Acquisition method and apparatus for carrying out the method

• US 20010030994A1
• Filed: 01/22/2001
• Published: 10/18/2001
• Est. Priority Date: 07/21/1998
• Status: Active Grant

• Current Assignee: Intel Deutschland GmbH (Intel Corporation)
• Original Assignee: Infineon Technologies AG
• Inventors: Gunzelmann, Bertram, Molev-Shteiman, Arkadi
• Granted Patent: US 7,133,438 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7095 Sliding correlator type

Abstract

An acquisition method for identifying a transmitter, and a correlator for carrying out the method includes correlating a received binary-coded spread sequence having m bits at a frequency f with a locally generated spread sequence by phase-shifting a multiplicity of locally generated spread sequences with respect to the received spread sequence, where f is the frequency of the incoming spread sequence. The received spread sequence is correlated with a locally generated spread sequence at the frequency f. The received spread sequence is stored and the stored, received spread sequence is processed at an oversampling rate i*f. The received, stored spread sequence is split into i sections and the correlation is carried out in i steps. The correlator includes a shift register with feedback. Register positions of the shift register are connected in parallel to a memory input, and the memory output is connected in parallel with the register positions. A further memory holds reference signal sequences and a comparator compares the memory content with further memory content.

Claims

1. A communications acquisition method, which comprises:

correlating a binary-coded spread sequence arriving at a frequency f and having m bits with a locally generated spread sequence by phase-shifting a multiplicity of locally generated spread sequences with respect to the received spread sequence;

correlating the received spread sequence with a locally generated spread sequence at the frequency f;

storing the received spread sequence and processing the stored, received spread sequence at an oversampling rate of i*f, where i is an integer; and

splitting the stored, received spread sequence into i sections and carrying out the correlation in i steps.

2. The method according to

claim 1

, which further comprises:

shifting the received spread sequence bit by bit within k cycles in k section variants each having m bits at an oversampling rate of k*f, where k is an integer, by shifting a most significant bit of a section variant to a position of a least significant bit of a succeeding section variant;

after k cycles, replacing the least significant bit by a succeeding bit of the received spread sequence and repeating the shifting and replacing steps m−

1) times;

subdividing the locally generated spread sequence into k sections each having n bits, where n is an integer, and comparing each of these sections with a section variant of the received spread sequence within a cycle;

counting all matches and storing the count results; and

carrying out a maximum search over all the count results.

3. The method according to

claim 2

, wherein a number of sections of prescribed length is k=32 and a chip length of the sections is n=32.

4. A correlator for performing a communications acquisition, comprising:

a FIFO memory having a memory input and a memory output, said FIFO memory inputting and outputting content;

a shift register with feedback for holding a received signal sequence in serial form, said shift register being clocked at an oversampling rate and having register positions connected in parallel to said memory input for parallel storage of a plurality of shift register contents read out in succession, said memory output being connected in parallel with said register positions for parallel transfer of data to said shift register;

a further memory for holding reference signal sequences; and

a comparator for comparing the content of said FIFO memory with a content of said further memory at said oversampling rate;

the correlator programmed to perform the steps of;

correlating a binary-coded spread sequence arriving at a frequency f and having m bits with a locally generated spread sequence by phase-shifting a multiplicity of locally generated spread sequences with respect to the received spread sequence;

correlating the received spread sequence with a locally generated spread sequence at said frequency f;

storing the received spread sequence and processing the stored, received spread sequence at said oversampling rate equal to i*f, where i is an integer; and

splitting the stored, received spread sequence into i sections and carrying out the correlation in i steps.

5. The correlator according to

claim 4

, wherein said comparator has a comparator output, and including an adder comprising two-bit adders configured to form a cascaded interconnection, each of said two-bit adders having at least two inputs and an output, said output of each of said two-bit adders connected to one of said at least two inputs of a succeeding one of said two-bit adders, said adder connected to said comparator output and configured to add up logic values produced during bit-by-bit comparison for matching bit positions.