Reception of multiple code length CDMA transmissions

• US 7,522,656 B2
• Filed: 03/16/2005
• Issued: 04/21/2009
• Est. Priority Date: 03/16/2005
• Status: Active Grant

• Current Assignee: France Brevets SAS
• Original Assignee: Nokia Corporation
• Inventors: Turunen, Seppo, Zhengdi, Qin
• Primary Examiner(s): Ahn; Sam K
• Application Number:
  US11/091,360
• Publication Number:
  US 20060209934A1
• Time in Patent Office: 1,497 Days
• Field of Search: 375/142, 375/143, 375/150, 375/152, 375/343, 704/216, 704/218, 704/237, 704/263, 708/5, 708/422, 708/813, 342/108, 342/145, 342/189, 342/378
• US Class Current: 375/150
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates

Abstract

Code synchronization is acquired as a part of receiving and decoding a spread spectrum transmission. There are received a number of signal samples that constitute a signal sample sequence. It represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code. The signal sample sequence is augmented at least at one end with at least one additional symbol, which produces a padded signal sample sequence. The padded signal sample sequence is in turn correlated with a locally produced sample sequence that comprises code samples representing a known form of said spreading code. The result of said correlating is used as a basis for acquired code synchronization.

Claims

1. A method for determining code synchronization timing in relation to a spread spectrum transmission, comprising:

receiving a number of signal samples, said number of signal samples constituting a signal sample sequence that represents a length of a received signal spread with a pseudorandom sequence used as a spreading code, said pseudorandom sequence having a length,

as a response to the length of said pseudorandom sequence being different than a dimension of a piece of code acquisition means, processing said signal sample sequence, thus producing a processed signal sample sequence,

correlating said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, thus producing a correlation, and

using a result of said correlation as a basis for determining a code synchronization wherein said locally produced sample sequence contains as many code samples as there are signal samples in the signal sample sequence before said processing, wherein processing said signal sample sequence involves augmenting said signal sample sequence at least at one end with at least one additional symbol, thus producing a padded signal sample sequence, and said locally produced sample sequence contains additionally neutral symbols used to fill in said locally produced sample sequence to a length that is equal to the length of said padded signal sample sequence, and wherein said additional symbols used to augment said signal sample sequence at least at one end are signal samples from another signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code.

2. A method, comprising:

receiving a number of signal samples, said number of signal samples constituting a signal sample sequence that represents a length of a received signal spread with a pseudorandom sequence used as a spreading code, said pseudorandom sequence having a length,

as a response to the length of said pseudorandom sequence being different than a dimension of a piece of code acquisition hardware, processing said signal sample sequence, thus producing a processed signal sample sequence,

correlating said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, thus producing a correlation, and

using a result of said correlation as a basis for determining a code synchronization;

wherein said locally produced sample sequence contains as many code samples as there are signal samples in the signal sample sequence before said processing, and wherein processing said signal sample sequence involves augmenting said signal sample sequence at least at one end with at least one additional symbol, and wherein said additional symbols used to augment said signal sample sequence at least at one end are signal samples from another signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code.

3. A method for determining code synchronization timing in relation to a spread spectrum transmission, comprising:

receiving a number of signal samples, said number of signal samples constituting a signal sample sequence that represents a length of a received signal spread with a pseudorandom sequence used as a spreading code, said pseudorandom sequence having a length,

as a response to the length of said pseudorandom sequence being different than a dimension of a piece of code acquisition means, processing said signal sample sequence, thus producing a processed signal sample sequence,

correlating said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, thus producing a correlation, and

using a result of said correlation as a basis for determining a code synchronization, wherein said locally produced sample sequence contains;

a continuous sequence of code samples representing a known form of a full length of said spreading code, and

a number of additional code samples obtained as a cyclic continuation of said continuous sequence of code samples from an opposite extremity thereof.

4. A method for determining code synchronization timing in relation to a spread spectrum transmission, comprising:

receiving a number of signal samples, said number of signal samples constituting a signal sample sequence that represents a length of a received signal spread with a pseudorandom sequence used as a spreading code, said pseudorandom sequence having a length,

as a response to the length of said pseudorandom sequence being different than a dimension of a piece of code acquisition means, processing said signal sample sequence, thus producing a processed signal sample sequence,

correlating said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, thus producing a correlation, and

using a result of said correlation as a basis for determining a code synchronization

receiving information about the length of a spreading code that has been used to spread the received signal,

comparing said length of a spreading code to a dimension of a piece of code acquisition hardware,

if said comparison shows said length of a spreading code to be smaller than said dimension of said piece of code acquisition hardware, augmenting the received signal sample sequence at least at one end with at least one additional symbol, thus producing a padded signal sample sequence, correlating said padded signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, and using a result of said correlating as a basis for determining code synchronization,

if said comparison shows said length of a spreading code to equal said dimension of said piece of code acquisition hardware, correlating a received signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, and using a result of said correlating as a basis for determining code synchronization, and

if said comparison shows said length of a spreading code to be larger than said dimension of code acquisition hardware, truncating a received signal sample sequence at least at one end, thus obtaining a truncated signal sample sequence, and correlating said truncated signal sample sequence with a truncated locally produced sample sequence that comprises a subset of a full number of code samples representing a known form of said spreading code, and using a result of said correlating as a basis for determining code synchronization.

5. A device, comprising:

a piece of code acquisition hardware adapted to receive a signal sample sequence that represents a received signal spread with a pseudorandom sequence used as a spreading code, which pseudorandom sequence has a length;

wherein said piece of code acquisition hardware is adapted to respond to the length of said pseudorandom sequence being different than a dimension of said piece of code acquisition hardware by processing said signal sample sequence to produce a processed signal sample sequence, and said piece of code acquisition hardware is also adapted to correlate said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, and wherein the receiver device is adapted to use a result of said correlating as a basis for determining code synchronization, wherein said piece of code acquisition hardware is configured to augment said signal sample sequence at least at one end with at least one additional symbol to produce a padded signal sample sequence to be used as said processed signal sequence, and wherein said piece of code acquisition hardware is configured to use as said additional symbols signal samples from another signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code.

6. A device according to claim 5, wherein said piece of code acquisition hardware comprises a matched filter adapted to receive a fixed number of signal samples for correlation with a locally produced code sample sequence, which fixed number is equal to the number of samples in said signal sample sequence and the number of said additional symbols taken together.

7. A device according to claim 5, comprising a reception and baseband conversion block adapted to receive a spread spectrum transmission and to convert it into signal samples on a baseband frequency.

8. A device according to claim 5, wherein the receiver device is a satellite positioning receiver.

9. A device for receiving and decoding a spread spectrum transmission, comprising:

a piece of code acquisition hardware adapted to receive a signal sample sequence that represents a received signal spread with a pseudorandom sequence used as a spreading code, which pseudorandom sequence has a length;

wherein said piece of code acquisition hardware is adapted to respond to the length of said pseudorandom sequence being different than a dimension of said piece of code acquisition hardware by processing said signal sample sequence to produce a processed signal sample sequence, and said piece of code acquisition hardware is also adapted to correlate said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, and wherein the receiver device is adapted to use a result of said correlating as a basis for determining code synchronization, comprising a reception control block adapted to derive a length of said spreading code from information received on a pilot channel, which reception control block is further adapted to deliver said length of said spreading code for use in said piece of code acquisition hardware.

10. A signal processing module for performing code acquisition in receiving and decoding spread spectrum transmissions, comprising a piece of code acquisition hardware adapted to receive a signal sample sequence that represents a received signal spread with a pseudorandom sequence used as a spreading code, which pseudorandom sequence has a length, wherein said piece of code acquisition hardware is adapted to respond to the length of said pseudorandom sequence being different than a dimension of said piece of code acquisition hardware by processing said signal sample sequence to produce a processed signal sample sequence, and said piece of code acquisition hardware is also adapted to correlate said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, wherein said piece of code acquisition hardware is configured to augment said signal sample sequence at least at one end with at least one additional symbol to produce a padded signal sample sequence to be used as said processed signal sequence, and wherein said piece of code acquisition hardware is configured to use as said additional symbols signal samples from another signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code.

11. A signal processing module for performing code acquisition in receiving and decoding spread spectrum transmissions, comprising a piece of code acquisition hardware adapted to receive a signal sample sequence that represents a received signal spread with a pseudorandom sequence used as a spreading code, which pseudorandom sequence has a length, wherein said piece of code acquisition hardware is adapted to respond to the length of said pseudorandom sequence being different than a dimension of said piece of code acquisition hardware by processing said signal sample sequence to produce a processed signal sample sequence, and said piece of code acquisition hardware is also adapted to correlate said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, comprising a first piece of code acquisition hardware and a second piece of code acquisition hardware, of which said first piece of code acquisition hardware is adapted to receive a signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence having a first length, and said second piece of code acquisition hardware is adapted to receive a signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence having a second length different than said first length, and said signal processing module is adapted to select for use that of said first piece of code acquisition hardware and said second piece of code acquisition hardware for which the corresponding length of pseudorandom sequence is closer to the length of a pseudorandom sequence used for spreading a signal that has been received.

12. A system for communicating with spread spectrum signals, comprising:

a first transmitter adapted to use a first pseudorandom sequence for producing spread spectrum transmissions,

a second transmitter adapted to use a second pseudorandom sequence for producing spread spectrum transmissions, said second pseudorandom sequence being shorter in length than said first pseudorandom sequence,

a receiver adapted to receive spread spectrum transmissions from both said first transmitter and said second transmitter,

in said receiver a piece of code acquisition hardware adapted to receive a signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code;

wherein said piece of code acquisition hardware is adapted to respond to the length of said pseudorandom sequence used as a spreading code being different than a dimension of said piece of code acquisition hardware by processing said signal sample sequence to produce a processed signal sample sequence, and said piece of code acquisition hardware is also adapted to correlate said processed signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code, and wherein the receiver device is adapted to use a result of said correlating as a basis for determining a code synchronization.

13. A code acquisition module having embodied therein a computer program for controlling code acquisition in a receiver adapted to receive and decode spread spectrum transmissions, said computer program comprising:

computer code adapted to drive a piece of code acquisition hardware to augmenting a signal sample sequence at least at one end with at least one additional symbol, thus producing a padded signal sample sequence, and

computer code adapted to drive said piece of code acquisition hardware to correlating said padded signal sample sequence with a locally produced sample sequence that comprises code samples representing a known form of said spreading code,

wherein said locally produced sample sequence contains as many code samples as there are signal samples in the signal sample sequence before said processing, and wherein processing said signal sample sequence involves augmenting said signal sample sequence at least at one end with a least one additional symbol, and wherein said at least one additional symbol used to augment said signal sample sequence at least at one end comprise one or more signal samples from another signal sample sequence that represents a length of a received signal spread with one full length of a pseudorandom sequence used as a spreading code.