Abstract: A method and corresponding apparatus are provided to reduce the complexity of calculations needed to determine the time of arrival of position reference signals transmitted from multiple cells. A scheduler determines at a given instance what portions of a search grid or search window to search. A timing estimation circuit operating under the control of the scheduler computes timing estimates and reports the timing estimates back to the scheduler. The scheduler uses the timing estimates reported by the detection circuit to scheduler subsequent searches of the search grid or search window.

Abstract: The invention relates to a method performed in a user equipment for estimating channel quality. The user equipment is adapted to operate in a multiple input multiple output (MIMO) mode in a communication system comprising a base station node supporting MIMO and serving the user equipment. The method comprises: receiving, from the base station node, a reference signal; performing joint demodulation of the reference signal, thereby obtaining soft values; and generating the channel quality using the soft values. The invention also relates to a user equipment, computer programs and computer program products.

Abstract: Digital IQ imbalance compensation is utilized for a dual-carrier double conversion receiver. First, the effect of IQ imbalance on OFDM-based digital baseband is analyzed, showing that, in the presence of IQ imbalance, the baseband signal of each carrier is obtained from its own branch as well as the other branch. Second, IQ imbalance parameters of interest are estimated using pilot signals and compensated using only digital baseband processing.

Abstract: Methods and apparatus are provided for detecting the radio access technology (RAT) employed in a received signal prior to performing a cell search. The RAT detection method may be used to identify the most likely RAT employed for each candidate frequency identified in an initial frequency scan. Once the most likely RAT is identified, the mobile communication device can then attempt synchronization according to the procedures for the most likely RAT. Identifying the RAT prior to the cell search reduces the number of synchronization attempts and, consequently, the time needed to perform the cell search.

Abstract: Methods and apparatus in a receiver for estimating a received power of at least one signal having a pattern known to the receiver, the signal having being transmitted by at least one antenna. A method includes using a first method of measuring the received power based on the pattern, the first method generating a first sequence of first power estimates; determining whether a predetermined first event has occurred; and if the first event has occurred, changing to a second method of measuring the received power, the second method being different from the first method and generating a second sequence of second power estimates.

Abstract: A technique for cell signature determination in a cellular communication network is provided. A method implementation of this technique comprises the steps of providing a set of hypothesis signals, each hypothesis signal including a signature hypothesis, receiving a composite signal including a first signal portion carrying a first signature from a first cell and a second signal portion carrying a second signature from a second cell, wherein the first signal portion and the second signal portion overlap at least partially in time, and obtaining a correlation result by correlating the composite signal with each hypothesis signal. After the first signature has been determined, a set of phantom signatures associated with the first signature is provided. The phantom signatures represent artifacts from the first signal portion in the correlation result. Finally, the second signature is determined based on the correlation result taking into account the set of phantom signatures associated with the first signature.

Abstract: Methods and arrangements in a first network node, a second radio network node and a mobile terminal for enabling estimation of a position of a mobile terminal are provided. The first network node receives a request for estimating the position of the mobile terminal. The first network node determines a first set of radio network nodes including the second radio network node and two additional radio network nodes. The first network node determines positioning signals for transmission from radio network nodes of the first set to the mobile terminal. The first network node instructs each of the radio network nodes of the first set to transmit the positioning signal, associated therewith, to the mobile terminal.

Abstract: A mobile station comprises a radio communication unit (22) for communicating with a radio communication network for finding carriers on which transmissions are being made in active transmission intervals of a transmission cycle following a discontinuous transmission scheme. The radio communication unit is configured to select a carrier based on probability settings provided for each carrier of the scheme, scan the selected carrier during a time range that is a fraction of the transmission cycle, confirm the presence of the carrier if transmissions are detected and otherwise to adjust the probability settings of the carriers based on the timing of the scanning and the position of the carrier active transmission interval in the transmission sequence and repeat the selection of carrier based on probability settings and adjusting of probability settings until the presence of a carrier has been confirmed.

Abstract: Methods and apparatus are provided for detecting the radio access technology (RAT) employed in a received signal prior to performing a cell search. The RAT detection method may be used to identify the most likely RAT employed for each candidate frequency identified in an initial frequency scan. Once the most likely RAT is identified, the mobile communication device can then attempt synchronization according to the procedures for the most likely RAT. Identifying the RAT prior to the cell search reduces the number of synchronization attempts and, consequently, the time needed to perform the cell search.

Abstract: Digital IQ imbalance compensation is utilized for a dual-carrier double conversion receiver. First, the effect of IQ imbalance on OFDM-based digital baseband is analyzed, showing that, in the presence of IQ imbalance, the baseband signal of each carrier is obtained from its own branch as well as the other branch. Second, IQ imbalance parameters of interest are estimated using pilot signals and compensated using only digital baseband processing.

Abstract: A method of detecting a desired signal within a composite signal provides for suppression of interfering signal(s). The method, implemented in a wireless communication apparatus, for example, includes receiving the composite signal and obtaining sample values therefrom. At least some of the sample values include desired and interfering signal components. The method further includes generating an interfering signal channel estimate by: forming sample pairs for some or all of the sample values; identifying sample pairs of interest as those sample pairs in which the interfering signal component is the same; and calculating the interfering signal channel estimate as an average value determined from one or more of the sample pairs of interest. The method further includes detecting desired signal symbols from the composite signal in a joint detection process that functionally depends on the interfering signal channel estimate.

Abstract: Allocation of cell IDs in a cellular communication system includes determining a candidate allocation pattern of primary and secondary synchronization signal sequences for a candidate set of two or more cells. A performance metric is applied to the candidate allocation pattern to ascertain a performance indicator for the candidate allocation pattern, wherein the performance indicator indicates a quality of positioning performance for the candidate set of two or more cells. Cell-specific positioning performance for each cell in the candidate set of cells can be considered to derive the performance indicator of the candidate allocation pattern. If the performance indicator indicates acceptable positioning performance, primary and secondary synchronization signal sequences are allocated to respective ones of base stations corresponding to the two or more cells in accordance with the candidate allocation pattern. Otherwise, the process is repeated for a different candidate allocation pattern.

Abstract: Methods and arrangements in a first network node, a second radio network node and a mobile terminal for enabling estimation of a position of a mobile terminal are provided. The first network node receives a request for estimating the position of the mobile terminal. The first network node determines a first set of radio network nodes including the second radio network node and two additional radio network nodes. The first network node determines positioning signals for transmission from radio network nodes of the first set to the mobile terminal. The first network node instructs each of the radio network nodes of the first set to transmit the positioning signal, associated therewith, to the mobile terminal.

Abstract: There is disclosed a method of estimating frequency offset of a received signal in a terminal apparatus operating in a wireless communication system.

Abstract: A method and corresponding apparatus are provided to reduce the complexity of calculations needed to determine the time of arrival of position reference signals transmitted from multiple cells. A scheduler determines at a given instance what portions of a search grid or search window to search. A timing estimation circuit operating under the control of the scheduler computes timing estimates and reports the timing estimates back to the scheduler. The scheduler uses the timing estimates reported by the detection circuit to scheduler subsequent searches of the search grid or search window.

Abstract: A receiver receives and front-end processes a plurality of component carrier signals, each carrier spaced apart in frequency. The digitized, baseband component carrier signals are inspected to determine estimates of timing offsets between the carriers. A control unit selects a first component carrier signal having data scheduled to the receiver. If data is scheduled to the receiver on other component carrier signals, the control unit generates timing and frequency offset adjustment control signals to time- and frequency-align each other component carrier signal having relevant data, to the first component carrier signal. All the relevant component carrier signals are then combined, and a single OFDM symbol, spanning all the relevant component carriers, is presented to an FFT for symbol detection.

Abstract: A wireless communication system receiver receives and processes a signal comprising at least two component carriers carrying data scheduled to the receiver and having center frequencies spaced apart by at least one component carrier frequency difference. Each component carrier comprises a number of subcarriers spaced apart by a system subcarrier frequency spacing. A common divisor is obtained for the at least one component carrier frequency difference and the system subcarrier frequency spacing. A symbol is received on the subcarriers of the component carriers and downconverted to baseband to produce a baseband symbol. A block of padding values is inserted in the baseband symbol to produce a padded symbol. The length of the block of padding values is such that intermediate subcarriers are inserted to yield a subcarrier frequency spacing for the padded symbol equal to the common divisor. Finally the padded symbol is Fast Fourier Transform, FFT, processed.

Abstract: A frequency offset of a received signal comprising a number of subsequently received data symbols is estimated. A first estimate is determined from a calculated change in phase of the received signal between two received symbols having a first time distance between them. At least one further estimate is determined from a calculated change in phase of the received signal between two received symbols having a different time distance. A frequency periodicity is determined for each estimate from the distance between the two received symbols from which the estimate was determined. A set of integer values is determined for each estimate so that frequency values calculated for each estimate as the frequency periodicity multiplied by the integer value added to the estimate are at least approximately equal to each other, and a corrected estimate of the frequency offset is determined from the integer values.

Abstract: A terminal with transmitter and receiver operates in a multi-carrier communication system and receives at least two downlink carriers. One or more timing advance commands are received, each associated with a group of one or more uplink carriers, each group being associated with one or more of the received downlink carriers. For each downlink carrier associated with one of the groups of uplink carriers, one is selected as a reference downlink carrier; the reference downlink carrier timing is ascertained; and a transmission time period is ascertained based on the timing of the downlink reference carrier and an offset specified by the timing advance command associated with the group of uplink carriers. The transmission time period comprises a start time and a stop time. Transmission is initiated at an earliest transmission start time of the ascertained transmission time periods and is ceased at a latest ascertained stop time.

Abstract: An arrangement for estimating IQ-imbalance of a received OFDM-signal is disclosed. The arrangement comprises an FFT-unit (410) adapted to transform the received OFDM-signal to a frequency domain. The frequency domain comprises a plurality of sub-carrier frequencies, and the transformed received OFDM-signal comprises pilot symbols on one or more sub-carrier frequencies and symbols other than pilot symbols on one or more other sub-carrier frequencies. The arrangement also comprises channel estimation circuitry (430, 445), and an IQ-imbalance estimation unit (440) adapted to estimate the IQ-imbalance based on at least one of the pilot symbols, a determined estimated channel value for the sub-carrier frequency of the at least one pilot symbol, an estimate of the transmitted information symbol on the corresponding mirror sub-carrier frequency associated with the at least one pilot symbol and an estimated channel value for the corresponding mirror sub-carrier frequency associated with the at least one pilot symbol.