A method and receiver are disclosed for mitigating or substantially canceling signal interference between signals detected at the receiver. Once a presumed interfering signal(s) is acquired, parameters are determined that allow the interferer(s) to be modeled. The phase invariance of the process eliminates the need to acquire the interferer's phase. An orthogonal projection (for projecting onto a detection subspace which is orthogonal to a subspace spanned by the interferer(s)) is applied to the composite of all signals (y) for thereby projecting y onto the detection subspace. The interference subspace is non-orthogonal to a representation of desired (but interfered) signal of the composite signals. With the receiver properly equipped to perform this projection operation, interfering signals, multipath, multipath-like, and structured jamming signals can be effectively diminished.

Mitigating interference in a signal

A system embodiment includes a first device and a second device configured to communicate over a selected wireless communication channel selected from a band of channels or over a selected set of channels used in an adaptive frequency hopping scheme. The first device is configured to transmit a probe signal that has a plurality of frequencies contained within the band of channels, and the second device is configured to determine a signal strength of the probe signal for each of a plurality of potential communication channels within the band of channels. The first and second devices configured to switch to another wireless communication channel based at least in part on the signal strength of the probe signal for each of a plurality of potential wireless communication channels.

Wireless communication with probing bandwith

An approach for selecting sets of communications channels involves determining the performance of communications channels. A set of channels is selected based on the results of performance testing and specified criteria. The participant generates data that identifies the selected set of channels and provides that data to other participants of the communications network. The participants communicate over the set of channels, such as by using a frequency hopping protocol. When a specified time expires or monitoring of the performance of the channel set identifies poor performance of the set of channels, the participant selects another set of channels for use in communications based on additional performance testing. By selecting channels based on the initial performance testing and performance monitoring, the communications network adaptively avoids channels with poor performance.

Approach for selecting communications channels based on performance

In wireless local area networks utilizing frequency-hopping between different channels spaced over an allotted frequency band, two or more groups of transceivers in close proximity may be arranged to operate satisfactorily with the full bandwidth available to each by arranging that their hop sequences are kept separate. This may be achieved by arranging for the hop sequence of one group or of each group to skip at intervals from one point to another in the sequence, chosen at random.

Wireless local area networks

The present invention relates to a method for planning radio cells. The method utilizes an exclusion matrix calculated on the basis of measured field strengths and an iterative allocating algorithm, which allows an adaptation of the cell planning to prevailing traffic demand. The method includes the following steps: the traffic demand is geographically estimated; an acceptable coverage of the traffic demand is produced with the aid of a number of cells with suitable transmitter powers and antenna arrangements; each cell is allocated a number of channels, which corresponds to the estimated traffic demand, having regard to a margin for acceptable blocking; coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base; an exclusion matrix is calculated on the basis of the measurement results, which matrix represents the interaction between the cells in the system; an allocating algorithm is iterated, which algorithm, by utilizing a random technique, provides different collections of channel allocations for the cells; if the channel allocation is not possible with regard to the number of channels in a given frequency band, a new attempt is made and the subsequent steps are repeated; if the number of channels was sufficiently high, a radio cell design is obtained which is acceptable from the point of view of interference and the point of view of blocking. The present invention also provides a method for constructing the exclusion matrix and a method for determining uplink interferences.

Method for planning radio cells

A high frequency (HF) frequency-management system for automatically selecting optimum HF frequency. A frequency management means controls the operation of a regular HF radio communications transmitter and receiver at each station. The frequency-management means transmits sounding signals synchronously and repeatedly over a finite group of HF frequencies, from a first radio communications station to a second radio communications station. Link quality evaluation (LQE) is carried out at the second station. Sounding signals are transmitted synchronously and repeatedly back to the first station. Optimum HF frequencies are selected based on the sounding signals and LQE. An HF communications path is automatically established between stations. The system performs the scanning of the HF frequencies, the detection and measurement of signals, noise and interferences on each frequency and the timing synchronization as required for the frequency management operation.

Joseph M. Perl

Papers

Frequency management system