Abstract:
When all of the fingers of a wireless rake receiver are “out-of-lock,” the transmit power is initially maintained at a constant level. When the “out-of-lock” condition persists for an extended period of time, transmit power is increased in an effort to reacquire a lock with a subscriber unit or base station, as the case may be. An increase in transmit power may be effective in reacquiring lock when the cause of the out-of-lock condition is slow fading, rather than fast fading. Slow fading may be evidenced by persistence of the out-of-lock condition for an extended period of time. The length of the out-of-lock condition is used to selectively control transmit power and thereby promote quality of service. Transmit power is only increased when the fingers remain out-of-lock for an extended period of time, thereby avoiding undue increases in transmit power that could produce interference among different subscriber units.
Abstract:
The mobility of mobile subscribers within a wireless digital communications system is estimated based on highway maps and traffic data. Cells within the network are modelled as nodes connected by edges where neighboring cells are connected by roads. Each edge has two edge weight components representing traffic flow from one cell to the other and vice versa. The edge weight components are calculated from terrain factors based on the size or capacity of the roads connecting the two cells and the total traffic within the subject cell, which information may be obtained from commercial geographic databases and/or government agencies. The resulting edge weight represents an expected number of handoffs between the two cells. The problem of partitioning cells among available switches within the network is thus reduced to the purely mathematical problem of minimizing the total edge weights of edges intersected by the partition boundaries. Existing mathematical optimization techniques for optimizing node-edge systems may therefore be applied to reduce the total number of expected inter-switch handoffs as mobile subscribers pass from cell to cell within the network.
Abstract:
The optimal power allocation process of the present invention allocates power between two base stations, serving a given mobile radiotelephone, during soft hand-off. A minimum total transmit power is chosen initially. The minimum total transmit power level, the path losses for each base station, the maximum transmit power for each base station, and the minimum allowed received power are all used to generate a range of values for a transmit power level multiplier, .alpha.. The multiplier is used to allocate the total transmit power among the base stations. This process is performed until the probability of bit error is less than a maximum threshold.
Abstract:
Systems, methods and computer program products for determining a position location estimate for a remote receiver based on one or more time-of-arrival measurements transmitted from one or more transmitters and first timing data associated with the one or more transmitters and further associated with one or more reference locations within a reference area of the remote receiver are described.
Abstract:
An improved method and apparatus for Mobile Transmit Diversity (MTD), or Uplink Transmit Diversity (ULTD) is disclosed. The mobile device either selects the best antenna at any given time, or transmits from both antennas using the best beam forming phase without feedback from the base station on which antenna to transmit from or which phase to use if using two antennas. Essentially operating in Open Loop MTD, a Hybrid Phase Sweeping algorithm requires testing of a fraction of phase hypotheses resulting in improved base station performance and higher data rates for the user.
Abstract:
An improved method and apparatus for Mobile Transmit Diversity (MTD), or Uplink Transmit Diversity (ULTD) is disclosed. The mobile device either selects the best antenna at any given time, or transmits from both antennas using the best beam forming phase without feedback from the base station on which antenna to transmit from or which phase to use if using two antennas. Essentially operating in Open Loop MTD, a Hybrid Phase Sweeping algorithm requires testing of a fraction of phase hypotheses resulting in improved base station performance and higher data rates for the user.
Abstract:
A cross product is determined for a received signal. A dot product is also determined for the received signal. If the cross product is greater than a predetermined threshold, the cross product is decremented by the product of the dot product multiplied by a constant value. If the cross product is less than or equal to the predetermined threshold, the cross product is incremented by the product of the dot product multiplied by the constant value. The incrementing or decrementing is continued until the frequency error approaches a minimum value.
Abstract:
Techniques for incorporating non-pilot symbols along with pilot symbols to improve the estimate of the characteristics (e.g., amplitude and phase) of a communication link. A pilot filter weighs samples corresponding to pilot and non-pilot symbol by different sets of coefficients, which have values determined by and/or corresponding to the confidence in the detected sample. Samples corresponding to pilot symbols are typically associated with higher degree of confidence and are weighted more (e.g., with weights of 1.0). Samples corresponding to non-pilot symbols are typically associated with lower confidence and are weighted with values that may be variable and dependent on the degree of confidence in the samples (e.g., with weights ranging from 0.0 up to 1.0). The weights are updated based on a particular estimator such as a MAP (Maximum a Posteriori) estimator, a MLE (Maximum Likelihood Estimator), or some other estimator.
Abstract:
In one embodiment, the invention is directed toward methods for estimating the power of a received signal encoded with both pilot and non-pilot symbols. The method may include separately accumulating the pilot symbols and the non-pilot symbols and then estimating signal power by calculating a weighted sum of the accumulated pilot and non-pilot symbols. In this manner, a more accurate estimate of the power of the received signal can be obtained.
Abstract:
A method for designing a soft handoff region in a wireless communications system. An inner region having an outer edge defined by a first radius is selected, wherein a mobile station communicates only with the base station within the inner region and has a selected outage probability at the outer edge of the inner region. Next, a soft handoff region having an outer edge defined by a second radius and an inner edge defined by the first radius is selected, wherein the mobile station within the soft handoff region has the selected outage probability. Actual coverage region having an outer edge defined by a third radius, wherein the third radius is selected to match soft handoff regions of other cells adjacent to the cell.