Method, apparatus, and computer product for generating an SC-FDMA signal

• US 8,315,148 B2
• Filed: 12/22/2009
• Issued: 11/20/2012
• Est. Priority Date: 12/23/2008
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Lipka, Dietmar, Mueller-Weinfurtner, Stefan
• Primary Examiner(s): Riyami, Abdullah
• Application Number:
  US12/644,761
• Publication Number:
  US 20100195479A1
• Time in Patent Office: 1,064 Days
• Field of Search: 370/203, 370/206, 370/208, 370/281, 370/480, 375/260
• US Class Current: 370/203
• CPC Class Codes: H04J 13/0059 CAZAC [constant-amplitude and zero auto-correlation]
• CPC Class Codes: H04J 13/14 Generation of codes with a zero correlation zone
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2684 Complexity

Abstract

A technique for generating a Single-Carrier Frequency Division Multiple Access (SC-FDMA) signal based on a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence is disclosed. A method embodiment of this technique comprises generating a frequency domain representation of the CAZAC sequence by providing an analytical representation of the CAZAC sequence in the frequency domain with an integer phase term and calculating the integer phase term in a recursive manner for each of a plurality of frequency domain samples of the CAZAC sequence. The resulting frequency domain representation of the CAZAC sequence is then mapped to a pre-determined frequency location before being transformed into the time domain to obtain a time domain representation of the SC-FDMA signal. The SC-FDMA signal may be a random access signal for transmission on a Physical Random Access Channel (PRACH).

Claims

1. A method of generating a Single-Carrier Frequency Division Multiple Access, or SC-FDMA, signal based on a given Constant Amplitude Zero Auto-Correlation, or CAZAC, sequence, the method comprising:

generating a frequency domain representation of the CAZAC sequence, comprising;

providing an analytical representation of the CAZAC sequence in the frequency domain with an integer phase term; and

calculating the integer phase term in a recursive manner for each of a plurality of frequency domain samples of the CAZAC sequence;

mapping the resulting frequency domain representation of the CAZAC sequence to a pre-determined frequency location; and

transforming the mapped frequency domain representation into the time domain to obtain a time domain representation of the SC-FDMA signal.

2. The method of claim 1, wherein the analytical representation X [k] of the CAZAC sequence has essentially the form of

3. The method of claim 1, wherein the integer phase term p[k] has essentially the form of

p[k]=C_vk+2⁻

1u<sup>−

1</sup>·

k(k+u),

C_v, u being parameters uniquely identifying the given CAZAC sequence, and

k being a frequency domain counting parameter.

4. The method of claim 1, wherein generating the frequency domain representation of the CAZAC sequence further comprises determining an individual frequency domain sample of the CAZAC sequence based on the integer phase term calculated for this sample.

5. The method of claim 4, wherein determining the frequency domain sample comprises at least one table look-up operation using the integer phase term calculated for this sample as an input parameter.

6. The method of claim 1, wherein the recursive calculation includes a modulo operation to limit an integer range of the integer phase term.

7. The method of claim 1, wherein the integer phase term is calculated using two nested recursions.

8. The method of claim 7, wherein the two nested recursions are defined as:

p[k]=(p[k−

1]+q[k])mod N_ZC and

q[k]=(q[k−

1]+u<sup>−

1</sup>)mod N_ZC,

p(k) being the integer phase term,

q[k] an intermediate variable of the two nested recursions,

k being a frequency domain counting parameter,

u being a parameter identifying the given CAZAC sequence, and

N_ZC being an integer value indicative of a length of the given CAZAC sequence.

9. The method of claim 8, wherein initialization values of the two nested recursions are selected as:

p[0]=0 and

q[0]=(C_v+2<sup>−

1</sup>u<sup>−

1</sup>·

(u−

1))mod N_ZC,

C_v being a parameter identifying the given CAZAC sequence.

10. The method of claim 1, wherein the CAZAC sequence is a Zadoff-Chu sequence.

11. The method of claim 1, wherein the CAZAC sequence comprises N samples, with N being a prime number.

12. The method of claim 1, wherein the SC-FDMA signal is a random access signal, and further comprising transmitting the random access signal on a physical random access channel that belongs to a mobile communications network supporting SC-FDMA.

13. A computer program product stored on a non-transitory computer-readable recording medium for performing the steps of claim 1 when executed by a processor.

14. An apparatus for generating a Single-Carrier Frequency Division Multiple Access, or SC-FDMA, signal based on a given Constant Amplitude Zero Auto-Correlation, or CAZAC, sequence, the device comprising:

a generator configured to generate a frequency domain representation of the CAZAC sequence based on an analytical representation of the CAZAC sequence in the frequency domain with an integer phase term, wherein the generator calculates the integer phase term in a recursive manner for each of a plurality of frequency domain samples of the CAZAC sequence;

a mapper configured to map the resulting frequency domain representation of the CAZAC sequence to a pre-determined frequency location; and

a transformator configured to transform the mapped frequency domain representation into the time domain to obtain a time domain representation of the SC-FDMA signal.

15. The apparatus of claim 14, further comprising a storage with a look-up table, wherein the generator is configured to determine an individual frequency domain sample of the CAZAC sequence based on the integer phase term calculated for this sample by accessing the look-up table using the integer phase term as an input parameter.

16. A user terminal comprising the apparatus of claim 14, the user terminal being configured to support SC-FDMA.