Compression of baseband signals in base transceiver system radio units

• US 8,331,461 B2
• Filed: 09/23/2011
• Issued: 12/11/2012
• Est. Priority Date: 05/21/2008
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Wegener, Albert W.
• Primary Examiner(s): PATEL, DHAVAL V
• Application Number:
  US13/243,154
• Publication Number:
  US 20120014422A1
• Time in Patent Office: 445 Days
• Field of Search: 375/140, 375/150, 375/240, 375/256, 375/260, 375/267, 375/340, 375/341, 341/51, 382/166
• US Class Current: 375/241
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A signal compression method and apparatus for a base transceiver system (BTS) in a wireless communication network provides efficient transfer of compressed signal samples over serial data links in the system. For the uplink, an RF unit of the BTS compresses baseband signal samples resulting from analog to digital conversion of a received analog signal followed by digital downconversion. The compressed signal samples are transferred over the serial data link to the baseband processor then decompressed prior to normal signal processing. For the downlink, the baseband processor compresses baseband signal samples and transfers the compressed signal samples to the RF unit. The RF unit decompresses the compressed samples prior to digital upconversion and digital to analog conversion to form an analog signal for transmission over an antenna. Compression and decompression can be incorporated into operations of conventional base stations and distributed antenna systems, including OBSAI or CPRI compliant systems.

Claims

1. A radio for transmitting and receiving an RF signal including a plurality of antenna-carrier channels, comprising:

an interface for a bi-directional serial data channel carrying serial data streams including corresponding incoming and outgoing sequences of data structures, at least some of the data structures in the sequence holding compressed in-phase (I) and quadrature (Q) signal samples for a plurality of baseband antenna-carrier channels of a wireless communication network;

logic coupled to assemble the outgoing sequences of data structures from a plurality of sequences of compressed I and Q signal samples corresponding to the plurality of baseband antenna-carrier channels, and to disassemble the incoming sequences of data structures, to recover a plurality of sequences of compressed I and Q signal samples corresponding to the plurality of baseband antenna-carrier channels; and

compression and decompression logic arranged to compress I and Q signal samples of the plurality of baseband antenna-carrier channels to provide the outgoing sequences of compressed I and Q signal samples, and arranged to decompress the incoming sequences of compressed I and Q signal samples to provide decompressed I and Q signal samples of the plurality of baseband antenna-carrier channels;

an upconverter arranged to upconvert the incoming sequences of decompressed I and Q signal samples for the respective baseband antenna-carrier channels to form digital samples of a plurality of antenna-carrier channels;

a downconverter arranged to downconvert digital samples of a received RF signal to produce I and Q signal samples of the plurality of baseband antenna-carrier channels; and

a transducer arranged to convert the digital samples of the plurality of antenna-carrier channels to an analog RF signal, and to convert the received analog RF signal to the digital samples of antenna-carrier channels.

2. The radio of claim 1, including one or more antennas coupled to the transducer.

3. The radio of claim 1, wherein the compression and decompression logic is configured in response to one or more compression control parameter(s) based on one or more characteristics of the signal samples.

4. The radio of claim 3, wherein said data structures include a header, the header including the one or more compression control parameters.

5. The radio of claim 3, wherein said data structures carry the one or more compression control parameters.

6. The radio of claim 3, wherein the one or more characteristics include(s) at least one of an oversampling ratio, a bandwidth, a modulation type, and an air interface of the signal samples.

7. The radio of claim 1, wherein data structures in at least one of said incoming sequences of data structures include containers assembled from more than one set of containers in a plurality of sets of containers, each set of containers in the plurality including compressed I and Q signal samples of a corresponding baseband antenna-carrier channel, containers that are members of the set of containers for a given antenna-carrier channel including a corresponding block of compressed signal samples from the compressed I and Q signal samples for the given baseband antenna-carrier channel, and

said logic to disassemble the data structures parses the data structures to derive said plurality of sets of containers, and produces the corresponding sequences of compressed I and Q signal samples.

8. The radio of claim 1, wherein one of said incoming data structures includes a plurality of messages carrying payload derived from packets comprising compressed I and Q signal samples of the plurality of baseband antenna-carrier channels.

9. The radio of claim 1, wherein data structures in at least one of said incoming and outgoing sequences of data structures include containers assembled from more than one set of containers in a plurality of sets of containers, each set of containers in the plurality including compressed I and Q signal samples of a corresponding baseband antenna-carrier channel, containers that are members of the set of containers for a given baseband antenna-carrier channel including a corresponding block of compressed signal samples from the compressed I and Q signal samples for the given baseband antenna-carrier channel, and

said logic to assemble the data structures forms a plurality of sets of containers, each set of containers in the plurality including compressed signal samples of a corresponding baseband antenna-carrier channel, containers that are members of the set of containers for a given baseband antenna-carrier channel including a corresponding block of compressed signal samples from the compressed I and Q signal samples for the given antenna-carrier channel, and assembles containers from the plurality of sets of containers into said data structures, at least some of the data structures including containers assembled from more than one of the sets of containers in the plurality of sets of containers.

10. The radio of claim 1, wherein one of said outgoing data structures includes a plurality of messages carrying payload derived from packets comprising compressed I and Q signal samples of the plurality of baseband antenna-carrier channels, and said logic to assemble the data structure that forms a frame including a packet comprising compressed I and Q signal samples of a plurality of baseband antenna-carrier channels divides the frame into a plurality of messages, and interleaves the plurality of messages to form said data structures.

11. The radio of claim 1, wherein the logic to assemble the outgoing sequences of data structures and the logic to disassemble incoming sequences of data structures operates in compliance with a Common Public Radio Interface (CPRI) standard.

12. The radio of claim 1, wherein the logic to assemble the outgoing sequences of data structures and the logic to disassemble incoming sequences of data structures operates in compliance with an Open Base Station Architecture Initiative (OBSAI) standard.

13. A method, comprising:

sampling and downconverting an RF signal including a plurality of antenna-carrier channels to generate a plurality of sequences of in-phase (I) and quadrature (Q) signal samples representing a plurality of baseband antenna-carrier channels of a wireless communication network;

compressing the plurality of sequences of I and Q signal samples to form compressed I and Q signal samples for the plurality of baseband antenna-carrier channels;

combining the compressed I and Q signal samples for the plurality of baseband antenna-carrier channels into data structures for a serial data stream; and

transmitting data structures for a serial data stream on a serial data link.

14. The method of claim 13, wherein said sampling includes oversampling.

15. The method of claim 13, including applying one or more compression control parameters based on one or more characteristics of the signal samples to said compressing.

16. The method of claim 15, wherein said data structures include a header, the header including the one or more compression control parameters.

17. The method of claim 15, wherein said data structures carry the one or more compression control parameters.

18. The method of claim 15, wherein the one or more characteristics include(s) at least one of an oversampling ratio, a bandwidth, a modulation type, and an air interface of the signal samples.

19. The method of claim 13, wherein said combining includes

forming a plurality of sets of containers, each set of containers in the plurality including compressed signal samples of a corresponding baseband antenna-carrier channel, containers that are members of the set of containers for a given baseband antenna-carrier channel including a corresponding block of signal samples from the compressed I and Q signal samples for the given baseband antenna-carrier channel;

and

assembling containers from the plurality of sets of containers into the data structures, at least some of the data structures including containers assembled from more than one of the sets of containers in the plurality of sets of containers.

20. The method of claim 13, wherein said combining includes

forming a frame including a packet comprising compressed I and Q signal samples of one of the plurality of baseband antenna-carrier channels;

dividing the frame into a plurality of messages; and

interleaving the plurality of messages to form said data structures.

21. The method of claim 13, wherein the step of combining is performed in accordance with a Common Public Radio Interface (CPRI) standard.

22. The method of claim 13, wherein the step of combining is performed in accordance with an Open Base Station Architecture Initiative (OBSAI) standard.

23. A method, comprising:

receiving, on a serial data link, a serial data stream including a sequence of data structures, at least some of the data structures in the sequence holding compressed in-phase (I) and quadrature (Q) signal samples for a plurality of baseband antenna-carrier channels of a wireless communication network for a plurality of subscriber signals;

disassembling the sequence of data structures to recover a plurality of sequences of compressed I and Q signal samples corresponding to the plurality of baseband antenna-carrier channels;

decompressing the recovered plurality of sequences of compressed I and Q signal samples to form sequences of I and Q signal samples for respective baseband antenna-carrier channels of the plurality of baseband antenna-carrier channels;

upconverting the sequences of I and Q signal samples for the respective baseband antenna-carrier channels to form digital samples of a plurality of antenna-carrier channels; and

transducing the digital samples of the plurality of antenna-carrier channels to an RF signal carrying the plurality of subscriber signals.

24. The method of claim 23, including applying one or more compression control parameters based on one or more characteristics of the signal samples to said decompressing.

25. The method of claim 24, wherein said data structures include a header, the header including the one or more compression control parameters.

26. The method of claim 24, wherein said data structures carry the one or more compression control parameters.

27. The method of claim 24, wherein the one or more characteristics include(s) at least one of an oversampling ratio, a bandwidth, a modulation type, and an air interface of the signal samples.

28. The method of claim 23, wherein said data structures include containers assembled from more than one set of containers in a plurality of sets of containers, each set of containers in the plurality including compressed I and Q signal samples of a corresponding baseband antenna-carrier channel, containers that are members of the set of containers for a given antenna-carrier channel including a corresponding block of compressed signal samples from the compressed I and Q signal samples for the given baseband antenna-carrier channel, and said disassembling includes

parsing the data structures to derive said plurality of sets of containers;

and

producing the corresponding sequences of compressed I and Q signal samples.

29. The method of claim 23, wherein said data structure includes a plurality of messages carrying payload derived from a packet comprising compressed I and Q signal samples of the plurality of baseband antenna-carrier channels.

30. The method of claim 23, wherein the step of disassembling is performed in accordance with a Common Public Radio Interface (CPRI) standard.

31. The method of claim 23, wherein the step of disassembling is performed in accordance with an Open Base Station Architecture Initiative (OBSAI) standard.