公开(公告)号：US10142154B2

公开(公告)日：2018-11-27

申请号：US15921462

申请日：2018-03-14

Applicant: Imagination Technologies Limited

Inventor： Mohammed Alloulah ,  Paul Murrin ,  Alamo Spaargaren

IPC: H04L27/26 ,  H04L25/03 ,  H04L25/02

Abstract: Methods and OFDM receivers for decoding an OFDM signal include estimating a channel impulse response from a pilot-dense symbol of the OFDM signal for each of a plurality of potential FFT window positions; determining a noise floor of each of the channel impulse responses; selecting the potential window position corresponding to the channel impulse response with the lowest noise floor as an optimum FFT window position; and decoding symbols of the OFDM signal using the optimum FFT window position.

公开(公告)号：US20160294597A1

公开(公告)日：2016-10-06

申请号：US15181687

申请日：2016-06-14

Applicant: Imagination Technologies Limited

Inventor： Mohammed El-Hajjar ,  Paul Murrin ,  Adrian J. Anderson

IPC: H04L27/26

CPC classification number: H04L27/2647 ,  H03M13/41 ,  H04L1/0054 ,  H04L1/06 ,  H04L1/0618 ,  H04L25/067 ,  H04L27/38

Abstract: Methods and apparatus for efficient demapping of constellations are described. In an embodiment, these methods may be implemented within a digital communications receiver, such as a Digital Terrestrial Television receiver. The method reduces the number of distance metric calculations which are required to calculate soft information in the demapper by locating the closest constellation point to the received symbol. This closest constellation point is identified based on a comparison of distance metrics which are calculated parallel to either the I- or Q-axis. The number of distance metric calculations may be reduced still further by identifying a local minimum constellation point for each bit in the received symbol and these constellation points are identified using a similar method to the closest constellation point. Where the system uses rotated constellations, the received symbol may be unrotated before any constellation points are identified.

公开(公告)号：US20130329838A1

公开(公告)日：2013-12-12

申请号：US13760361

申请日：2013-02-06

Applicant: IMAGINATION TECHNOLOGIES LIMITED

Inventor： Mohammed El-Hajjar ,  Paul Murrin ,  Adrian J. Anderson

IPC: H04L1/00

CPC classification number: H04L27/2647 ,  H03M13/41 ,  H04L1/0054 ,  H04L1/06 ,  H04L1/0618 ,  H04L25/067 ,  H04L27/38

Abstract: Methods and apparatus for efficient demapping of constellations are described. In an embodiment, these methods may be implemented within a digital communications receiver, such as a Digital Terrestrial Television receiver. The method reduces the number of distance metric calculations which are required to calculate soft information in the demapper by locating the closest constellation point to the received symbol. This closest constellation point is identified based on a comparison of distance metrics which are calculated parallel to either the I- or Q-axis. The number of distance metric calculations may be reduced still further by identifying a local minimum constellation point for each bit in the received symbol and these constellation points are identified using a similar method to the closest constellation point. Where the system uses rotated constellations, the received symbol may be unrotated before any constellation points are identified.

Abstract translation: 描述了有效地拆分星座的方法和装置。 在一个实施例中，这些方法可以在诸如数字地面电视接收机的数字通信接收机内实现。 该方法减少了通过将最接近的星座点定位到接收到的符号来计算解映射器中的软信息所需的距离度量计算的数量。 基于与I轴或Q轴平行计算的距离度量的比较来识别最接近的星座点。 通过识别接收到的符号中的每个位的局部最小星座点，可以进一步减少距离度量计算的数量，并且使用与最接近的星座点类似的方法来识别这些星座点。 在系统使用旋转星座的地方，在识别出任何星座点之前，接收到的符号可能未旋转。

公开(公告)号：US11184110B2

公开(公告)日：2021-11-23

申请号：US17086576

申请日：2020-11-02

Applicant: Imagination Technologies Limited

Inventor： Filipe Carvalho ,  Paul Murrin

IPC: H04L1/00 ,  H04L1/24

Abstract: Channel state information (CSI) scaling modules for use in a demodulator configured to demodulate a signal received over a transmission channel, the demodulator comprising a soft decision error corrector (e.g. LDPC decoder) configured to decode data carried on data symbols of the received signal based on CSI values. The CSI scaling module is configured to monitor the performance of the soft decision error corrector and in response to determining the performance of the soft decision error corrector is below a predetermined level, dynamically select a new CSI scaling factor based on the performance of the soft decision error corrector.

公开(公告)号：US11044128B2

公开(公告)日：2021-06-22

申请号：US16920849

申请日：2020-07-06

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin ,  Adrian John Anderson

IPC: H04L27/14 ,  H04L1/00 ,  H04L27/20 ,  H03M13/23 ,  H03M13/25 ,  H04L27/00

Abstract: A gaussian frequency shift keying (GFSK) detector comprising a multi-symbol detector; at least three Viterbi decoders, and a timing adjustment module. The multi-symbol detector receives a series of samples representing a received GFSK modulated signal which comprises at least three samples per symbol; and generates, for each set of samples representing an N-symbol sequence of the GFSK modulated signal, at least three sets of soft decisions values, each set of soft decision values indicating the probability that the N-symbol sequence of samples is each possible N-symbol pattern based on a different one of the at least three samples of a symbol being a centre sample of the symbol. Each Viterbi decoder generates, for each N-symbol sequence, a path metric for each possible N-symbol pattern from a different set of soft decision values according to a Viterbi decoding algorithm. The timing adjustment module generates a timing adjustment signal based on the path metrics generated by the Viterbi decoders to adjust the sample timing.

公开(公告)号：US10296456B2

公开(公告)日：2019-05-21

申请号：US13794796

申请日：2013-03-12

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin ,  Adrian J. Anderson ,  Mohammed El-Hajjar

IPC: G06F12/06 ,  H03M13/27 ,  H03M13/00

Abstract: Tile based interleaving and de-interleaving of row-column interleaved data is described. In one example, the de-interleaving is divided into two memory transfer stages, the first from an on-chip memory to a DRAM and the second from the DRAM to an on-chip memory. Each stage operates on part of a row-column interleaved block of data and re-orders the data items, such that the output of the second stage comprises de-interleaved data. In the first stage, data items are read from the on-chip memory according to a non-linear sequence of memory read addresses and written to the DRAM. In the second stage, data items are read from the DRAM according to bursts of linear address sequences which make efficient use of the DRAM interface and written back to on-chip memory according to a non-linear sequence of memory write addresses.

公开(公告)号：US10255161B2

公开(公告)日：2019-04-09

申请号：US15079580

申请日：2016-03-24

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin ,  Gareth Davies

IPC: G06F11/00 ,  G06F11/36 ,  G06F17/40 ,  G06F11/34

Abstract: A logging unit is used to log entries for events in a computer system. Each entry includes an n-bit timestamp field and a payload. The payload includes information about the event and the timestamp field includes the n least significant bits of an N-bit timestamp for the event, where N>n. If the n least significant bits of the timestamp have wrapped compared to the corresponding n bits of the timestamp of the preceding entry then a timing entry is logged which includes other bits of the timestamp. Therefore, an N-bit timestamp can be determined for an event, but only the n least significant bits of the timestamp are stored in the timestamp field of an entry for the event. Therefore, the time flow of events in the store is better maintained (by having a larger timestamp) without increasing the number of bits (n) in the timestamp field of each entry.

公开(公告)号：US20160359579A1

公开(公告)日：2016-12-08

申请号：US15172463

申请日：2016-06-03

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin ,  Bastien Beauvois ,  Nitzan Tzifroni

IPC: H04J11/00 ,  H04W24/08 ,  H04W72/04 ,  H04L29/06

CPC classification number: H04J11/005 ,  H04L27/2607 ,  H04L27/2659 ,  H04L27/2678 ,  H04L27/2686 ,  H04L69/22 ,  H04W24/08 ,  H04W72/0453

Abstract: A non-data-aided method of calculating an estimate of the sampling frequency offset (SFO) in a digital receiver involves performing a plurality of correlations between two identical sized groups of samples within a received signal where the spacing of the groups is varied for each correlation. In various examples the number of samples in the groups is also varied. For larger symbols, the group of samples may comprise approximately the same number of samples as the guard interval in a symbol and for smaller symbols, the group of samples may comprise approximately the same number of samples as an entire symbol. An estimate of the SFO is determined by identifying the largest correlation result obtained from all the correlations performed. The largest correlation result indicates the largest correlation.

Abstract translation: 用于计算数字接收机中的采样频率偏移（SFO）的估计的非数据辅助方法涉及在接收信号中的两个相同大小的样本组之间执行多个相关性，其中组的间隔对于每个样本 相关性。 在各种实施例中，组中的样品数也是变化的。 对于较大的符号，样本组可以包括与符号中的保护间隔大致相同数量的采样，对于较小的符号，采样组可以包括与整个符号大致相同数量的采样。 通过识别从执行的所有相关性获得的最大相关结果来确定SFO的估计。 最大相关结果表明最大相关。

公开(公告)号：US20160283312A1

公开(公告)日：2016-09-29

申请号：US15079580

申请日：2016-03-24

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin ,  Gareth Davies

IPC: G06F11/07

CPC classification number: G06F11/3636 ,  G06F11/3466 ,  G06F11/3476 ,  G06F17/40 ,  G06F2201/835 ,  G06F2201/86

Abstract: A logging unit is used to log entries for events in a computer system. Each entry includes an n-bit timestamp field and a payload. The payload includes information about the event and the timestamp field includes the n least significant bits of an N-bit timestamp for the event, where N>n. If the n least significant bits of the timestamp have wrapped compared to the corresponding n bits of the timestamp of the preceding entry then a timing entry is logged which includes other bits of the timestamp. Therefore, an N-bit timestamp can be determined for an event, but only the n least significant bits of the timestamp are stored in the timestamp field of an entry for the event. Therefore, the time flow of events in the store is better maintained (by having a larger timestamp) without increasing the number of bits (n) in the timestamp field of each entry.

Abstract translation: 记录单元用于记录计算机系统中事件的条目。 每个条目包括n位时间戳字段和有效载荷。 有效载荷包括关于事件的信息，并且时间戳字段包括事件的N位时间戳的n个最低有效位，其中N> n。 如果时间戳的n个最低有效位与先前条目的时间戳的相应n位相比较，则记录包括时间戳的其他位的定时条目。 因此，可以为事件确定N位时间戳，但是时间戳的n个最低有效位仅存储在事件的条目的时间戳字段中。 因此，在不增加每个条目的时间戳字段中的位数（n）的情况下，更好地维持存储器中的事件的时间流（通过具有较大的时间戳）。

公开(公告)号：US20150110207A1

公开(公告)日：2015-04-23

申请号：US14505674

申请日：2014-10-03

Applicant: Imagination Technologies Limited

Inventor： Paul Murrin

IPC: H04L25/02 ,  H04L27/26

CPC classification number: H04L25/0212 ,  H04L25/0232 ,  H04L27/2613 ,  H04L27/2647 ,  H04L27/2665

Abstract: Distortion caused by spurious components in a determined channel impulse response (CIR) is reduced. In an OFDM (orthogonal frequency-division multiplexing) system pilot signals are applied to different subcarriers of different symbols in accordance with a pilot transmission scheme. Channel estimates are determined by time-interpolation for some of the data slots of the received signal which do not already include a pilot signal. For each of a sequence of symbols, a respective Inverse Fast Fourier Transform is performed on the pilot signals and interpolated channel estimates in the data slots of that symbol, thereby determining a sequence of estimated CIRs for the sequence of symbols. Spurious channel components will vary across the sequence of estimated CIRs, whereas the true channel peaks will tend not to significantly vary across the sequence of estimated CIRs. Therefore the sequence of estimated CIRs can be filtered (e.g. with a low-pass filter) to attenuate the spurious components, thereby determining a CIR for the signal for which the distortion caused by the spurious components is reduced.

Abstract translation: 在确定的信道脉冲响应（CIR）中由杂散分量引起的失真减少。 在OFDM（正交频分复用）系统中，导频信号根据导频传输方案应用于不同符号的不同子载波。 信道估计由接收信号的一些未包括导频信号的数据时隙的时间插值确定。 对于符号序列中的每一个，对该符号的数据时隙中的导频信号和内插信道估计执行相应的快速傅里叶逆变换，从而确定符号序列的估计CIR的序列。 杂散信道分量将在估计的CIR的序列上变化，而真实的信道峰值在估计的CIR的序列上将趋于不显着变化。 因此，可以对估计的CIR的序列进行滤波（例如，使用低通滤波器）来衰减杂散分量，由此确定由于杂散分量导致的失真减小的信号的CIR。