Abstract: An error management system and process can be used to identify an erroneous data packet in a data stream. In response to identifying the erroneous data packet, a subsequent valid data packet is located in the data stream. In one embodiment, a plurality of candidate locations of header checksum windows are searched and checked for a valid checksum. Multiple integrity checks of multiple header checksums can be used to reduce the probability of a false positive integrity check. In another embodiment, one or more information data fields can used for determining packet integrity by determining if the fields contain valid information bits.

Abstract: An apparatus, system and method for converting data in a first packet format, having overhead data in the form of headers and/or trailer padding, into a second, variable-length packet format, in which some of the header and/or trailer overhead is removed during conversion in order to more efficiently utilize the limited bit rate capacity of a link which will convey the data in the second format. Embodiments include a communication subnetwork for interconnecting a plurality of users to a wide area network through a wireless link, an Asynchronous Transfer Mode (ATM) switch for converting ATM cells into a variable-length packet format, and a convergence system for converting ATM cells into data packets in Media Access Control (MAC) format.

Abstract: An extended wireless communication system allows a subscriber station which has an unacceptable (weak or inoperative) wireless link to a base transmitter station to communicate with the network via a wire connection to a second subscriber station which has a strong wireless link to the network. A first subscriber station which has an unacceptable first wireless link to a base station of the network uses a second wireless subscriber station which has a strong or acceptable second wireless link to the local base station to relay data back and forth between the first subscriber station and the network. The first and second stations are configured to send data to and from the first station via the second wireless link, the second station, and an existing wire connection between the first and second subscriber stations.

Abstract: The invention relates to communication systems and to systems and methods for implementing adaptive call control in such systems. Adaptive call control can determine what CPE to base station calls (connections) are allowed at any given time. Call control, coupled with precedence, can further determine what connections are suspended if less bandwidth is available than is currently committed. Multiple techniques are disclosed to select connections for suspension. These techniques include suspending enough connections through the affected CPE until there is enough bandwidth to meet the remaining commitment, randomly (or in a round robin fashion) choosing connection to suspend from the entire set of connection, and using precedence priority levels.

Abstract: A system and method for mapping a combined frequency division duplexing (FDD) Time Division Multiplexing (TDM)/Time Division Multiple Access (TDMA) downlink subframe for use with half-duplex and full-duplex terminals in a communication system. Embodiments of the downlink subframe vary Forward Error Correction (FEC) types for a given modulation scheme as well as support the implementation of a smart antennae at a base station in the communication system. Embodiments of the system are also used in a TDD communication system to support the implementation of smart antennae. A scheduling algorithm allows TDM and TDMA portions of a downlink to efficiently co-exist in the same downlink subframe and simultaneously support full and half-duplex terminals. The algorithm further allows the TDM of multiple terminals in a TDMA burst to minimize the number of map entries in a downlink map.

Abstract: Base stations having potentially interfering terminal stations that are geographically located on the same or similar diagonal or Line of Sight (relative to the base station) operate on a first set of time frames (e.g., “even” time frames). Similarly, base stations having potentially interfering terminal stations that are not geographically located on the same or similar diagonals operate on a second set of time frames (e.g., “odd” time frames). By alternating in their use of the even and odd frames, the potential for co-channel interference between terminal stations is minimized. Systems and methods are disclosed which reduce co-channel and adjacent channel interference between terminal stations of different cells as well as adjacent channel interference between terminal stations of adjacent cells. The methods and systems so described can be used during the deployment or expansion of a communication system in a region.

Abstract: A system that provides a wireless broadband connection between base stations and customer sites is described. The system includes indoor units within the base stations and customer sites and communicate across cables to outdoor units. The indoor units link to routers, switches and other devices and services. The outdoor units transmit and receive wireless data and send it to the indoor units. The indoor units can store software instructions in the outdoor unit. This allows the indoor units to automatically detect problems with outdoor unit and download new software to them in case of an error.

Abstract: The invention relates to communication systems and to systems and methods for implementing adaptive call admission control (CAC) in such systems. Adaptive call admission control can determine what CPE to base station calls (connections) are allowed at any given time. CAC, coupled with precedence, can further determine what connections are suspended if less bandwidth is available than is currently committed. Multiple techniques are disclosed to select connections for suspension. These techniques include suspending enough connections through the affected CPE until there is enough bandwidth to meet the remaining commitment, randomly (or in a round robin fashion) choosing connection to suspend from the entire set of connection, and using precedence priority levels.

Abstract: A method and apparatus for adaptively obtaining bandwidth requests in a broadband wireless communication system. The method and apparatus includes dynamically varying technique combinations enabling a plurality of users to efficiently request bandwidth from a shared base station. A user may “piggyback” a new bandwidth request upon, or set a “poll-me bit” within, presently allocated bandwidth. A base station may poll users, individually or in groups, by allocating unrequested bandwidth for new requests. Polling may respond to a “poll-me bit,” and/or it may be adaptively periodic at a rate based on communication status parameters, such as recent communication activity and connection QoS levels. Group polling permits a possibility of collisions. Polling policies may be established for dynamically varying user groups, or may be determined for each user. Dynamic selection of appropriate polling techniques makes use of efficiency benefits associated with each technique.

Abstract: A bandwidth efficient subscriber unit initialization and synchronization method and apparatus is described. The inventive subscriber unit initialization and synchronization method and apparatus uses a combination of an access burst format and a data transportation technique to efficiently use bandwidth when initializing and synchronizing subscriber units in a time-synchronized communication system. Advantageously, the present invention provides a mechanism for a base station to receive multiple access bursts from multiple subscriber units in a single contiguous time period. In the preferred embodiment of the present invention, bandwidth is efficiently utilized by searching for multiple initial access bursts from multiple mobile stations during a single time period known as a new access opportunity. The preferred embodiment of the present invention initializes and synchronizes subscriber units in a “contention-based” manner.

Abstract: A method and apparatus for requesting and allocating bandwidth in a broadband wireless communication system. The inventive method and apparatus includes a combination of techniques that allow a plurality of CPEs to communicate their bandwidth request messages to respective base stations. One technique includes a “polling” method whereby a base station polls CPEs individually or in groups and allocates bandwidth specifically for the purpose of allowing the CPEs to respond with bandwidth requests. The polling of the CPEs by the base station may be in response to a CPE setting a “poll-me bit” or, alternatively, it may be periodic. Another technique comprises “piggybacking” bandwidth requests on bandwidth already allocated to a CPE. In accordance with this technique, currently active CPEs request bandwidth using previously unused portions of uplink bandwidth that is already allocated to the CPE.

Abstract: An adaptive time division duplexing (ATDD) method and apparatus for duplexing transmissions on a communication link in wireless communication systems. Communication link efficiency is enhanced by dynamically adapting to the uplink and downlink bandwidth requirements of the communication channels. Time slots are flexibly and dynamically allocated for uplink or downlink transmissions depending upon the bandwidth needs of a channel. Communication link bandwidth requirements are continuously monitored using sets of pre-determined bandwidth requirement parameters. Communication channels are configured to have either symmetric or asymmetric uplink/downlink bandwidths depending upon the needs of the channel. Channel bandwidth asymmetry can be configured alternatively in favor of the uplink transmissions.(i.e., more time slots are allocated for uplink transmissions than for downlink transmissions) or in favor of the downlink transmissions (i.e.

Abstract: A method and apparatus for a self-correcting bandwidth request/grant protocol in a broadband wireless communication system is disclosed. The self-correcting bandwidth request/grant protocol utilizes a combination of incremental and aggregate bandwidth requests. In accordance with the present inventive protocol, CPEs primarily transmit incremental bandwidth requests to their associated base stations, followed by periodic transmissions of aggregate bandwidth requests. The use of incremental bandwidth requests reduces risks that a base station erroneously issues duplicate bandwidth allocations to the same CPE for the same connection. Race conditions that may have occurred using only aggregate bandwidth requests are eliminated by requiring the CPEs to request bandwidth in an incremental manner. However, use of periodic aggregate bandwidth requests (that express the current state of their respective connection queues) allows the present bandwidth allocation method and apparatus to be “self-correcting.

Abstract: A method of assigning downlink time slots to receive units where the units may generate data using different modulation schemes. The method preferably assigns the downlink time slots as a function of the complexity of modulation schemes employed by the units. Further, the method preferably assigns the time slots from the least complex modulation scheme to the most complex scheme. The method may further assign uplink time slots to transmit units where the transmit units may generate data using different modulation schemes. The method preferably assigns the uplink time slots as a function of the complexity of modulation schemes employed by the uplink units. Further, the method preferably assigns the uplink time slots from the least complex modulation scheme to the most complex scheme. In other embodiments, the downlink time slots are assigned as a function of the bit per symbol rate employed by the receive units, preferably from the lowest bit per symbol rate to the highest bit per symbol rate.

Abstract: A method and apparatus for a self-correcting bandwidth request/grant protocol in a broadband wireless communication system is disclosed. The self-correcting bandwidth request/grant protocol utilizes a combination of incremental and aggregate bandwidth requests. In accordance with the present inventive protocol, CPEs primarily transmit incremental bandwidth requests to their associated base stations, followed by periodic transmissions of aggregate bandwidth requests. The use of incremental bandwidth requests reduces risks that a base station erroneously issues duplicate bandwidth allocations to the same CPE for the same connection. Race conditions that may have occurred using only aggregate bandwidth requests are eliminated by requiring the CPEs to request bandwidth in an incremental manner. However, use of periodic aggregate bandwidth requests (that express the current state of their respective connection queues) allows the present bandwidth allocation method and apparatus to be “self-correcting”.

Abstract: The present invention is a novel method and apparatus for efficiently transporting and synchronizing data between the Media Access Control (MAC) and physical communication protocol layers in a wireless communication system. An inventive method and apparatus for transporting and synchronizing to fixed-length ATM cell boundaries and for protecting against the potential misinsertion of ATM cells has been described. An inventive ATM packet format is described. The ATM packet format is used by the present invention for the transportation and synchronization of ATM cells. The ATM packets include fields that are used to detect errors occurring within each ATM cell. ATM cells are transported in exactly two TC/PHY packets, or TDUs. ATM header information is contained in the first TDU only. No ATM header information is carried by the second TDU. An entire ATM cell is discarded if an uncorrectable error is detected in the first TDU. If no uncorrectable error occurs in the first TDU, the second TDU is checked for errors.

Abstract: A system that provides a wireless broadband connection between base stations and customer sites is described. The system includes indoor units within the base stations and customer sites and communicate across cables to outdoor units. The indoor units link to routers, switches and other devices and services. The outdoor units transmit and receive wireless data and send it to the indoor units. The indoor units control the timing of detector measurements in the outdoor unit by transmitting a regular, repeating control message at a predetermined time. Once the outdoor unit receives the control message, it samples its detectors and reports measurements back to the indoor unit.

Abstract: A method for allocating fractional bandwidth in a fixed-frame communication system is described. The method includes calculating the integral cells per frame required at a connection, calculating the fractional cells per second required at the connection, setting a counter, adding the fractional cells per second to the counter, determining if the counter is above a preset limit, allocating an additional cell when the counter exceeds the preset limit, and reducing the counter a predetermined amount to reflect allocating the cell.

Abstract: The present invention is a novel method and apparatus for efficiently transporting and synchronizing data between the Media Access Control (MAC) and physical communication protocol layers in a wireless communication system. Depending on the length of the MAC packet to be transported, the present invention either fragments or concatenates the MAC packet when mapping to the physical layer. When a MAC packet is too long to fit in one TC/PHY packet, the MAC packet is fragmented and the resultant multiple TC/PHY packets are preferably transmitted back-to-back within the same TDD frame. When a MAC packet is shorter than a TC/PHY packet, the next MAC packet is concatenated with the current MAC packet into a single TC/PHY packet unless an exception applies (e.g., a change in CPE on the uplink or a change in modulation on the downlink). When an exception applies, the next MAC packet is started on a new TC/PHY packet following either a CTG or MTG.

Abstract: On embodiment of the system and method provides asymmetric adaptive modulation which allows uplink and downlink subframes of data to be transmitted between a base station and a CPE with different modulation schemes, thus increasing the efficiency of downlink transmissions while maintaining the stability of uplink transmissions. In systems with multiple CPEs, each CPE and base station pair can independently select their uplink and downlink modulation techniques. The system and method are also adaptive in that they adjust the modulation schemes based on, for example, signal to noise ratio measurements or bit error rate measurements.