TW200529578A - A W-CDMA equalized rake receiver - Google Patents

Abstract

A Wideband Code Division Multiple Access (W-CDMA) system, also known as the 3G system, deploys the RAKE receiver at both the Base Station (BS) and Mobile Station (MS) to increase the signal-to-noise ratio (SNR). A conventional RAKE receiver delays the received signal and multiplies each finger with a complex weight to form a coherent output. Since RAKE receiver can fully exploit the path diversity property, therefore, RAKE receiver can increase system performance if each path can be well separated. Consider that if two or more signals from different paths arrived at the receiver within a chip time, RAKE receiver will fail to separate individual paths because the time difference of two successive resolvable paths should be greater than a chip time. This phenomenon leads to the inter-chip-interference (ICI) problem for the W-CDMA system. Many methods, such as an equalizer can be used to minimize the ICI of the received signal. However, if the equalizer contains R taps in a tapped delay line, RTs must be long enough to capture the delay profile of the channel, where Ts is the sampling period. Hence, the equalizer will need very long taps and complicated hardware and it will be very computationally intensive. Another method, the spatial filtering RAKE receiver, can be used to filter the desired and undesired signals within a chip time. But it needs an antenna array to form a main beam to the desired one and suppress the undesired. In addition, if the angles of arrivals (AOA) of the desired and undesired are very close, performance of the spatial filtering RAKE receiver will be poor. Therefore, taking the practical constrains into considerations, a conventional RAKE receiver requires some modifications. This invention proposes a modified RAKE receiver, an equalized RAKE receiver to solve the ICI problem. The proposed equalized RAKE receiver can reduce the ICI degradation with simple hardware complexity. The proposed equalized RAKE receiver uses the spread pilot symbols of the dedicated physical control channel to estimate the required weightings of the equalizer on each finger. Once the weightings be estimated according to some algorithms, such as the minimum mean square error (MMSE) algorithm or the zero forcing (ZF) method, the ICI interference on each finger can be compensated with a reasonable hardware complexity.

Description

200529578 (1) Description of the invention: [Technical field to which the invention belongs] The present invention can be used for a receiver of a base station and a mobile station of a wideband multiplexing system (W-CDMA). [Previous Technology] The Equalizer receiver method or Antenna array is used to solve the problem of mutual interference of the expansion elements. [Summary of the invention] The equalized rake receiver mentioned in the present invention is a complex gain operation of the traditional rake receiver, which is replaced by an equalizer. Since only one receiving antenna is needed to receive a unit of expansion time. The signals are processed. Therefore, the hardware complexity is greatly reduced compared to the equalized reception 1§ and the antenna array, and the function of suppressing the mutual interference of the expansion elements is maintained. [Implementation method] Step 1: Use the matched filter of the dedicated entity control channel of the multiplexing system to estimate the signal arrival time (Time 〇f Anival, TOA) of the receiving signal path (Finger), and send the result to Weight generator. Step two: The weight generator uses the received signal and the estimated signal of the physical control channel to calculate the equalized weight of each signal path in an unfolded unit time. Step 2: Use the estimated equalization weights to compensate the reception signal of the dedicated physical data channel. Step 4: Use a multiplier to receive the compensated physical data channel for de-spread operation. Step 5: Sum the un-spread signals of each received signal path and estimate the data transmitted by the transmitter. [Schematic description] 7 200529578 As shown in Figure 1, the present invention uses a receiving antenna to separate the dedicated physical control channel (DPCCH) and dedicated physical data channel (DPDCH) of each other's true fathers in a code division multiplexing system. For processing, the Ricoh belongs to the entity control channel matching listening to the arrival date of the pure observation number, and uses the value generator to calculate the value of each signal path in an unfolded unit time. The receiving signal of the material channel and inverse = (de_spread) operation to determine the data transmitted by the transmitter. Respect

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Claims (1)

200529578 Scope of patent application: Yima Xigong system receiving device, which replaces the traditional rake type receiver with an equalizer and adds ^ the estimated signal of the control channel to calculate each signal path in an unfolding block. Weight of equalizer in unit time. 3. It can be the decision criterion of any wire feeder. For example, the method of Mlmmum Mean E ^ F = ng can be used to determine the weights of the feeder. The square error method has better results. J Huaping 9