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:
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:
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:
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:
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:
In a wireless transmitter having a plurality of spatial streams differentiable at a receiver, wherein data is encoded and transmitted over a communication channel with pilot tones to provide the receiver with information about the effects of the communication channel and/or transmitter impairments and/or receiver impairments on the spatial streams transmitted, the benefits can be provided by identifying a plurality of symbol periods within which symbols representing some of the encoded data are to be transmitted, identifying pilot tone values for the plurality of symbol periods, wherein the identified pilot tone values are such that the receiver, when receiving at least some of the pilot tones having the identified pilot tone values, is provided with signals enabling the receiver to characterize the communication channel and/or transmitter impairments and/or receiver impairments to obtain transmit stream diversity gain, and transmitting the symbols and the pilot tones over the plurality of spatial streams for the plurality of symbol periods. In some embodiments, the pilot tones are orthogonal over space and time or over space and time and frequency, while in others they are semi-orthogonal. Pilot tone values might be of a constant amplitude and phase shifted, or might also have amplitude variations wherein at least two pilot tones are nonzero for spatial streams for a given symbol period.
摘要:
Systems and methods for wide frequency offset synchronization are provided. A synchronization data sequence is encoded onto a series of OFDM frequency domain bursts as interburst phase differences between training symbols included within the successive bursts. The interburst phase differences may also encode system configuration information. This technique may be used in conjunction with other synchronization techniques to greatly extend the frequency acquisition range achievable with low cost analog components.
摘要:
A space-time signal processing system with advantageously reduced complexity. The system may take advantage of multiple transmitter antenna elements and/or multiple receiver antenna elements, or multiple polarizations of a single transmitter antenna element and/or single receiver antenna element. The system is not restricted to wireless contexts and may exploit any channel having multiple inputs or multiple outputs and certain other characteristics. Multi-path effects in a transmission medium cause a multiplicative increase in capacity.
摘要:
A wireless network includes a transmitting device and a plurality of receiving devices. The transmitting device is configured to receive a plurality of data packets, including a first data packet and a second data packet, prepare a preamble, prepare a signal field for each of the plurality of data packets, including a first signal field based on the first data packet and a second signal field based on the second data packet, and broadcast the preamble, the first signal field, the first data packet, the second signal field, and the second data packet as a concatenated packet.
摘要:
A space-time signal processing system with advantageously reduced complexity. The system may take advantage of multiple transmitter antenna elements and/or multiple receiver antenna elements, or multiple polarizations of a single transmitter antenna element and/or single receiver antenna element. The system is not restricted to wireless contexts and may exploit any channel having multiple inputs or multiple outputs and certain other characteristics. Multi-path effects in a transmission medium cause a multiplicative increase in capacity.