摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A power management method, in which duration 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. Either the STA or the access point (AP) can terminate the deliver opportunity, e.g., based on the amount traffic. In one embodiment, the STA is adapted (i) to use the power management sub-field to communicate its power state to the AP and (ii) to run a maximum-wait timer, which starts when the AP is informed that the STA is in the awake state. The STA transitions to the doze state either when it has received a data frame from the AP or when the maximum-wait timer runs out. In another embodiment, the AP and STA manage deliver opportunities by entering a new mode of operation referred to as interactive traffic power management (ITPM) mode. During this mode the power management sub-field is ignored and the more data sub-field is used to communicate the availability of data and to 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.
摘要:
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.
摘要:
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.
摘要:
A method and apparatus are provided for automatic data rate control in wireless communication systems, such as wireless LANs. A data rate controller adapts a transmission rate of said data based on a signal quality and a transmit power level. The data rate controller can also adapt the transmission rate based on one or more of amplifier non-linearities, anticipated signal quality for a next frame transmission, regulatory emission limits and data rate advice. The data rate advice will decrease a data rate if a current signal quality is below a minimum required signal quality for a given data rate and increase a data rate if a current signal quality is above a minimum required signal quality for a given data rate. A probation mechanism allows a higher rate to be evaluated before switching to the higher rate permanently. A retry balance mechanism forces a rate fallback when a number of failed transmission exceeds a predefined threshold. A rate fallback feature reduces the transmission rate when a number of failed transmission exceeds a predefined threshold.
摘要:
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.
摘要:
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).