RECEIVER TERMINAL DRIVEN JOINT ENCODER AND DECODER MODE ADAPTATION FOR SU-MIMO SYSTEMS

• US 20110110449A1
• Filed: 05/03/2010
• Published: 05/12/2011
• Est. Priority Date: 05/05/2009
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Caire, Giuseppe, Sundberg, Carl-Erik W., Ramprashad, Sean A., Papadopoulos, Haralabos C.
• Granted Patent: US 9,048,977 B2
• Time in Patent Office: Days
• US Class Current: 375/261
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0017 where the mode-switching is based on Quality of Service requirement
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication

Abstract

A system, a method and an apparatus are disclosed herein for receiver terminal driven joint encoder and decoder mode adaptation for SU-MIMO transmission. In one embodiment, the system comprises a transmitter that is able to be directed to transmit wireless signals over a multiple-input, multiple output (MIMO) system using any of a plurality of encoding modes; and a user terminal having a receiver comprising a decoding module which has a plurality of decoding modes, each of which can be used to decode communications from the transmitter received over a multiple-input, multiple output (MIMO) channel, wherein at least one encoding mode is operable with multiple of the decoding modes. The system also comprises a joint selection module that is operable to select for the MIMO transmission the decoding mode from the plurality of decoding modes and an encoding mode from the plurality of encoding modes to be used by the transmitter on the channel, the selection being based on receiver-dependent criteria corresponding to the decoding mode associated with the encoding mode and channel information, receiver hardware and state, and application-specific constraints. The joint selection module is operable to send information to identify the encoding mode to the transmitter using a feedback channel.

Claims

1. A wireless communication system comprising:

a transmitter that is operable to transmit wireless signals using any of a plurality of encoding modes representing one or more transmission rates; and

a user terminal having a receiver comprising

a decoding module to decode communications from the transmitter over a multiple-input, multiple output (MIMO) channel using a decoding mode selected from a plurality of decoding modes, wherein at least one of the encoding modes is operable with more than one of the decoding modes,

a joint selection module to jointly select the decoding mode from the plurality of decoding modes and an encoding mode from the plurality of encoding modes to be used by the transmitter, the selection based on being able to successfully transmit a corresponding data stream at a rate given by the encoding mode given channel conditions, and additionally based on receiver-dependent criteria corresponding to the decoding mode associated with the encoding mode and channel information, receiver hardware and state, and application-specific constraints, the joint selection module being operable to send information to identify the encoding mode to the transmitter using a feedback channel.

2. The system defined in claim 1 wherein the characteristics of encoding modes comprise channel code design characteristics and modulation characteristics.

3. The system defined in claim 2 wherein the channel code design characteristics comprises one or more of code rate, code type and code memory.

4. The system defined in claim 2 wherein the modulation characteristics comprises one or more of constellation size, constellation points, and the mapping of bits to constellation points.

5. The system defined in claim 1 wherein the application-specific constraints comprise at least one of a bit-error rate, packet-error rate, block-error rate, frame-error rate, and a QoS metric.

6. The system defined in claim 1 wherein the receiver hardware and state indicate availability of receiver resources, the resources comprising a determination of an acceptable number of operations that may be performed and hardware resources that may be used in the decoding operation for a given transmission given resources the receiver determines can be used, the determination being based on the hardware state, and further wherein the hardware state defines one or more resources including the computational power of processors in the receiver, available power usage of the receiver, and available battery life of the receiver, and usage of resources for other applications.

7. The system defined in claim 1 wherein the receiver further comprises a channel estimator to generate a channel estimate based on measurements, the channel estimate being an estimate of the communication channel between a transmitter and the receiver.

8. The system defined in claim 1 wherein the receiver further comprises:

a list of encoding modes, wherein at least one encoding mode in the list of encoding modes comprises one or more of an outer code description and a modem choice;

a list of decoder modes, wherein at least one decoding mode in the list of decoding modes comprises one or more a decoder type and one or more decoder parameters; and

a set of look up tables to store one or more of performance data and decoding complexity measures associated with each viable pair of encoding and decoding modes from the list of encoding and decoding modes.

9. The system defined in claim 8 wherein the outer code description comprises one or more of code type, memory and rate, and wherein the modem choice comprises one or more of QAM constellation size, symbol points and bit to symbol mapping.

10. The system defined in claim 8 wherein the one or more decoder parameters comprise one or more of decoder iterations, and other decoder-type specific parameters.

11. The system defined in claim 1 wherein the receiver further comprises:

a list of encoding modes, wherein at least one encoding mode in the list of encoding modes comprises one or more of an outer code description and a modem choice;

a list of decoder modes, wherein at least one decoding mode in the list of decoding modes comprises one or more a decoder type and one or more decoder parameters; and

a set of look up tables to store values of parameters of an algorithm based on performance data and decoding complexity calculations.

12. The system defined in claim 1 wherein the joint selection module is operable to:

obtain a channel estimate;

obtain criteria from one or more of an application running on the receiver and hardware on the receiver;

identify a set of pairs of encoding and decoding modes based on the channel estimate and the criteria from the application or hardware on the receiver; and

select one pair containing the encoding mode and the decoding mode from the set of pairs.

13. The system defined in claim 1 wherein the transmitter comprises an encoding module to change the encoding performed by the transmitter based on the encoding mode selected by the receiver.

14. The system defined in claim 1 wherein the application-specific constraints comprise the bit-error rate requirements of an application, available computational resources for decoding transmissions while the application is running, available memory resources for decoding transmissions while the application is running, anticipated or required power usage of the application over its anticipated or required running time, and tolerance of the application to wait for retransmissions of data that may be lost in transmission.

15. A terminal for use in a wireless communication system comprising a transmitter that is operable to transmit wireless signals using a plurality of encoding modes, the terminal comprising a receiver having

a decoding module to decode communications from the transmitter over a multiple-input, multiple output (MIMO) channel using a decoding mode selected from a plurality of decoding modes, wherein at least one of the encoding modes is operable with more than one of the decoding modes;

and

a joint selection module to jointly select the decoding mode from the plurality of decoding modes and an encoding mode from the plurality of encoding modes to be used by the transmitter, the selection based on being able to successfully transmit a corresponding data stream at a rate given by the encoding mode with the given channel conditions, and additionally based on receiver-dependent criteria corresponding to the decoding mode associated with the encoding mode and channel information, receiver hardware and state, and application-specific constraints, the joint selection module being operable to send information to identify the encoding mode to the transmitter using a feedback channel.

16. The terminal defined in claim 15 wherein the characteristics of encoding and decoding modes comprise code design characteristics and modulation characteristics.

17. The terminal defined in claim 15 wherein the application-specific constraints comprise at least one of a bit-error rate, packet-error rate, block-error rate, frame-error rate, application required bitrate, and a QoS metric.

18. The terminal defined in claim 15 wherein the receiver hardware state comprises one or more of the computational power of processors in the receiver, the available power usage and battery life of the receiver and the usage of such resources by other applications.

19. The terminal defined in claim 15 wherein the receiver further comprises a channel estimator to generate a channel estimate from measurements, the channel estimate being an estimate of the communication channel between a transmitter and the receiver.

20. The terminal defined in claim 15 wherein the receiver further comprises:

a list of encoding modes, wherein at least one encoding mode in the list of encoding modes comprises one or more of an outer code description and a modem choice;

a list of decoder modes, wherein at least one decoding mode in the list of decoding modes comprises one or more a decoder type and one or more decoder parameters; and

a set of look up tables to store one or more of performance data and decoding complexity associated with each viable pair of encoding and decoding modes from the list of encoding and decoding modes.

21. The terminal defined in claim 15 wherein

the outer code description comprises one or more of code type, memory and rate;

the modem choice comprises one or more of QAM constellation size, symbol points and bit to symbol mapping; and

the one or more decoder parameters comprise one or more of iterations, decoder-type specific parameters.

22. The terminal defined in claim 15 wherein the joint selection module is operable to:

obtain a channel estimate;

obtain criteria from one or more of an application running on the receiver and hardware on the receiver;

identify a set of pairs of encoding and decoding modes based on the channel estimate and the criteria from the application or hardware on the receiver; and

select one pair containing the encoding mode and the decoding mode from the set of pairs.

23. The terminal defined in claim 15 wherein the receiver further comprises:

a list of encoding modes, wherein at least one encoding mode in the list of encoding modes comprises one or more of an outer code description and a modem choice;

a list of decoder modes, wherein at least one decoding mode in the list of decoding modes comprises one or more decoder types and one or more decoder parameters; and

a set of look up tables to store values of parameters of an algorithm based on performance data and decoding complexity calculations.

24. A method comprising:

estimating a MIMO channel at a receiver in a wireless communication system, the channel for communications between a transmitter and the receiver;

jointly selecting the decoding mode from the plurality of decoding modes and an encoding mode from the plurality of encoding modes to be used by the transmitter, the selection based on being able to successfully transmit a corresponding data stream at a rate given by the encoding mode given the channel conditions, based on receiver-dependent criteria corresponding to the decoding mode associated with the encoding mode and channel information, receiver hardware and state, and application-specific constraints; and

sending information to identify the encoding mode to the transmitter using a feedback channel.