Abstract: Disclosed are systems and methods which provide high bandwidth data communication with respect to a large coverage area using smart antenna and/or directional antenna (referred to herein as multi-beam antenna) technology. Circuitry may be provided at a WLAN AP to provide selection of particular antenna beams used in the downlink and/or uplink, control of multicast transmission, control of unicast transmission, and to provide antenna pattern shaping techniques. Embodiments implement multi-beam antenna technology with little or no hardware modifications to AP circuitry. Other embodiments implement multi-beam technology using radio front-end and/or radio hardware modifications to AP circuitry. Various diversity techniques may be implemented, such as selection diversity, maximum ratio combining, and equal gain combing. To provide desired antenna pattern shaping, phase offsets with respect to a signal as transmitted in each antenna beam may be employed.

Abstract: Some representative embodiments are directed to controlling access to a wireless medium using “credit” periods and “free” periods. During a credit period, credits are initially assigned to the stations and each station is repetitively polled as long as the station has credit remaining and data is available to communicate. During the free periods, stations are polled using a start-time fair queuing algorithm. By dividing the access to the wireless medium in this manner, real time applications may use the credit periods to prevent communication latency from deteriorating application performance. Specifically, the repetitive occurrence of the credit periods and the assignment of credits to the stations ensures that each station will communicate at least at a minimum data rate. Additionally, controlling access to the wireless medium in this manner prevents frame collisions and, thereby, increases network throughput.

Abstract: Disclosed are systems and methods which provide a busy tone or signal for use in communication collision avoidance in a wireless network, such as a WLAN, a cellular network, or other point-to-multipoint wireless network. An intelligent busy tone generator, upon the proper conditions, transmits a busy tone or signal to one or more wireless device which may otherwise be hidden from particular communications. According to embodiments the busy tone mimics a carrier sequence of an actual transmission to facilitate the wireless devices recognizing the channel as busy. Because the original uplink packet may be interfered by transmission of a busy tone carrier-sense sequence, embodiments are provided with interference cancellation capability. Interference cancellation circuitry of embodiments may operate in a plurality of modes, including a training mode (including an online training mode, an offline training mode, and a hybrid or combined mode) and an operating mode.

Abstract: Disclosed are systems and methods which provide high bandwidth data communication with respect to a large coverage area using smart antenna and/or directional antenna techniques. Embodiments provide extended wireless local area network (WLAN) coverage areas using a directional antenna, with the cooperation of a cellular system or proprietary WLAN infrastructure to perform best antenna beam pattern estimation and signaling. Stations disposed beyond a WLAN coverage area may establish contact and exchange signaling information with an access point through a secondary control channel. Such a secondary control channel signaling may be relatively low bandwidth and may be utilized to identify the need to communicate data, to identify a “best” directional antenna beam through which to communicate data, etcetera. Payload data may then be transmitted at a high bit rate through one or more smart antenna beams targeted at the appropriate stations.

Abstract: A distributed and adaptive method and system are provided for correcting routing errors due to packet deflections in a dual-shuffle exchange network (DSN). The DSN includes a shuffle-exchange network (SN) and an unshuffle-exchange network (USN). A packet that cannot be routed correctly will be temporarily "deflected" to a wrong route. This deflection, or routing error, is then registered and encoded in a routing tag of the header of the packet. Using this information, an error-correcting routing algorithm is then used to correct the error at a different part of the network. The method and system can be used either as the basis of a switch architecture of a ultra high-speed local-area network or metropolitan area network. Also, the method and system can be used in circuit switching. The DSN can achieve the Shannon's lower bound N log N on switch complexity with arbitrarily small packet-loss probability.

Abstract: Method and system for multicast routing in an ATM network including a multicast tree having a plurality of nodes interconnected by links wherein a weight representative of traffic congestion level is assigned to each link and at least one algorithm is utilized to find routes from a source node of the tree to multiple end nodes of the tree which minimize the sum-total of link weights. The method and system are disclosed with a 3-stage Clos switching network. One optimal and two heuristic algorithms are disclosed. The heuristic algorithms can find multicast routes that are close to optimal within a response time that is significantly lower than that of the optimal algorithm. A hybrid implementation in which the optimal and heuristic algorithms are run in parallel with a set time limit is also disclosed. Although the method and system are disclosed with the Clos switching network, the algorithms also apply to communications networks with a two-hop structure.