Abstract:
A multi-carrier communication system such as an OFDM or DMT system has nodes which are allowed to dynamically change their receive and transmit symbol rates, and the number of carriers within their signals. Changing of the symbol rate is done by changing the clocking frequency of the nodes' iFFT and FFT processors, as well as their serializers and deserializers. The nodes have several ways of dynamically changing the number of carriers used. The selection of symbol rate and number of carriers can be optimized for a given channel based on explicit channel measurements, a priori knowledge of the channel, or past experience. Provision is made for accommodating legacy nodes that may have constraints in symbol rate or the number of carriers they can support. The receiver can determine the correct symbol rate and number of carriers through a priori knowledge, a first exchange of packets in a base mode that all nodes can understand, or an indication in the header of the data packet which is transmitted in a base mode of operation that all nodes can understand.
Abstract:
This disclosure is directed to systems and methods that compensate for a phase change that results from a change in RF gain, a “phase glitch,” that would otherwise degrade the performance of a multiple sub-carrier communication system, such as OFDM. Pilot symbols are used to estimate the phase change, allowing the pilot and data symbols to be compensated by the estimated phase change. Preferably, the compensated pilots are used to per form a second iteration of phase change estimation that determines residual phase glitch. Thus, following the second estimation of phase change, data symbols can be compensated for the estimated residual phase change.
Abstract:
A method of providing synchronization-free station locating in a wireless network is provided. In this method, an AP having a known location sends a unicast packet to the station and notes its time of departure TOD(D). The station receives the unicast packet, notes its time of arrival TOA(D), sends an acknowledgement packet to the AP, and notes its time of departure TOD(D_ACK). The AP receives the acknowledgment packet and notes its time of arrival TOA(D_ACK). Notably, a distance between the AP and the station can be accurately determined using a first difference between the TOA(D_ACK) and the TOD(D) and a second difference between the TOD(D_ACK) and the TOA(D). A plurality of such computed distances between a plurality of APs and the station can be used to determine an accurate location of the station.
Abstract:
A method of providing synchronization-free station locating in a wireless network is provided. In this method, an AP having a known location sends a unicast packet to the station and notes its time of departure TOD(D). The station receives the unicast packet, notes its time of arrival TOA(D), sends an acknowledgement packet to the AP, and notes its time of departure TOD(D_ACK). The AP receives the acknowledgment packet and notes its time of arrival TOA(D_ACK). Notably, a distance between the AP and the station can be accurately determined using a first difference between the TOA(D_ACK) and the TOD(D) and a second difference between the TOD(D_ACK) and the TOA(D). A plurality of such computed distances between a plurality of APs and the station can be used to determine an accurate location of the station.
Abstract:
A powerline communication (PLC) network can be subject to noise/interference resulting in loss of throughput and data corruption for PLC devices connected to the PLC network. A powerline interference analyzer can be implemented in the PLC network for detecting sources of the noise. The powerline interference analyzer can determine powerline network noise characteristics that are representative of noise on the PLC network and can analyze the powerline network noise characteristics to determine one or more noise patterns. The noise patterns can be compared with a plurality of predefined noise signatures that are representative of corresponding each of a plurality of noise sources. Consequently, at least one noise source that is associated with the noise patterns can be identified from the plurality of the noise sources.
Abstract:
A polar transmitter includes a phase monitoring unit for monitoring input modulating data. When a phase transition exceeds a phase transition threshold, the phase monitor unit can signal an amplitude negation unit to invert the amplitude data coupled to the polar amplifier. The phase monitoring unit can also add an offset to the phase data that is provided to a frequency synthesizer. In another embodiment, when the phase transition threshold is exceeded, the phase monitoring unit can trigger inverting differential frequency data coupled to the polar amplifier. In one embodiment, the phase offset and the amplitude negation are applied until a second phase transition value exceeding the phase transition threshold is detected. If such an event is detected, then the input amplitude data is no longer inverted and the phase offset value is no longer added to the modulating data.
Abstract:
A dual band radio is constructed using a primary and secondary transceiver. The primary transceiver is a complete radio that is operational in a stand alone configuration. The secondary transceiver is a not a complete radio and is configured to re-use components such as fine gain control and fine frequency stepping of the primary transceiver to produce operational frequencies of the secondary transceiver. The primary transceiver acts like an intermediate frequency device for the secondary transceiver. Switches are utilized to divert signals to/from the primary transceiver from/to the secondary transceiver. The switches are also configured to act as gain control devices. Antennas are selected using either wideband or narrowband antenna switches that are configured as a diode bridge having high impedance at operational frequencies on control lines that bias the diodes.
Abstract:
A radio communication device is tested by forwarding relevant signal characteristic data derived at the physical (PHY) layer to the media access control (MAC) layer for processing, analysis and feedback to the radio circuit to improve performance. The relevant signal characteristics are forwarded to the MAC within (appended to) a data packet. Thus, the relevant signal characteristic is forwarded to the MAC along an existing data path (a path originally designed to transfer the receive frame only, but now transfers the combined receive frame with the attached radio characteristic). The radio characteristic may be used for testing and/or tuning the radio circuit. In one embodiment, the radio characteristic is a frequency domain representation of a received signal. The radio is tuned based on a channel estimate derived from comparison of frequency domain representations of transmitted and received signals.
Abstract:
Various regulatory domains promulgate standards to define how wireless devices should operate in certain frequency bands. The 5 GHz spectrum is of particular importance to certain regulatory domains because of radar systems also operating in this spectrum. To avoid interference with such radar systems, wireless devices operating in this spectrum should be able to detect radar and quickly vacate any channels currently used by the radar systems. Techniques are provided for performing startup scans for radar, identifying backup channels for a possible channel switch, and efficiently changing channels in the event of radar detection in the operating channel. These techniques advantageously meet current regulatory standards governing DFS while minimizing network startup delays and disruption to users during a radar event.
Abstract:
A method and apparatus to selectively disregard co-channel transmissions on a medium uses an automatic gain control/clear channel assessment (AGC/CCA) circuit to gather signal power information, which is used to establish receiver sensitivity thresholds. Raw and cyclical power measurements of a received signal are processed by the AGC/CCA circuit to determine whether a current received signal process should be halted, and a new signal acquisition sequence begun.