Abstract: An access contention scheme having both multi-level priorities and a contention-free access indicator for use by a station in a network of stations. When a contention control indicator is detected for a contention period, a station having a frame to transmit determines from the contention control indicator if it is permitted to contend for access to the transmission medium during the contention period. The station determines if the contention control indicator indicates a contention-free access and, if the contention control information indicates a contention-free access, the station determines if a channel access priority level associated with the frame to be transmitted is higher than a channel access priority level associated with a last transmitted frame.

Abstract: A rate-adaptive mechanism for optimizing transmitter/receiver connections on a carrier-by-carrier basis for maximum date rate based on channel attributes for that connection and direction. Channel information is produced by a channel adaptation process based on channel characteristics and is stored in both transmitter and receiver as a channel map with an associated a channel map index for channel map look-up. The channel map index for a channel map used to modulate a payload of a frame is conveyed by transmitter to receiver in the frame so that the receiver is able to select the correct channel map for demodulation.

Abstract: A method of operating in a network in which a plurality of stations communicate over a shared medium. The method comprises transmitting a group of bits from a transmitting station to a receiving station, wherein the group of bits comprises information bits and error checking bits, and communicating additional bits from the transmitting station to the receiving station without transmitting the additional bits. Communicating the additional bits comprises, at the transmitting station, deriving the error checking bits from the additional bits using an error checking process; and at the receiving station, using the same or a related error checking process to process candidate bits known to the receiving station, and comparing the output of the error checking process to the error checking bits received from the transmitting station to determine if the candidate bits correspond to the additional bits.

Abstract: A frame forwarding scheme for network stations operating in a shared medium data transmissions network. The frame forwarding scheme uses payload encapsulating delimiters and control information in the payload to enable a frame originating from a first station and intended for a second station to be forwarded to the second station by an intermediate station. The first station selects a station as an intermediate station for purposes of frame forwarding based on the data transmission quality or reliability to be achieved using that station as an intermediate station.

Abstract: A scheme for bounding latency of transmissions for QoS in network stations operating in shared medium access network. The length of segment burst transmissions are limited by allowing the segment burst transmission of a given priority to be interrupted by higher priority traffic. Restrictions are placed on frame length for transmissions of all priority levels or, alternatively, at all but the highest of the priority levels.

Abstract: A CSMA Media Access Control (MAC) scheme for supporting both centralized and distributed shared medium access control in a CSMA network. A master device exchanges connection control messages with a slave during using contention-oriented access to establish a connection and a session of periodic contention-free intervals. Once the session is established, the contention-free intervals alternate with contention-oriented intervals according to the timing parameters specified by the connection control messages.

Abstract: A robust Media Access Control (MAC) scheme for network stations operating in an OFDM transmissions network. The MAC scheme uses robustly transmitted frame control information to ensure network synchronization (for media access) and convey channel access prioritization for QoS. Frame control information can occur in a frame before and after the frame's payload, or in a response.

Abstract: A scheme for configuring an FEC encoder (including an associated interleaver) for changing data channel characteristics. Channel information specifying a modulation mode and carriers capable of supporting the modulation mode for the data channel is received by a transmitting network node for use in a data transmission to a receiving network node. The received channel information is based on a prior data transmission to the receiving network node over the data channel. Configuration values are computed from the received channel information and an amount of data to be transmitted in a data transmission. The FEC encoder is configured to operate on the data transmission data amount according to the configuration information.

Abstract: A partial ARQ protocol for multicast and broadcast transmissions in network devices operating in a shared medium access network. To support the partial ARQ, a media access control (MAC) protocol uses robustly transmitted frame delimiters and a MAC management frame structure. In a multicast or broadcast frame with partial ARQ, a destination address field is set to that of a selected proxy device's address, and the address of the intended recipients (of group address of the intended recipients) is placed in an entry in the MAC management frame structure. The frame also contains a multicast flag set to indicate that the transmission is intended for more than one device and a value in the frame delimiters to indicate that a response is requested. Upon receipt of such a frame, the proxy device specified by the destination address field provides an appropriate response type on behalf of the group.

Abstract: A scheme for identifying usable carriers for a particular modulation type and selecting, if possible, a modulation type for modulation of OFDM symbol block associated with data packets in a standard transmission mode based on data channel conditions. Channel estimation for an OFDM symbol block received by a receiving network node over a data channel during a packet transmission by a transmitting network node generates information indicative of noise events on symbols and carriers in the OFDM block, the generated information being related to modulation types available for the standard transmission mode, and determines from the generated information if at least one of the modulation types available for the standard transmission mode may be used for a next data transmission over the data channel by the transmitting network node using the standard transmission mode. One of the modulation types is selected if it is determined that at least one of the modulation types may be used.

Abstract: A scheme for configuring an FEC encoder (including an associated interleaver) for changing data channel characteristics. Channel information specifying a modulation mode and carriers capable of supporting the modulation mode for the data channel is received by a transmitting network node for use in a data transmission to a receiving network node. The received channel information is based on a prior data transmission to the receiving network node over the data channel. Configuration values are computed from the received channel information and an amount of data to be transmitted in a data transmission. The FEC encoder is configured to operate on the data transmission data amount according to the configuration information.

Abstract: An encoder/decoder scheme for robust transmission of PHY layer frame control information (to support medium access) in OFDM frames (or packets). The PHY layer frame control information to be modulated onto carriers in OFDM symbols is encoded using a product coding to form a product code block or matrix. The product coding is based on a shortened hamming code codeword set having properties of symmetry. Elements of the product code matrix are interleaved so that the elements are modulated onto the carriers of the symbols in diagonal groupings (across time and frequency) and with some degree of redundancy. The modulated elements are demodulated to produce soft decision values, which are de-interleaved to combine copies of the soft values for elements and re-order the soft values in the order of the elements prior to interleaving.

Abstract: An interleaving/de-interleaving scheme for providing redundancy with both time and frequency diversity to data in OFDM symbols in a data transmission system. On the transmit side, encoded data to be modulated onto carriers in OFDM symbols is interleaved by storing the encoded data in an interleaver memory and reading multiple copies of the encoded data from the interleaver memory so that the encoded data copies are spread in time on non-consecutive symbols and in frequency on non-adjacent carriers. On the receive side, the multiple copies of the OFDM data are received, and phase noise computations are used to combine the multiple copies (in either metric or phase angle form) into one. From the combined copies a single metric value to be used in decoding the OFDM data is produced.

Abstract: A windowing mechanism for processing an OFDM symbol is presented. The windowing mechanism applies an apodizing window function having the property Wj+W(FFTSize/2 +j)=constant, where FFTSize is the size of the FFT sample, to a received OFDM symbol sample and a time-offset version of the OFDM symbol sample to produce sets of windowed values. The time-offset sample is offset from the original symbol by one half the symbol period. The time-offset windowed sample is shifted into realignment with the windowed original symbol. Corresponding ones of the windowed values are summed together to restore the windowed symbol to its original form.

Abstract: A method is described for temporally aligning a received symbol that is transmitted via orthogonal channels, e.g., OFDM channels, with a reference symbol and/or an earlier received symbol. The method includes computing phases of the first symbol for the orthogonal transmission channels and comparing the computed phases of the first symbol with phases of the reference. The phases of the first symbol are successively displaced by a predetermined phase shift which depends on the channel frequency to obtain a correlation result. The temporal alignment is determined by detecting a correlation maximum based on the correlation result and used to synchronize the first symbol with the reference. The reference can also be an earlier received symbol to provide autocorrelation. The received symbols can be processed by applying a window function, e.g. a Hanning, Hamming or Blackman window.

Abstract: A mechanism for determining phases of a symbol for phase correlation is provided. The mechanism performs a symmetric apodizing window function on a symbol sample of a symbol having a symbol period of T and a time-offset symbol symbol sample offset from the symbol sample by T/2 to produce first windowed values for the symbol sample and second windowed values for the time-offset symbol sample. The mechanism applies a time shift to re-align the time-offset symbol sample with the symbol sample and sums the second windowed values and the corresponding first windowed values. The summed values are then converted to phases. The symmetric apodizing window function is an apodizing window function having the property W.sub.j +W.sub.(FFTSize,/2+j) =constant, where FFTSize is the size of the FFT sample. The symmetric apodizing window function, such as a Hanning window, may be performed in the time or frequency domain.

Abstract: An antenna dish structure is disclosed having a central support to which are attached a plurality of elongated ribs extending radially outwardly with a plurality of metallic mesh members extending between adjacent pairs of rib, and a rim structure connected to the outer ends of the ribs, with both the ribs and the rim having portions for receiving therewithin such mesh members.