FFT-based method for capturing PN sequence in CDMA 2000 1x EV-DO system

A cdma2000lxev-do and sequence capture technology, applied in transmission systems, multi-frequency code systems, electrical components, etc., can solve the problems of large amount of calculation, inability to guarantee capture performance, and long search time, so as to reduce the amount of calculation and realize Effects of Phase Capture, Reliable Phase Capture

Inactive Publication Date: 2012-09-05
COMBA TELECOM SYST CHINA LTD
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Problems solved by technology

[0027] For the traditional acquisition method, there are two main defects: on the one hand, 16 kinds of PN patterns need to be detected separately, the calculation amount is large, and the required search time is too long; on the other hand, the E c / N 0 (E c is the average chip energy of the received signal, N 0 In the case of low noise power spectral density) and large frequency offset, the capture performance cannot be guaranteed

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  • FFT-based method for capturing PN sequence in CDMA 2000 1x EV-DO system
  • FFT-based method for capturing PN sequence in CDMA 2000 1x EV-DO system
  • FFT-based method for capturing PN sequence in CDMA 2000 1x EV-DO system

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[0051] The present invention can be realized on the programmable device, and the process of carrying out correlation calculation on the received signal is as follows: Figure 6 As shown, the whole capture process is as follows Figure 7 Shown; specifically include the following steps:

[0052] Step 1. Use the time s as the starting position of the current search window, buffer the received signal with a length of M chips; divide the received signal into L accumulation windows, each accumulation window contains N chips, and accumulate two adjacent The starting position of the window is 1024 chips apart, and the time s is the starting position of the first accumulation window, M=1024 (L-1)+N, N is the number of FFT / IFFT transformation points and the value is 2 integer power.

[0053] Denote the received signal as r(s+k), r(s+k)=r I (s+k)+j·r Q (s+k), k=0, 1, 2...M-1. Let i=0, i represents the local PN pattern number, 0≤i≤15. When N>1024, the received signals of two adjacen...

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Abstract

The invention relates to a FFT-based method for capturing a PN sequence in a CDMA 2000 1x EV-DO system, which comprises the main steps that: a receiving signal with the length of M chips is divided into L accumulation windows respectively containing N chips; initial positions between two adjacent accumulation windows are away from 1,024 chips; the jth interception of a local PN sequence of which the PN pattern number is i is zeroized to an N point for the complex FFT transform, transformed results are subjected to conjugation, and then the conjugated results are multiplied with the results after the complex FFT transform of accumulation window data point by point; the multiplied results are subjected to IFFT transform, and the first N-96 points are taken for module-square evaluation to obtain a related result of the PN pattern of which the number is i corresponding to the j accumulation window; and the steps are repeated to acquire the related results of the 16 PN patterns, and the related results are accumulated respectively to judge whether the accumulation results exceed a preset threshold or not. The FFT-based method can search the 16 PN patterns parallelly, and shorten capturing time; and the capturing performance is not influenced by the lower EX / N0 of the receiving signal and frequency offset.

Description

technical field [0001] The invention relates to a method for capturing PN sequences in a spread spectrum communication system, in particular to a method for realizing downlink synchronous PN sequence capturing in a CDMA2000 1x EV-DO (EV-DO for short) system. Background technique [0002] CDMA2000 1x is one of the 3G cellular wireless mobile communication systems widely used in commercial use. However, with the continuous growth of wireless data service requirements, the ability of CDMA2000 1x to support high-speed packet data services cannot meet the needs of future development. For this reason, 3GPP2 proposed the EV-DO (Evolution Data Optimized) technology, which is specially designed for the burstiness of data services, the asymmetry of forward / reverse link load and the characteristics of large channel capacity, and provides more High data transmission capacity. [0003] Compared with CDMA2000 1x system, EV-DO can provide higher air interface rate. The forward link uses ...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26H04B1/7075
Inventor 高原许鸿辉施英
Owner COMBA TELECOM SYST CHINA LTD
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