Spatial and temporal pre-equalization

A pre-equalization and timing technology, applied in the field of WCDMA communication systems, can solve problems such as far from optimal receivers

Active Publication Date: 2012-09-12
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the presence of multi-user interference (MUI), as is commonly encountered in cellular systems, the noise can be colored and the rake receiver is no longer optimal, and may even be far from optimal at all

Method used

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  • Spatial and temporal pre-equalization
  • Spatial and temporal pre-equalization
  • Spatial and temporal pre-equalization

Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0068] In the first embodiment of the present invention, both temporal pre-equalization and spatial pre-equalization can be performed in a single stage (7, 8), as shown in FIG. 3 . For the frequency index , the frequency-domain samples received from all antennas (1A, 1B) are represented by

[0069] , which is based on the time interval (or block) of received samples. This block passes to enumerate. Frequency-domain spatial and temporal pre-equalization (8) as with The element-wise multiplication of . we got

[0070]

[0071] in

[0072]

[0073] and among them is the frequency-domain representation of a scalar spectral shaping filter (SSF), such as a raised cosine filter. it's here, is the result of the Cholesky factorization of the multi-antenna periodogram, namely

[0074]

no. 2 example

[0076] In the second embodiment of the present invention, MMSE pre-equalization can be divided into two stages: first temporal pre-equalization (9, 11), and then spatial decorrelation (10, 12). See Figures 4a and 4b for two alternative embodiments of this spatial and temporal pre-equalization.

[0077] In the first stage, for the number of antennas α, temporal pre-equalization (11) employs frequency-domain filter coefficients

[0078]

[0079] carry out, where is a scalar spectral shaping filter (SSF), such as a raised cosine filter, and is the frequency and block number A single-antenna periodogram. Notice, is real-valued and positive, which simplifies square root and division calculations.

[0080] For the number of antennas α, the periodogram can be estimated as a moving average

[0081]

[0082] in, is the appropriate scaling factor, e.g. . Alternatively, estimate the periodogram recursively,

[0083]

[0084] in, is an appropriate forgetting f...

no. 3 example

[0102] In a third embodiment of the invention, the frequency domain spatial decorrelation as described in the second stage of the previous subsection is performed in the time domain (10). For an illustration of this spatial and temporal pre-equalization, see Figure 5 .

[0103] At the first level, temporal pre-equalization (11) is performed as in the previous node, i.e. as an element-wise scalar multiplication

[0104]

[0105] For each antenna α, frequency index and blocks ,in

[0106]

[0107] The time-domain form of the time-pre-equalized signal of antenna α is expressed as

[0108]

[0109] By using an "overlap and add" approach such as Figure 7 As shown, a new time domain sequence is constructed. This is determined by each antenna α is represented by and the runtime index is continuous sequence of . In vector representation, time The temporally pre-equalized signal is expressed as

[0110]

[0111] In the second stage, time domain spatial decor...

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Abstract

The present invention describes a channel equalizer and a method for channel equalization in a receiver in a multi-user communication system. The method comprises the steps of receiving a signal with at least two antennas to produce at least two antenna input streams, measuring the temporal of each antenna input stream and the spatial correlation between the antenna input streams, determining a user-independent pre-equalization filter from the temporal and spatial correlation, filtering the antenna input streams with the pre-equalization filter, and finally inputting the filtered signal to a user-dependent receiver configured to detect the received data symbols of a given user.

Description

technical field [0001] The present invention relates to channel equalization methods used in multi-user communication systems. Although the present invention relates specifically to WCDMA communication systems, it should be noted that it is applicable to other communication systems, including LTE, WiMAX, WiFi, UWB, GSM, etc. The present invention is a low-complexity user-independent spatial and temporal minimum mean square error (MMSE) pre-equalization. Background technique [0002] In any wireless communication system, the transmitted signal is distorted by the dynamic nature of the wireless channel. These dynamic properties give rise to frequency selective channels. Therefore, at the receiver side, some equalization scheme can be applied in order to compensate for the dynamic characteristics of the wireless channel. Ideal compensation removes the effects of the radio channel and makes the resulting equalized channel perfectly frequency flat. However, this approach caus...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B7/08H04L1/06
CPCH04B1/7115H04L25/03133H04L25/03159
Inventor H.萨林B.U.A.西尔博姆
Owner TELEFON AB LM ERICSSON (PUBL)
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