摘要:
In a direct sequence spread spectrum data communication system an information bit is mixed with a pseudorandom noise or spreading code to produce modulated codeword for transmission. A method of bandwidth efficient M-ary phase shift key modulation encoding at least 16 bits of data to a single codeword is disclosed for extending the data rate of a spread spectrum system. Interoperability with legacy devices is maximized by maintaining structural similarity between the modulated waveforms of the extended data rate and legacy systems.
摘要:
A wideband receiver, including a time-varying finite impulse response (FIR) filter, has been provided to combine multipath communications of data in response to pilot channel timing information. The time-varying FIR processes the multipath communications through independent signal paths. Each signal path includes a variable delay circuit and a variable gain circuit. The delay of each separate signal path is adjusted and made equal in response to the pilot channel timing information. Likewise, the gain of each signal path is adjusted in response to pilot channel gain information to maximize the signal to noise ratio of the combined signal paths. The separate signal paths are then summed in a combiner circuit. The time-varying FIR permits the data communication to be summed either before, or after demodulation. A method of combining multipath communications using a time-varying FIR is also provided.
摘要:
The performance of forward error correction decoders for digital communication systems can be improved if soft information relating the reliability of the value representing the demodulated signal is provided to the decoder with a value for the signal. On the other hand, soft information increases the quantity of information that must be processed, increasing the cost and complexity of the decoder.
摘要:
A wideband CDMA receiver system to accept messages from asynchronously transmitting base stations is provided. The base station transmission to each receiver includes a perch channel and at least one traffic channel. Although all the channels typically include pilot symbols for the purpose of demodulating the information symbols of the channel, the pilot channel includes a higher proportion of pilot symbols to information symbols. Therefore, a perch channel based timing and estimation system is inherently more accurate. In addition, the perch channel is generally transmitted at higher power levels than a traffic channel, and the resulting, higher, signal to noise ratio signal also improves the accuracy of the timing and channel estimation. Based on the timing derived from the perch channel of a first base station, the receiver can set the timing of the traffic channel transmissions from a second base station, to more closely match the timing of traffic channel transmissions from the first base station. In this manner, the signal to noise ratio of the demodulated traffic channel information symbols is enhanced through the diversity of using the transmissions of two base stations. A method for receiving wideband CDMA transmissions from asynchronously transmitting base stations is also provided.
摘要:
A wideband receiver automatic frequency control (AFC) system which combines multipath or diverse antenna signals, before the carrier frequency error is determined, is provided herein. Rather than independently calculating the frequency error of each transmission path, frequency error is calculated after the multipath signals are summed together. Thus, only a single frequency detector circuit is required. The resulting automatic frequency control system has the accuracy of a system which combines the independently calculated frequency errors, with fewer steps of computation required. A method for combining multipath signals to calculate an average AFC frequency error is also provided.
摘要:
A method of selectively providing MIMO transmission/reception in a WLAN system includes using a TSPEC reservation and signaling mechanism to instantiate and tear down, dynamically, multi-channel operation in a WLAN; providing an inference algorithm to determine the minimum number of channels required to establish a TSPEC using a MIMO WLAN system; providing specific channel parameters as parameters to be negotiated in the TSPEC; providing frame exchange sequences to be used in Enhanced Distributed Coordinated Access contention based access and to be used in polled access; and providing a mechanism wherein an access point makes a decision as to whether to admit MIMO functionality on a given link, wherein a “link” is a set of communications between two specific WLAN stations.
摘要:
A method of selectively providing MIMO transmission/reception in a WLAN system includes using a TSPEC reservation and signaling mechanism to instantiate and tear down, dynamically, multi-channel operation in a WLAN; providing an inference algorithm to determine the minimum number of channels required to establish a TSPEC using a MIMO WLAN system; providing specific channel parameters as parameters to be negotiated in the TSPEC; providing frame exchange sequences to be used in Enhanced Distributed Coordinated Access contention based access and to be used in polled access; and providing a mechanism wherein an access point makes a decision as to whether to admit MIMO functionality on a given link, wherein a “link” is a set of communications between two specific WLAN stations.
摘要:
A system and method are provided for controlling bandwidth allocation in a wireless local area network (wLAN). The method comprises: expressing device bandwidth allocations in terms of a time base; in response to expressing the bandwidth allocation in terms of a time base, monitoring network communications; and, measuring the allocated bandwidths. The method may further comprise: establishing polling schedules in response to expressing the bandwidth allocation in terms of a time base; and, de-energizing devices in response to the polling schedules. Expressing device bandwidth allocations in terms of a time base includes establishing: an inter-transmission opportunity (TXOP) interval; and, a TXOP jitter. These fields are supplied in the IEEE 802.11e transmit specification (TSPEC). Then, de-energizing devices in response to the polling schedule includes disengaging transmission and receiving functions in the minimum TXOP intervals between polling events, where the minimum TXOP interval is the inter-TXOP interval minus the TXOP jitter.
摘要:
A system and method are provided for coordinating a power-save interval in an IEEE 802.11 wireless network. The method transmits a first frame from an access point (AP) to a quality of service station (QSTA) and receives an acknowledgement from the QSTA. In response to receiving the acknowledgement, the first frame is retransmitted from the AP to the QSTA and the retransmitted first frame is identified as the last frame in the transmission queue. An acknowledgement is received responsive to the retransmitted first frame and the next minimum service interval is timed in response to the retransmitted first frame.