Abstract:
There is provided a receiver comprising a processing unit, a communications unit for receiving frames including training sequence symbols or pilot symbols, the processing unit being configured to use Cyclic Redundancy Check for detecting errors in the received frames. When no errors in a given frame are discovered on the basis of the Cyclic Redundancy Check, the processing unit is further configured to define a TSC, training sequence code, bit error rate for the bursts of the given frame on the basis of the training sequence symbols or the pilot symbols; to define an upper limit for the TSC bit error rate; and to determine the given frame to be bad when the TSC bit error rate for the bursts of the given frame is greater than the upper limit of the TSC bit error rate.
Abstract:
Erasure detection and power control are performed for an intermittently active transport channel with unknown format. A receiver processes each received block and determines whether it passes or fails CRC. For each received block with CRC failure, the receiver performs erasure detection by computing a symbol error rate (SER) and energy of the received block, comparing the computed SER against an SER threshold, comparing the computed energy against an energy threshold, and declaring an erasure if the computed SER is less than the SER threshold and the computed energy exceeds the energy threshold. The SER and energy thresholds may be adjusted based on the average SER and the average energy for prior received blocks with CRC failures. For power control, an SIR target is increased by an UP step whenever an erased block is detected for the transport channel.
Abstract:
A system and method for bad frame indication of a speech frame includes estimating a signal-to-noise ratio (SNR) and checking a cyclic redundancy code (CRC) value of the speech frame. When the speech frame fails CRC error detection or the SNR is below a pre-specified value, a bad frame indication (BFI) flag is set. When the speech frame passes CRC error detection and the SNR is above the pre-specified value, a receive signal quality metric of the speech frame is checked against a high threshold and, if need be, a low threshold. The BFI flag and the receive signal quality metric for the previous speech frame is checked when the current receive signal quality metric is between the high and low thresholds. The BFI flag is set according to the value of the SNR, the CRC value, the current and previous receive signal quality metrics, and the previous BFI flag.
Abstract:
An apparatus and method of detecting whether data exists in a received signal while a mobile communication terminal is in discontinuous transmission mode is disclosed. The apparatus and method comprises generating and transmitting a forward power control command for providing the forward power control, and performing forward power control in a mobile communication system. According to the forward power control method, a power control command is generated based on a received frame including a plurality of slots each of which includes power control bits. The ratio of the power control bit energy to noise energy, which is given by a ratio of the accumulated energy of the power control bits in the slots of the received frame to an accumulated energy value of noise in the slots of the received frame, is provided, and the power control command based on a ratio of the accumulated energy value of traffic symbol bits in the slots to the accumulated energy value of the power control bits is generated when the provided ratio of the power control bits to noise is acceptable.
Abstract:
This is a method and apparatus for supervising a potentially gated channel in a wireless communication system. The mobile station (4) maintains a counter of consecutive bad frames, COUNT1 (224), and a counter of consecutive good frames, COUNT2 (226). COUNT1 (224) and COUNT2 (226) are set to zero at the beginning of a call. For each frame received, the mobile station (4) determines if it is a good, bad, or an empty frame. If the received frame is good, COUNT1 (224) is reset to zero and COUNT2 (226) is incremented by 1. If the received frame is bad, COUNT1 (224) is incremented by one and COUNT2 (226) is reset to zero. If the received frame is empty, COUNT1 (224) and COUNT2 (226) are unchanged. If COUNT1 (224) reaches a threshold value, TH1, the mobile station (4) shall disable its transmitter. Thereafter, if COUNT2 (226) reaches a threshold value, TH2, the mobile station (4) shall re-enable its transmitter.
Abstract:
In a digital radio communication system in which information is transmitted and received in time slots and some bits of each received audio frame is interleaved over at least two time slots and other bits in each audio frame are non-interleaved, bad received audio frames are detected by detecting (110) possible bit errors in a channel encoded non-interleaved bit sequence in each received time slot. If bit errors have been detected in this bit sequence a bad received frame is indicated.
Abstract:
In a communication system in which direct sequence spread spectrum modulation techniques are used, interference is generated in communications by remote stations since the communications share the same frequency spectrum. In order to increase system capacity the power level of the remote station transmitters are controlled by the local station. A setpoint in generated at the local station by a power control processor (118) and compared by a comparator (120) with the remote station signal strength measured at the local station by a power averager (114). The result of this comparison is used to generate power level adjustment commands by a command generator (122) which are transmitted to the remote station. The remote station is responsive to the power level adjustment commands for increasing or decreasing remote station transmitter power. In a spread spectrum communication system in which data is encoded at variable data rates, the local station determines via a rate determination processor (116) the rate at which received data was encoded by the transmitting remote station. The data is decoded by decoder (112) at each possible rate with error metrics generated that are representative of the quality of the data decoded at each rate. A rate decision algorithm is used by processor (116) to evaluate the error metrics and make a decision on the rate at which the data was transmitted. A pattern match of rate decisions is used by processor (118) to modify a setpoint so as to closely control the transmitting power of the remote station as a function of the quality of the received data.
Abstract:
An error detector circuit (300), and an associated method, is disclosed for a discrete receiver, the error detector circuit (300) indicates bad frames of binary information signals which contain distorted bits of data in numbers so great as to prevent a convolutional decoder (312) from generating, accurately, a decoded signal. When bit errors are detected in numbers beyond a first preselected value of signal quality of a received signal combined with the detected number of bits errors forming a signal beyond a second preselected value, a bad frame is detected.