Abstract: An apparatus and method for polling stations that transmit and receive periodic traffic streams are disclosed. The illustrative embodiment determines when to transmit a frame comprising a data payload and a poll to a station based on (i) the temporal period and temporal offset of the traffic stream transmitted by the station, and (ii) the temporal period and temporal offset of the traffic stream received by the station, such that delays for either the transmitted traffic stream or the received traffic stream are reduced. The present invention is particularly advantageous for latency-sensitive applications such as voice and video telecommunications.

Abstract: An apparatus and method for informing a coordinator of the particular characteristics of a periodic traffic source are disclosed. A station that generates a periodic traffic stream encodes the temporal period and temporal offset of the traffic stream within a quality-of-service (QoS) traffic specification, and transmits the traffic specification with a poll request. The coordinator, upon receiving a polling request, processes the associated traffic specification and, via appropriate decoding logic, determines whether the requesting station generates periodic traffic, and if so, the temporal period and temporal offset of the traffic stream. The coordinator subsequently can establish, based on the temporal period and temporal offset, a polling schedule that minimizes the delay between (i) the station generating a frame, and (ii) the station transmitting the frame (and thus the destination receiving the frame).

Abstract: A cyclic prioritized multiple access (CPMA) method is disclosed which includes Fixed Deterministic Post-Backoff. Fixed deterministic post-backoff reduces conflicts between access points of overlapping cells. Contention-free sessions (CFSs) can be generated, one from each overlapping cell. Each active access point engages in a fixed deterministic post-backoff. A fixed deterministic backoff delay (Bkoff times a fixed number of idle time slots) is used by all access points, with the value of Bkoff being greater than the number of overlapping cells. The Bkoff should be large enough to enable the traffic that needs to be accommodated by the channel. Each access point has a backoff timer that is counted down using the shortest interframe space possible, typically the Priority Interframe Space (PIFS). A contention-free session (CFS) is initiated when the backoff timer expires, and it is then reset to the value of Bkoff to start a new cycle.

Abstract: A method is disclosed for addressing the problem of uplink capture, which arises in a multiple-cell wireless LAN using directional antennas. The use of directional antennas may adversely impact the performance of channel access protocols. CSMA-type MAC protocols provide dynamic bandwidth allocation in a distributed manner, eliminating idle time intervals. With such protocols, time-overlapped uplink transmissions by stations illuminated by different beams cooperate to capture the channel for long time periods. Without special measures, an imbalance could arise in the opportunity for the AP to access the channel, which could result in downlink delay and jitter and overall capacity loss. According to this invention, the uplink capture problem is mitigated by requiring all (non-AP) stations to release the channel at pre-specified times.

Abstract: A staggered startup method and system for a cyclic prioritized multiple access (CPMA) system reduce interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations. A first member station in the first cell coordinates a periodic sequence of first contention-free sessions. Each contention-free session includes multiple bursts with other member stations in the first cell. The first member station retains control of the medium by using interframe spaces sufficiently short between the bursts so that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session. A second member station in the second cell listens to the activity in the medium and detects an end to one of the first contention-free sessions indicated by an interval longer than a PIFS idle interval following an end to the activity in the medium.

Abstract: Overlapped wireless LAN cells in a medium have an equal chance at establishing a session on the medium. A first member station in the first cell transmits a timing packet containing a timestamp value, which is received at a second member station in the second cell. This synchronizes member stations in the first and second cells to interrupt transmissions at a global channel release instant corresponding to the timestamp value. The member stations in the first and second cells then have the opportunity to contend for access to the medium following the global channel release instant, using a slotted CSMA/CA access method. Each of the member stations in the first and second cells has a superframe clock that is synchronized based on the timestamp value, thereby establishing a periodic global channel release instant during each of a plurality of periodic superframes. The member stations can then periodically interrupt transmissions at the periodic global channel release instant to contend for the medium.

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: An access point transmits a preemptive peg packet when it has no data to transmit in order to maintain the contiguity of its transmission timing position with respect to the timing position of other contention-free sessions (CFS) transmitted by other access points in an existing, periodic sequence. The cyclic prioritized multiple access (CPMA) method establishes the transmission timing position of contention-free sessions (CFS) between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations. If an access point has no traffic, it will transmit a short, preemptive pegging packet and reset its backoff timer. In this manner, no gaps longer than the distributed coordination function (DCF) Interframe Space (DIFS) are left idle. This prevents other stations from using DCF contention to seize the channel, until all access points have completed one contention-free session (CFS) per periodic cycle.

Abstract: A method and system are disclosed for coordinating RF use in primary and adjunct wireless systems which are overlapped or layered in a common geographic area and which share the same the same RF spectrum. The adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell. The primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell. The adjunct base stations monitor all RF channels and partition them into two sets, a set of channels likely to be interference-free and a set of noisy channels. Once control channels have been assigned to the base stations, the adjunct mobile stations may also participate in the monitoring step by employing the MAHO/MACA features of the IS 136 or GSM Air Interface Standard.

Abstract: A method and system reduce interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations. 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 in the first cell transmits an initial shield packet to deter other stations from contending for the medium. The access point then transmits a beacon packet containing 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: A method is disclosed for addressing the problem of neighborhood capture, which arises in a multiple-cell wireless LAN with fewer channels available than the number of cells. Channel selection in WLAN networks must be accompanied by dynamic bandwidth allocation in order to avoid interference between co-channel cells. CSMA-type MAC protocols provide dynamic bandwidth allocation in a distributed manner, obviating the need for a central controller. With such protocols, time-overlapped transmissions by stations in non-interfering co-channel cells cooperate to capture the channel for long time periods. The result is deleterious to QoS because of the ensuing access delays in other co-channel cells.

Abstract: Self RF engineering is made possible for a wireless communication system by adding to the self-configuration capability the ability to set autonomously the power levels of the system base stations. The same data is employed as in self configuration. A further improvement for systems using the IS 136 Air Interface Standard consists of the capability to collect the required data through the functionalities of the MAHO/MACA (Mobile Assisted Hand Off/Mobile Assisted Channel Assignment). Improved system-initialization procedures are presented.

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: 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: Self RF engineering is made possible for a wireless communication system by adding to the self-configuration capability the ability to set autonomously the power levels of the system base stations. The same data is employed as in self configuration. A further improvement for systems using the IS 136 Air Interface Standard consists of the capability to collect the required data through the functionalities of the MAHO/MACA (Mobile Assisted Hand Off/Mobile Assisted Channel Assignment). Improved system-initialization procedures are presented.

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: Self RF engineering is made possible for a wireless communication system by adding to the self-configuration capability the ability to set autonomously the power levels of the system base stations. The same data is employed as in self configuration. A further improvement for systems using the IS 136 Air Interface Standard consists of the capability to collect the required data through the functionalities of the MAHO/MACA (Mobile Assisted Hand Off/Mobile Assisted Channel Assignment). Improved system-initialization procedures are presented.

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: A method is disclosed for performing a distributed computation for RF Management in a wireless communications network. The computation involves a sequence of computation stages. The wireless network has a plurality of base stations, each base station contributing data the computation. Each base station engages in a respective stage of the distributed computation. The sequence in which the base stations are engaged in the computation, known as the “follower order”, is specified in advance and is known to all the base stations. The method includes the step of beginning a first stage of the computation at a first base station in the specified sequence and performing each of the plurality of computation stages by a respective nth one of the plurality of base stations, the nth base station having access to a corresponding data set x(n).

Abstract: Self RF engineering is made possible for a wireless communication system by adding to the self-configuration capability the ability to set autonomously the power levels of the system base stations. The same data is employed as in self configuration. A further improvement for systems using the IS 136 Air Interface Standard consists of the capability to collect the required data through the functionalities of the MAHO/MACA (Mobile Assisted Hand Off/Mobile Assisted Channel Assignment). Improved system-initialization procedures are presented.