Transceiver apparatus and method for efficient high-speed data retransmission and decoding in a CDMA mobile communication system

• US 20030076870A1
• Filed: 10/18/2002
• Published: 04/24/2003
• Est. Priority Date: 10/19/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Moon, Yong-Suk, Kim, Hun-Kee, Yoon, Jae-Seung
• Granted Patent: US 7,027,782 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• 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 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/1893 Physical mapping arrangements physical resource mapping in general H04L5/00
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365

Abstract

A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system which separates coded bits output from an encoder into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits by a specific modulation technique. The method comprises determining orthogonal codes available for retransmission; separating the coded bits with higher priority and the coded bits with lower priority into a plurality of sub-packets with a given size, and selecting a part of the sub-packets or sub-packets to be repeatedly transmitted, depending on the determined number of available orthogonal codes; and transmitting a stream of symbols obtained by symbol-mapping coded bits of the selected sub-packets by the specific modulation technique, with the determined available orthogonal codes.

Claims

1. A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system, which separates coded bits output from an encoder at a given coding rate into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits with higher priority and the coded bits with lower priority by a specific modulation technique, with at least one available orthogonal code, the method comprising the steps of:

determining orthogonal codes available for retransmission;

separating the coded bits with higher priority and the coded bits with lower priority into a plurality of sub-packets with a given size, and selecting at least a portion of the sub-packets to be repeatedly transmitted, depending on the determined number of available orthogonal codes; and

transmitting a stream of symbols obtained by symbol-mapping coded bits of the selected sub-packets by the specific modulation technique, with the determined available orthogonal codes.

2. The method of claim 1, wherein the at least the portion of the sub-packets to be repeatedly transmitted are selected depending on the determined number of available orthogonal codes and the specific modulation technique, if the specific modulation technique is different from a modulation technique used during initial transmission or previous retransmission.

3. The method of claim 1, wherein a number of sub-packets selected from the plurality of sub-packets is determined according to the number D_r of coded bits calculated by

D_r=α

×

β

×

D_i, $D_r=\mathrm{\alpha <br><br>}\times <br><br>\mathrm{\beta <br><br>}\times <br><br>D_i,\mathrm{\alpha <br><br>}=\frac{{\log }_2<br><br>M_r}{{\log }_2<br><br>M_i}<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\beta <br><br>}=\frac{N_r}{N_i}$

where M_i indicates an integer corresponding to the modulation technique during initial transmission, and M_r indicates an integer corresponding to a modulation technique at retransmission, N_i indicates the number of codes available for initial transmission, N_r indicates the number of codes available for retransmission, and D_i denotes the number of coded bits transmitted during initial transmission.

4. The method of claim 3, wherein the specific modulation technique includes 64QAM (64-ary Quadrature Amplitude Modulation), 16QAM (16-ary Quadrature Amplitude Modulation), and QPSK (Quadrature Phase Shift Keying), and the integer M_i or M_r becomes 64 for 64QAM, 16 for 16QAM and 4 for QPSK.

5. The method of claim 1, wherein sub-packets comprised of the coded bits with higher priority are first selected in the step of selecting the sub-packets to be transmitted.

6. The method of claim 1, wherein previously non-transmitted sub-packets are first selected in the step of selecting the sub-packets to be transmitted.

7. An apparatus for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system, which separates coded bits output from an encoder at a given coding rate into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits with higher priority and the coded bits with lower priority by a specific modulation technique, with at least one available orthogonal code, the apparatus comprising:

a controller for determining orthogonal codes available for retransmission;

a selector for separating the coded bits with higher priority and the coded bits with lower priority into a plurality of sub-packets with a given size, and selecting at least a portion of the sub-packets to be repeatedly transmitted, depending on the determined number of available orthogonal codes;

a modulator for generating a stream of symbols by symbol mapping coded bits of the selected sub-packets by the specific modulation technique; and

a frequency spreader for transmitting the stream of symbols using the determined available orthogonal codes.

8. The apparatus of claim 7, wherein the controller selects the at least the portion of the sub-packets or sub-packets to be repeatedly transmitted, depending on the determined number of available orthogonal codes and the specific modulation technique, if the specific modulation technique is different from a modulation technique used at initial transmission or previous retransmission.

9. The apparatus of claim 7, wherein a number of sub-packets selected from the plurality of sub-packets is determined according to the number D_r of coded bits calculated by

D_r=α

×

β

×

D_i, $D_r=\mathrm{\alpha <br><br>}\times <br><br>\mathrm{\beta <br><br>}\times <br><br>D_i,\mathrm{\alpha <br><br>}=\frac{{\log }_2<br><br>M_r}{{\log }_2<br><br>M_i}<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\beta <br><br>}=\frac{N_r}{N_i}$

where M_i indicates an integer corresponding to the modulation technique at initial transmission, and M_r indicates an integer corresponding to a modulation technique at retransmission, N_i indicates the number of codes available for initial transmission, N_r indicates the number of codes available for retransmission, and D_i denotes the number of coded bits transmitted during initial transmission.

10. The apparatus of claim 9, wherein the specific modulation technique includes 64QAM (64-ary Quadrature Amplitude Modulation), 16QAM (16-ary Quadrature Amplitude Modulation), and QPSK (Quadrature Phase Shift Keying), and the integer M_i or M_r becomes 64 for 64QAM, 16 for 16QAM and 4 for QPSK.

11. The apparatus of claim 7, wherein the selector first selects sub-packets comprised of the coded bits with higher priority when selecting the sub-packets to be transmitted.

12. The apparatus of claim 7, wherein the selector first selects previously non-transmitted sub-packets when selecting the sub-packets to be transmitted.

13. A method for performing retransmission on initially transmitted coded bits by a transmitter in response to a retransmission request from a receiver in a CDMA (Code Division Multiple Access) mobile communication system including a channel encoder for encoding input data at a predetermined coding rate and outputting coded bits, the method comprising the steps of:

upon receiving a retransmission request from the receiver, determining a modulation technique and a number of available orthogonal codes, to be used at retransmission;

receiving coded bits from the channel encoder, and distributing the coded bits into systematic bits and parity bits;

receiving the systematic bits and the parity bits, and separately interleaving the received systematic bits and parity bits;

determining a number of coded bits to be transmitted depending on the determined modulation technique and the determined number of available orthogonal codes, to be used during retransmission, and selecting as many interleaved systematic bits and parity bits as the determined number of coded bits;

modulating the selected systematic bits and parity bits by the determined modulation technique, and outputting modulated symbols; and

frequency-spreading the modulated symbols with corresponding orthogonal codes among the available orthogonal codes.

14. The method of claim 13, wherein the modulation technique to be used during retransmission is determined according to a channel environment at an instant when the retransmission request is received.

15. The method of claim 13, wherein the number Dr of coded bits to be transmitted is determined by

D_r=α

×

β

×

D_i, $D_r=\mathrm{\alpha <br><br>}\times <br><br>\mathrm{\beta <br><br>}\times <br><br>D_i,\mathrm{\alpha <br><br>}=\frac{{\log }_2<br><br>M_r}{{\log }_2<br><br>M_i}<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\beta <br><br>}=\frac{N_r}{N_i}$

where M_i indicates an integer corresponding to a modulation technique at initial transmission, and M_r indicates an integer corresponding to a modulation technique at retransmission, N_i indicates the number of codes available for initial transmission, N_r indicates the number of codes available for retransmission, and D_i denotes the number of coded bits transmitted during initial transmission.

16. The method of claim 15, wherein the specific modulation technique includes 64QAM (64-ary Quadrature Amplitude Modulation), 16QAM (16-ary Quadrature Amplitude Modulation) and QPSK (Quadrature Phase Shift Keying), and the integer M_i or M_r becomes 64 for 64QAM, 16 for 16QAM and 4 for QPSK.

17. The method of claim 13, wherein the interleaved systematic bits are first selected in the step of selecting as many interleaved systematic bits and parity bits as the determined number of coded bits.

18. The method of claim 13, wherein previously non-transmitted systematic bits and parity bits are first selected in the step of selecting as many interleaved systematic bits and parity bits as the determined number of coded bits.

19. An apparatus for performing retransmission on initially transmitted coded bits by a transmitter in response to a retransmission request from a receiver in a CDMA (Code Division Multiple Access) mobile communication system including a channel encoder for encoding input data at a predetermined coding rate and outputting coded bits, the apparatus comprising:

a controller for determining a modulation technique and a number of available orthogonal codes to be used at retransmission, upon receiving a retransmission request from the receiver;

a distributor for receiving coded bits from the channel encoder, and distributing the coded bits into systematic bits and parity bits;

an interleaver for receiving the systematic bits and the parity bits, and separately interleaving the systematic bits and the parity bits;

a selector for determining a number of coded bits to be transmitted depending on the determined modulation technique and the determined number of available orthogonal codes, and selecting as many interleaved systematic bits and parity bits as the determined number of coded bits;

a modulator for modulating the selected systematic bits and parity bits by the determined modulation technique, and outputting modulated symbols; and

a frequency spreader for frequency-spreading the modulated symbols with corresponding orthogonal codes among the available orthogonal codes.

20. The apparatus of claim 19, wherein the controller determines the modulation technique to be used during retransmission according to a channel environment at an instant when the retransmission request is received.

21. The apparatus of claim 19, wherein the number Dr of coded bits to be transmitted is determined by

D_r=α

×

β

×

D_i, $D_r=\mathrm{\alpha <br><br>}\times <br><br>\mathrm{\beta <br><br>}\times <br><br>D_i,\mathrm{\alpha <br><br>}=\frac{{\log }_2<br><br>M_r}{{\log }_2<br><br>M_i}<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\beta <br><br>}=\frac{N_r}{N_i}$

where M_i indicates an integer corresponding to a modulation technique at initial transmission, and M_r indicates an integer corresponding to a modulation technique at retransmission, N_i indicates the number of codes available for initial transmission, N_r indicates the number of codes available for retransmission, and D_i denotes the number of coded bits transmitted during initial transmission.

22. The apparatus of claim 21, wherein the specific modulation technique includes 64QAM (64-ary Quadrature Amplitude Modulation), 16QAM (16-ary Quadrature Amplitude Modulation) and QPSK (Quadrature Phase Shift Keying), and the integer M_i or M_r becomes 64 for 64QAM, 16 for 16QAM and 4 for QPSK.

23. The apparatus of claim 19, wherein the selector first selects the interleaved systematic bits when selecting as many interleaved systematic bits and parity bits as the determined number of coded bits.

24. The apparatus of claim 19, wherein the selector first selects previously non-transmitted systematic bits and parity bits when selecting as many interleaved systematic bits and parity bits as the determined number of coded bits.

25. A method for receiving by a receiver data retransmitted from a transmitter in a mobile communication system, which separates coded bits output from an encoder at a given coding rate into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits with higher priority and the coded bits with lower priority by a specific modulation technique, with at least one available orthogonal code, the method comprising the steps of:

determining orthogonal codes available for retransmission;

despreading the received data with the determined available orthogonal codes and outputting a stream of modulated symbols;

demodulating the stream of modulated symbols by a demodulation technique corresponding to the specific modulation technique, and outputting coded bits;

separating the coded bits into the coded bits with higher priority and the coded bits with lower priority, and combining the separated coded bits with at least one of previously received coded bits; and

separately deinterleaving the combined coded bits with higher priority and the combined coded bits with lower priority, and channel-decoding the deinterleaved coded bits.

26. An apparatus for receiving by a receiver data retransmitted from a transmitter in a mobile communication system which separates coded bits output from an encoder at a given coding rate into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits with higher priority and the coded bits with lower priority by a specific modulation technique, with at least one available orthogonal code, the apparatus comprising:

a despreader for despreading the received data with as many available orthogonal codes as a number of available orthogonal codes used during retransmission, and outputting a stream of modulated symbols;

a demodulator for demodulating the stream of modulated symbols by a demodulation technique corresponding to the specific modulation technique;

a selective packet combiner for separating the coded bits into the coded bits with higher priority and the coded bits with lower priority, and combining the separated coded bits with at least one of the previously received coded bits;

a deinterleaver for separately deinterleaving the combined coded bits with higher priority and the combined coded bits with lower priority; and

a channel decoder for channel-decoding the deinterleaved coded bits with higher priority and the deinterleaved coded bits with lower priority.

27. A method for retransmitting coded bits by a transmitter in response to a retransmission request from a receiver in a mobile communication system, which separates coded bits output from an encoder at a given coding rate into coded bits with higher priority and coded bits with lower priority, and transmits from the transmitter to the receiver a stream of symbols obtained by symbol mapping the coded bits with higher priority and the coded bits with lower priority by a specific modulation technique, with at least one available orthogonal code, the method comprising the steps of:

upon receiving a retransmission request in response to a predetermined number of retransmission attempts, determining a modulation technique with a one-step lower modulation order than a modulation technique M_i at initial transmission as a modulation technique M_r to be used during retransmission, if the number N_r of orthogonal codes available for retransmission is larger than or equal to the number N_i of orthogonal codes available for initial transmission, and a channel condition at retransmission is worse than a channel condition at retransmission;

determining a modulation technique with a one-step higher modulation order than the modulation order M_i at initial transmission as a modulation technique M_r to be used during retransmission, if the number N_r of orthogonal codes available for retransmission is smaller than the number N_i of orthogonal codes available for initial transmission and a channel condition at retransmission is better than a channel condition at retransmission;

determining whether the number N_r of orthogonal codes available for retransmission is proper by applying the determined modulation technique M_r to the following equation,

$N_r\ge <br><br>\lceil <br><br>R\times <br><br>\frac{m_i}{m_r}\times <br><br>N_i\rceil <br><br>$

where m_k=log₂M_k, m_i=log₂M_i, and R is an integer; and

modulating at least one of the coded bits by the determined modulation technique M_r and retransmitting the modulated coded bits, if the number N_r of orthogonal codes available for retransmission is proper.