account the predominant direction of traffic when assigning base stations for communication with the terminal.

Packet communication system with dual candidate sets for independent management of uplink and downlink transmissions

The present invention keeps track of channel change indicia associated with wireless communications with mobile terminals, and bases the scheduling of data in time slots of a scheduling period on the channel change indicia. The channel change indicia may be derived from any information that bears on the rate at which channel conditions are likely to change, such as the velocity the mobile terminals are traveling or actual channel condition measurements. Preferably, mobile terminals associated with intermediate values for the channel change indicia are given priority, and thus, scheduled for transmission before those with lower and higher values. The invention is applicable to uplink and downlink communications, and is particularly beneficial when implemented in uplink and downlink schedulers in a base station.

Scheduling based on channel change indicia

The present invention provides a fast and efficient retransmission technique, which allows a link control layer to request retransmission of frames upon receiving information from an underlying physical layer that an unsuccessful attempt to transmit data was detected. In general, a failed attempt to transmit a frame is detected at a physical layer of a receiver. In response, the physical layer of the receiver sends a message to a link control layer of the receiver to indicate the failed attempt to transmit a frame was detected. Upon receipt of the message, the link control layer sends a retransmission message to a corresponding link control layer of a sender. The retransmission message is configured to cause the sender to retransmit the unrecoverable data associated with the corrupted frame.

Physical layer assisted retransmission

The present invention provides cyclic power changing patterns for transmissions in different sectors of a cellular system. The cyclic power changing patterns define unique patterns in which transmission power levels change over a period of time slots or within a group of sub-carriers. Each sector has a unique pattern, so that interference information monitored by the user elements, which are supported by base stations, are indicative of the interference contributions from adjacent sectors. Based on these interference contributions and the cyclic power changing patterns associated with these sectors, the base stations can schedule transmissions to the user elements during time slots or in sub-carriers to minimize the impact of interference from the adjacent sectors and to efficiently support dynamic needs of the individual user data packets according to QoS requirements.

Cyclic transmit power adjustment scheme

A wireless communication system () includes a network (), one or more mobile stations (), and a medium access control (MAC) protocol (). The MAC protocol () includes a state transition design () and a control channel design (). The state transition design () includes null (), dormant (), standby (), and active states () for each mobile station (). The control channel design () includes a common control channel (), a slow control channel () and a fast control channel (), and is adapted to control communications from the network to each mobile station.

Medium access control (MAC) protocol for a wireless communication system

The present invention provides an access point, such as a base station, facilitating wireless communications with a plurality of mobile terminals, which are capable of operating in an active or standby mode. The access point provides active-to-standby transition timers for controlling when to instruct active mobile terminals to enter a standby mode after the end of a communication session. The active-to-standby transition timers have variable values based on one or more Quality of Service (QoS) parameters. Different mobile terminals may be associated with different QoS levels. The values for the active-to-standby transition timers may vary based on their respective QoS levels. The initial values for the active-to-standby transition timers may differ depending on the QoS level for the associated mobile terminal. As the QoS parameters indicate conditions adversely affecting QoS, the active-to-standby timer values may decrease in proportion to the QoS parameters.

Adaptive state transition control

A method and apparatus are provided for error correction in a communication system employing Orthogonal Frequency Division Multiplexing. When a remote unit receives an OFDM symbol, a retransmission indicator bit is examined to determine whether the symbol is an original symbol or a retransmitted symbol. If it is a retransmitted symbol and the remote unit has a corresponding symbol stored in memory, then the received symbol is soft-combined with the stored symbol. Each packet in the symbol, either the received symbol if original or the soft-combined symbol if retransmitted, is examined by the remote unit. If the remote unit determines that a particular packet is intended for the remote unit, but can not determine the contents of the payload of the packet, the remote unit sends a retransmission request to the base station for retransmission of the symbol. The base station determines whether the entire symbol or merely the packet should be retransmitted, based on such considerations as the size of the packet or whether there are additional requests for the symbol. The invention allows both soft-symbol combining and Automatic Repeat Request to be used as error correction techniques.

Enhanced ARQ with OFDM modulation symbols

A multi-hop relaying method and apparatus used in a cellular network. The multi-hop transmission scheme utilizes intelligent relays within a conventional cellular system having at least one base station, one or more intelligent relays, and user equipment elements. The method includes selecting the strongest pilot signal from among the base stations and intelligent relays, reporting such to the base station, distributing an active user list to the relays along with scheduling and routing information via a relay control channel, and transmitting data according to a respective active user based upon the pilot signal strength to maximize coverage and capacity over the cellular system.

Multi-hop intelligent relaying method and apparatus for use in a frequency division duplexing based wireless access network

A radio link protocol for a communications system ensures that delivery of Internet protocol data packets occurs within a set delay bound for the packets, in order to satisfy specified quality of service levels. Data packets arriving at a transmitter are subdivided into data blocks. As each block is transmitted, the transmitter starts an associated acknowledgement timer. The timer is turned off, before it expires, if the transmitter timely receives from a receiver a message informing the transmitter that the associated block was successfully received. If such message is not received, the timer expires and the transmitter sends an acknowledgement request signal to the receiver and starts an associated panic timer. The panic timer is turned off, before it expires, if the transmitter subsequently timely receives a message that the associated block was successfully received. If such message not received, the panic timer expires and the transmitter sends one of more copies of the corresponding block to the receiver before occurrence of the delay bound. If the transmitter receives a negative acknowledgement message from the receiver, that a block is missing or corrupted, the transmitter retransmits a copy of the block to the receiver. To reduce messaging traffic, the transmitter cancels acknowledgement and panic timers based upon information contained in negative acknowledgement messages, and the receiver can periodically send acknowledgement messages to inform the transmitter of successfully received blocks.

Method and apparatus for transmitting data over a network within a specified time limit

Methods, receivers and transmitters all adapted to assist in the performance of layer 2 frame delineation are provided which are applicable in the context of OFDM, and also applicable to any layer 1 design facilitating high data rate transmission. Advantageously, the invention allows the identification of where a layer 2 frame begins notwithstanding the fact that the previous layer 2 header, which would normally be used to identify the location of the next layer 2 frame, has been received in error. As a consequence, rather than discarding considerable quantities of data after an erroneous header, for example all data until a super-frame boundary, layer 2 frames can be correctly received staring with the next header received in a non-erroneous layer 1 frame.

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Kanata, Canada

Yoon Chae Cheong