Agere Systems Inc.

Lucent Technologies Inc.

Ncr Corporation

Leo Monteban

Hendrik Moelard

Rienk Mud

Adriaan Kamerman

Hendrik Van Bokhorst

Wilhelmus J M Diepstraten

Wilhelmus Diepstraten

Richard M Van Leeuwen

Johannes P N Haagh

Gerrit Hiddink

Wilhelmus J Diepstraten

Harald Van Kampen

Loeke Brederveld

Albertus M G Claessen

Jan Hoogendoorn

Albert Eikelenboom

Wilhelmus JM Diepstraten

A medium-reservation mechanism improves transmission efficiency in a multiple-channel network that includes stations with limited-selectivity receivers. The mechanism employs a medium-request signal that conveys channel information. In this network, stations check the channel information in the medium-request signal to decide whether or not to comply with the medium-request signal. If the channel information identifies the channel that is close to the channel that the station is presently operating on, the station then complies with the medium-request signal. If the channel information identifies a channel other than the channel that the station is presently operating on, the station ignores the medium-request signal.

Medium reservation with channel selectivity

A method and apparatus are disclosed for reducing a transmission rate for retransmission of a current frame in a wireless communication system. The reduced transmission rate increases the probability that the current frame is correctly transmitted and acknowledged. The transmission rate is progressively reduced for the current frame to avoid the expiration of the frame's retry count, while not affecting the transmission rate of subsequent frames. The next frame should be transmitted at the highest rate permitted by the signal quality. A disclosed retry count expiry avoidance algorithm increases the reliability of a retransmission by lowering the transmission rate for the current frame when an acknowledgement is not received. When an acknowledgement is not received, the transmitting station proceeds to a retransmitting state where the transmitting station first attempts to retransmit the frame at the same rate. When the number of 'equal rate attempts' is exceeded, the retry count expiry avoidance algorithm enters to a fallback state, where the transmission rate is decreased in a progressive manner.

Method and apparatus for rate fallback in a wireless communication system

A power management method, in which creation of deliver opportunities for a wireless station (STA) of a WLAN system is managed using a designated sub-field of the frame control field in a MAC header. In one embodiment, the STA is adapted (i) to use the power management sub-field to communicate its power state to the access point (AP) and (ii) to run a periodicity timer, which starts when the STA has transitioned to the doze state. The STA transitions to the awake state either when it has a data frame available for transmission to the AP or when the periodicity timer runs out. In another embodiment, the AP and STA create deliver opportunities by entering a new mode of operation referred to as interactive traffic power management (ITPM) mode, during which the power management sub-field is ignored and the more data sub-field is used to communicate the power state and manage transitions of the STA between the awake and doze states. Embodiments of the invention improve WLAN system performance when the traffic load is such that data frames become available for transmission both at the STA and AP at relatively regular intervals, which is typically the case for interactive voice-over-WLAN applications.

Power management method for creating deliver opportunities in a wireless communication system

In the method of dynamically setting at least one threshold at an access point in a wireless local area network, signals from other access points are sensed, and a carrier detect threshold is determined based on the received signal strength of at least one of the sensed signals.

Method of dynamically setting at least one threshold at an access point in a wireless local area network and the access point

A wireless data communication system is operable in a power saving mode wherein stations are synchronized to be in an awake state to receive synchronizing messages (TIM, PSYNC) and traffic indicator information and are changed to a doze state if they are not to receive data messages. In one embodiment all stations () communicate via a base station access point (), which broadcasts synchronizing messages (TIM) at regular intervals identifying stations () that are to receive data messages. In another embodiment all stations () communicate directly with one another, one station assumes the role of a master station and broadcasts synchronizing messages (PSYNC), and stations () desiring to transmit data messages transmit traffic indicator messages (PTIM) to the appropriate destination stations (), in a synchronized awake period just before the next synchronizing message (PSYNC) is expected to arrive.

Wireless data communication system having power saving function

The present invention relates to a wireless local area network station comprising a signal processing element, a carrier detect sensing element, a defer behavior sensing element, and memory. The network station transmits and receives signals within a communication cell that defines a carrier detect zone and a defer zone around an access point. The network station associates with the access point by transmitting an association request to the access point and by receiving an association response from the access point during entry of the network station into the cell. The network station receives a preferred carrier detect threshold level value and a preferred defer behavior threshold level value from the access point and stores the carrier detect threshold and defer behavior threshold level values in its memory for use during operation while being associated with the access point.

Wireless LAN with carrier sense threshold adaption

A wireless data communication system is operable in a power saving mode wherein stations are synchronized to be in an awake state to receive synchronizing messages (TIM, PSYNC) and traffic indicator information and are changed to a doze state if they are not to receive data messages. In one embodiment all stations (,) communicate via a base station access point (,), which broadcasts synchronizing messages (TIM) at regular intervals identifying stations (,) that are to receive data messages. In another embodiment all stations (,) communicate directly with one another, one station assumes the role of a master station and broadcasts synchronizing messages (PSYNC), and stations (,) desiring to transmit data messages transmit traffic indicator messages (PTIM) to the appropriate destination stations (,), in a synchronized awake period just before the next synchronizing message (PSYNC) is expected to arrive.

A method and system of operating a wireless local area network station adapted to transmit and receive a signal within a communication cell. The method includes the steps of establishing a carrier detect threshold level, establishing a defer threshold level, and transmitting a signal when the signal level detected by the network station is above the defer threshold level. Additionally, the method further includes the step of receiving a signal transmission intended for the network station when the power of the received signal transmission is above the carrier detect threshold level.

Wireless local area network with enhanced carrier sense provision

For use with a wireless computer network having a plurality of access points, a mobile station adapted for communicating with the network via a current access point and having a scanning circuit for locating a new access point, the scanning circuit requiring a scanning period of time to locate the new access point, a method of operation of the mobile station and a wireless computer network infrastructure. The mobile station comprises: (1) a detection circuit that generates a ready-to-scan signal indicating that the mobile station is about to activate the scanning circuit and (2) a suspension circuit, coupled to the detection circuit, that receives the ready-to-scan signal and generates, in response thereto, a data suspend signal for transmission to the current access point, the data suspend signal causing the current access point to suspend transmission of data to the mobile station, thereby preventing loss of the data during the scanning period.

System and method for providing seamless handover in a wireless computer

For use in a wireless computer network having a radio relay capable of transmitting messages, a system and method, operable with the radio relay, for selectively repeating a unicast message received from a source end-station only upon some indication that a destination end-station has not received the message. The system includes: (1) a transceiver that receives the unicast message from the source end-station and (2) control circuitry, coupled to the transceiver, that determines whether the destination end-station has received the unicast message and causes the transceiver to refrain from repeating the unicast message if the destination end-station has received the unicast message, the radio relay thereby freed from repeating already-received unicast messages.

Wireless relay with selective message repeat and method of operation

A local area network system (10) includes a wired backbone LAN (12) having a plurality of LAN segments (14, 16, 18) interconnected by transparent bridges (26, 44). A plurality of base stations (22, 52) are capable, of communicating with a mobile wireless station (30). In response to a decision at the mobile wireless station (30) to switch communication from a first base station (22) to a second base station (52) a handover request message (172) is transmitted from the mobile wireless station (30) via the backbone LAN (12) to the first base station (22) thereby updating dynamic filtering databases contained in the base stations (22, 52) and transparent bridges (26, 44) through which the handover request message (172) passes as to the new communication location of the mobile wireless station (30).

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Nieuwegein, Netherlands

Leo Monteban