摘要:
In a packet detector, one or more tests are performed for packet detection according to packet detection parameters associated with the one or more tests, a rate of false detection is measured, and the packet detection parameters are adjusted accordingly to reduce the rate of false detection. The rate of false detection might be determined by analyzing post-detection and processing of a signal deemed to be a signal representing a packet for a failure of decoding indicative of a false detection. Such analysis might include testing for a failed SFD search, training symbol anomalies, poor conditioning of metrics used to determine frequency offset and OFDM timing, incorrect data fields, or the like.
摘要:
A modified preamble is used by extended devices that operate in mixed mode environments and green field environments, to accommodate beamforming of transmissions. In one process, an extended wireless device processes data for transmission of that data as a packet, wherein the extended wireless device is a device configured to communicate using a standard protocol understood by each node device and an extended protocol not understood by legacy node devices. If the packet is to be directed at an extended device, the extended wireless device sends a preamble of that packet that is usable in an extended mode at extended devices and usable at a receiving legacy device to determine that the receiving legacy device is not the destination of data to follow the preamble. Once the receiving legacy device is expected to be deferring the network, the extended wireless device can beamform its signal or otherwise vary from the legacy protocol in communications with extended devices.
摘要:
To detect the number of transmit antennas, a fast Fourier transform operation is performed on the received samples of the transmitted long training symbols of a preamble. Next, each of the Fourier transformed results is multiplied with the reference frequency-domain representation of the long training symbol so as to remove the effect of the symbols and to maintain the channel information. Next, inverse Fourier transform or least squares operations is performed on the multiplied values to compute channel impulse response. The number of shifted impulse response in the channel impulse response represents the detected number of transmit antennas. Packets containing preambles of the present invention may be received by extended devices as well as by legacy receivers that are not configured to receive and interpret these preambles. The training symbols may be cyclically-shifted and transmitted on different transmit antennas.
摘要:
Methods and systems for signaling on a mixed-mode wireless network comprising a plurality of channels are provided. The mixed-mode wireless network includes high-throughput (HT) wireless devices and legacy wireless devices that use channels of the same width. The HT devices transmit data on at least two channels, while the legacy devices transmit on one channel. The distances between the HT channels and the distances between the legacy channels might differ, however, the channels used by the HT devices and the legacy devices may overlap. As a result, cooperation between the HT devices and legacy devices is provided to enable the devices to coexist on the same wireless network by minimizing collisions and interference. The HT devices are configured to send control information to the legacy devices to coordinate transmission by the HT devices with the legacy devices.
摘要:
A modified preamble is used by extended devices that operate at higher rates, MIMO or other extensions relative to strict 802.11a-compliant devices. The extended devices might use multiple antenna techniques (MIMO), where multiple data streams are multiplexed spatially and/or multi-channel techniques, where an extended transmitter transmits using more than one 802.11a channel at a time. Such extensions to IEEE 802.11a can exist in extended devices. The modified preamble is usable for signaling, to legacy devices as well as extended devices, to indicate capabilities and to cause legacy devices or extended devices to defer to other devices such that the common communication channel is not subject to unnecessary interference. The modified preamble is also usable for obtaining MIMO channel estimates and/or multi-channel estimates. The modified preamble preferably includes properties that facilitate detection of conventional and/or extended modes (“mode detection”) and provides some level of coexistence with legacy IEEE 802.11 a devices.
摘要:
A digital modulation system provides enhanced multipath performance by using modified orthogonal codes with reduced autocorrelation sidelobes while maintaining the cross-correlation properties of the modified codes. For example, the modified orthogonal codes can reduce the autocorrelation level so as not to exceed one-half the length of the modified orthogonal code. In certain embodiments, an M-ary orthogonal keying (MOK) system is used which modifies orthogonal Walsh codes using a complementary code to improve the auto-correlation properties of the Walsh codes, thereby enhancing the multipath performance of the MOK system while maintaining the orthogonality and low cross-correlation characteristics of the Walsh codes.
摘要:
A MIMO transmitter including an interleaving system for parsing encoded bits to a plurality of spatial streams and a plurality of interleavers to interleave bits for spatial streams such that at least a first spatial stream uses a first stream interleaver that interleaves with a pattern distinct from a second stream interleaver interleaving for a second spatial stream.