Abstract: As is reflected in the disclosed method and apparatus, the present invention is a technique to account for the variation in channel occupancy of a particular terminal or terminals during the call admission process. Instead, a channel utilization manager accounts for the probabilistic nature of the call admission decision by using a pre-determined, statistically justified value to represent the channel occupancy. The “per-call” channel occupancy value is determined by a number of factors, including the shared-communications channel data rate. Channel occupancy is incorporated into one or more cumulative distribution functions (CDF), which are evaluated by the channel utilization manager as part of the call admission process. In turn, each channel-occupancy CDF of a shared-communications channel can be generated from a CDF of the terminals' data rates on that channel, which data rates can be determined analytically or empirically.

Abstract: A method, apparatus and computer program product for coordinating adjacent channel transmissions on multiple-radio nodes is presented. A Maximum Channel Occupancy Duration (MCOD) limit for a length of an overall transmit period is defined. A set of timers (NNAV) for each neighbor node is maintained, each of said NNAV including a first timer (CTSNNAV) for the channel which, if set, indicates the maximum duration of a transmission to said neighbor node and a second timer (RTSNNAV) for a channel which, if set, prevents the neighbor node from authorizing a transmission the channel.

Abstract: A method, apparatus and computer program product for using a single-radio node and a multi-radio node in a wireless network having a control channel and at least one data channel is presented. One radio of the multi-radio node is kept tuned to the control channel. The single-radio node and the multi-radio node release the control channel at a predetermined time. Further, the data channels used by the single-radio nodes are released at the predetermined time. In such a manner single-radio and multi-radio nodes can co-exist harmoniously in wireless networks with increased bandwidth utilization and efficiency.

Abstract: A method and system reduce interference between overlapping first and second wireless LAN cells in a medium. Each cell includes a respective plurality of member stations and there is at least one overlapped station occupying both cells. An inter-cell contention-free period value is assigned to a first access point station in the first cell, associated with an accessing order in the medium for member stations in the first and second cells. The access point transmits a beacon packet containing the inter-cell contention-free period value, which is intercepted at the overlapped station. The overlapped station forwards the inter-cell contention-free period value to member stations in the second cell. A second access point in the second cell can then delay transmissions by member stations in the second cell until after the inter-cell contention-free period expires.

Abstract: Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering.

Abstract: Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering.

Abstract: A method and system for assigning downlink and uplink channels to a mobile station registered with a base station, which uses an interference-sensing scheme and which provides improved reliability and performance over conventional schemes.

Abstract: An access method for periodic contention-free sessions (PCFS) reduces interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations and an access point (AP) station. The access method for periodic contention-free sessions (PCFS) includes a fixed cycle time that reduces conflicts with PCFS from other cells. The PCFS from several cells are repeated in cycles of cycle period (CP), which is the contention-free period (CFP) of an access point times a factor that is a function of the number of overlapping cells. Periodic contention-free sessions (PCFSs) are generated, one from each overlapping cell. PCFS transmission attempts occur at the fixed specified time spacing following the start of the previous cycle. Each active AP sets a timer at CP and a PCFS is initiated when the timer expires. The timer is then reset to CP and this starts a new cycle.

Abstract: A method, apparatus and computer program product for transmitting broadcast/multicast data in a wireless network, is presented. The network includes either a plurality of multi-radio nodes, or a plurality of single-radio nodes, or a mix of multi-radio and single-radio nodes and the network further includes a control channel and at least one data channel. Transmission of the broadcast/multicast data occurs either on the control channel or on a data channel.

Abstract: Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering.

Abstract: Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering.

Abstract: A method, apparatus and computer program product for preventing occurrences of the hidden node problem are presented. A transmission request (CC-RTS) is received from a source node, the CC-RTS frame including a reservation duration value indicating the length of time needed for a transmission reservation. A timer is adjusted for the period other nodes must refrain from transmitting on the channel (NAV) equal to a duration of a transmission request/transmission response (CC-RTS/CC-CTS) handshake. When the CC-RTS has been denied, then a second CC-RTS frame is received having a reservation duration value of zero, and when the CC-RTS is accepted then the NAV is extended to remainder of the reservation duration value of the original CC-RTS frame. The CC-RTS and CC-CTS are sent at a more robust PHY mode than traffic frames.

Abstract: A method, apparatus and computer program product for avoiding exposed nodes in Wireless local Area Networks is presented. The method includes maintaining at a node a first timer (NAV_RTS) for a channel which, if set, prevents the node from authorizing a transmission on the channel to itself and maintaining at the node a second timer (NAV_CTS) for the channel which, if set, prevents the node from transmitting on the channel. The method further includes updating the NAV_RTS when a transmission request (CC-RTS) frame is received having a reservation duration value greater than zero and greater than a current value of the NAV_RTS, and updating the NAV_CTS when a transmission response (CC-CTS) frame is received having a reservation duration value greater than zero and greater than a current value of the NAV_CTS.

Abstract: An apparatus and method for polling stations that transmit periodic traffic streams are disclosed. A station transmits a polling request that specifies the temporal period of the station's traffic stream, and a coordinator, after receiving the polling request, repeatedly sends polls to the station in a rapid-fire manner until a response from the station is received. The coordinator estimates the temporal offset for the temporal period based on one or both of (i) the time at which the coordinator received the response, and (ii) the time at which the coordinator transmitted the particular poll to which the station responded. Based on the temporal period and temporal offset, the coordinator establishes a polling schedule that polls the station soon after the station generates a frame. The coordinator also monitors downlink traffic to polled stations and, when the downlink traffic is periodic, establishes a downlink transmission schedule accordingly.

Abstract: A method and system reduce interference between overlapping first and second wireless LAN cells in a medium. Each cell includes a respective plurality of member stations and there is at least one overlapped station occupying both cells. An inter-cell contention-free period value is assigned to a first access point station in the first cell, associated with an accessing order in the medium for member stations in the first and second cells. The access point transmits a beacon packet containing the inter-cell contention-free period value, which is intercepted at the overlapped station. The overlapped station forwards the inter-cell contention-free period value to member stations in the second cell. A second access point in the second cell can then delay transmissions by member stations in the second cell until after the inter-cell contention-free period expires.

Abstract: Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering.

Abstract: A method and an apparatus are disclosed that enable call admission control for telecommunications terminals that use shared-access resources, without relying on an implementation at every access point to provide those resources. In particular, in accordance with the illustrative embodiment of the present invention, a first wireless terminal calls a second terminal by transmitting a traffic stream description that specifies the nature of the call to an intermediary call-handling server, such as a Session Initiation Protocol (SIP) proxy server. The SIP proxy determines from the Internet Protocol address of the calling terminal that the terminal uses a shared-access resource—in this case, a wireless shared-communications channel—and makes a request to a channel utilization manager to admit the call. Subsequently, the SIP proxy receives a message from the channel utilization manager that indicates whether the call has been admitted.

Abstract: A method and an apparatus are disclosed that enable call admission control during a handover for a telecommunications terminal that uses a shared-access resource. In accordance with the illustrative embodiment of the present invention, a first wireless terminal and a second terminal are already on a call, and are exchanging traffic streams. As the wireless terminal moves out the current access point's coverage area and into a new access point's coverage area, the terminal disassociates with the current shared-communications channel and associates with the new channel. A channel utilization manager determines, based on (i) pre-existing data-transmission requirements and (ii) the physical layer rate of the new shared-communications channel, whether the amount that is currently available of a communications resource on the new channel, such as bandwidth utilization, is sufficient to support the call. The manager then notifies the call-handling server as to whether the existing call is accepted or rejected.

Abstract: Using low PF values in conjunction with traffic-adapted contention windows leads to substantial decreases in delay and jitter. In general, adaptation to traffic reduces contention or delay: opening up the contention window in congestion and closing it on relief. Residual backoff adaptation provides for the reduction of the already decremented backoff values of stations that interrupted the backoff countdown process due to a transmission. It is good to adapt both the contention window and the residual backoff in order to avoid jitter. Otherwise, if the contention window is reduced but residual backoffs stay unchanged, new arrivals will enjoy shorter backoff delays than older ones, resulting in greater jitter. Adjusting both preserves the relative ordering of backoff counter values, which implies also some form of age ordering. Different adjustments can be applied to different priority traffic.

Abstract: Using low PF values in conjunction with traffic-adapted contention windows leads to substantial decreases in delay and jitter. In general, adaptation to traffic reduces contention or delay: opening up the contention window in congestion and closing it on relief. Residual backoff adaptation provides for the reduction of the already decremented backoff values of stations that interrupted the backoff countdown process due to a transmission. It is good to adapt both the contention window and the residual backoff in order to avoid jitter. Otherwise, if the contention window is reduced but residual backoffs stay unchanged, new arrivals will enjoy shorter backoff delays than older ones, resulting in greater jitter. Adjusting both preserves the relative ordering of backoff counter values, which implies also some form of age ordering. Different adjustments can be applied to different priority traffic.