Channel allocation method and device for coded and combined information sets

• US 6,985,534 B1
• Filed: 10/27/1999
• Issued: 01/10/2006
• Est. Priority Date: 10/27/1998
• Status: Expired due to Term

• Current Assignee: Nokia Solutions and Networks GmbH & Co. KG (Nokia Corporation)
• Original Assignee: Siemens AG
• Inventors: Meister, Wolfgang
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/807,741
• Time in Patent Office: 2,267 Days
• Field of Search: 375/130, 375/140, 375/133, 375/146, 375/147, 375/259, 375/260, 375/265, 370/203, 370/206, 370/319, 370/281, 370/208, 370/210
• US Class Current: 375/260
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0096 Indication of changes in allocation

Abstract

In a device for transmitting a sequence of information symbols over a plurality of partial channels having different transmission characteristics and together forming a transmission channel, the sequence of information symbols is grouped (102), whereupon a first set and a second set of the information symbols are coded (103a, 103b) using different coding methods. The coded information symbols are then combined in sets (104a, 104b) and are transmitted over a channel having two sets of partial channels. Both the first and the second set of partial channels have at least one partial channel whose signal-to-noise ratio without combining would be lower than a threshold signal-to-noise ratio which is minimally required by the coding method used for the set to which this partial channel belongs in order to achieve a predetermined reliability when decoding the information symbols and whose signal-to-noise ratio is greater than or equal to the threshold signal-to-noise ratio as a result of the combination step. The concept of transmitting and receiving according to the present invention permits an increased transmission rate since there is at least one partial channel in each set as a result of the setwise combination.

Claims

1. A device for transmitting information over a plurality of partial channels which have different transmission characteristics and which together form a transmission channel, comprising:

a unit for grouping (102) the information as assigned to the partial channels;

a unit for coding (103a) information assigned to a first set of partial channels by means of a first coding method to obtain a first set of coded information symbols, where a first coded information symbol of the first set of coded information symbols has a first amount of information assigned to said first coded information symbol;

a unit for coding (103b) information assigned to a second set of partial channels by means of a second coding method to obtain a second set of coded information symbols, where a second coded information symbol of the second set of coded information symbols has a second amount of information assigned to said second coded information symbol which differs from the first amount of information;

a unit for combining (104a) the coded information symbols of the first set according to a first combination specification so as to generate a first set of combined coded information symbols equal in number to the number of partial channels of the first set of partial channels;

a unit for combining (104b) the coded information symbols of the second set according to a second combination specification so as to generate a second set of combined coded information symbols equal in number to the number of partial channels of the second set of partial channels; and

a unit for assigning (106) the combined coded information symbols of the first set to the first set of partial channels and for assigning the combined coded information symbols of the second set to the second set of partial channels in such a way that each partial channel has a combined coded information symbol assigned to said each partial channel, that each partial channel of the first set of partial channels has the whole information of the information symbols of the first set assigned to said each partial channel of the first set of partial channels, and that each partial channel of the second set of partial channels has the whole information of the information symbols of the second set assigned to said each partial channel of the second set of partial channels;

where both the first and the second set of partial channels have at least one partial channel whose signal-to-noise ratio without combining would be lower than a threshold signal-to-noise ratio that is minimally necessary for the coding method used by the set to which this partial channel belongs in order to achieve a predetermined reliability when decoding the information symbols, and whose signal-to-noise ratio as a result of combining is greater than or equal to the threshold signal-to-noise ratio.

2. A device according to claim 1, wherein each partial channel of the transmission channel has a carrier with its own frequency assigned to said each partial channel of the transmission channel and wherein the unit for assigning has a unit (106) for impressing the combined coded information symbols on the corresponding carriers so as to generate a modulated signal representing the sequence of information symbols.

3. A device according to claim 1 or 2, wherein the first coding method (103a) is a method with a 2^x-stage quantization of the signal space and wherein the second coding method (103b) is a method with a 2^x-y quantization of the signal space, where x=3, x>

y.

4. A method according to claim 3, wherein the number of partial channels in a set of partial channels is so chosen that the excess in the signal-to-noise ratio of carriers in the set is essentially completely used to compensate for the deficit in the signal-to-noise ratio of the at least one partial channel in the set in such a way that all the partial channels in the set have a signal-to-noise ratio which is greater than the threshold signal-to-noise ratio and which is as close as possible to the threshold signal-to-noise ratio.

5. A method according to claim 3 or 4, wherein the transmission channel (108) has a plurality of carriers with carrier frequencies from a lower threshold frequency to a higher threshold frequency, where the first set of partial channels has carrier frequencies from the lower threshold frequency up to and including a middle frequency and where the second set of partial channels has carrier frequencies above the middle frequency up to the upper threshold frequency and where the middle frequency is so specified that for the parameter x=3 the signal-to-noise ratio of the carrier with the middle frequency is closest to the threshold signal-to-noise ratio (300) for the first set of partial channels as a result of combining by means of the first combination specification (104a) and where the upper threshold frequency is so specified that the signal-to-noise ratio of the carrier with carrier frequency equal to the upper threshold frequency is closest to the threshold signal-to-noise ratio for the second set of partial channels.

6. A method according to claim 3, wherein the transmission channel has a plurality of carriers with carrier frequencies from a lower threshold frequency to an upper threshold frequency, where there is a number of units for encoding and an equally large number of units for combining the coded information symbols for the respective sets of partial channels, the number being so chosen that, for the set with the upper threshold frequency, a coding method with the coarsest possible quantization is employed in the respective coding unit and where a coding method which is successively a stage finer for smaller carrier frequencies is employed in a respective coding unit, so that, for the carrier at the lower threshold frequency, a coding unit is employed whose quantization is as fine as possible, with the result that the data rate for the full bandwidth of the channel from the lower threshold frequency to the upper threshold frequency is a maximum.

7. A device according to one of the preceding claims, which also has a unit for performing a forward error correction for partial channels, where the unit for performing a forward error correction is so designed that part of the gain in data rate is used to introduce redundancy into the sequence of information symbols, whereas the rest of the gain in data rate is used to increase the information rate.

8. A device according to one of the previous claims, wherein the transmission characteristics of the partial channels, which affect the threshold signal-to-noise ratio, are known, where the amounts of information of the first and the second coding unit (103a, 103b) are specified from the start in order to be able to transmit a certain information rate.

9. A device according to one of the claims 1 to 7, wherein the transmission characteristics of the partial channels, which affect the threshold signal-to-noise ratio, can be estimated roughly, so that the amounts of information and an assignment of partial channels to the first and second set of partial channels are so chosen that, as a result of combining, the signal-to-noise ratios of the partial channels exceed the estimated threshold signal-to-noise ratios for the partial channels by a security margin.

10. A device according to one of the preceding claims, wherein a partial channel which is known to have a poor transmission characteristic is not assigned to any set of partial channels.

11. A device according to one of the preceding claims, wherein the partial channels are assigned to the sets of partial channels according to their transmission characteristics, which are known beforehand, so that a set of partial channels has partial channels with similar transmission characteristics.

12. A device according to one of the claims 1 to 10, which also has a unit for dynamically registering the transmission channel and which also has a unit for dynamically determining the amount of information which is assigned by the first and second coding unit (103a, 103b) and for dynamically assigning carriers to the first and second set of partial channels, so that, as a result of combining, the signal-to-noise ratios of the partial channels are always greater than or equal to the threshold signal-to-noise ratios.

13. A device according to claim 2, wherein the unit (106) for impressing the combined information symbols on the corresponding carriers has a unit for performing an inverse discrete Fourier transform (IDFT), which is preferably implemented in the form of a fast discrete inverse Fourier transform (fast DIFT).

14. A device according to one of the preceding claims, wherein the first and the second combination specification of the units for combining (104a, 104b) are combination specifications for combining the information symbols in an essentially orthogonal and essentially normalized, i.e. in an essentially orthonormal or unitary, way.

15. A device according to claim 14, wherein the first and the second combination specification are a Hadamard matrix or a pseudo random noise matrix (P) or some other sufficiently orthonormal or unitary matrix (P) whose matrix elements are equal to or close to 1.

18. A device according to claim 14 or 15, wherein the first and the second combination specification are combination specifications for combining the information symbols in an essentially orthogonal and essentially normalized, i.e. in an essentially orthonormalized or unitary, way, and wherein the first and the second processing specification are the inverses of these combination specifications.

19. A device according to claim 18, wherein the first and the second processing specification are inverse Hadamard matrices or inverse pseudo random noise matrices or some other sufficiently orthonormal or unitary matrices which are sufficiently inverse to the combination specification and whose matrix elements are equal to or close to 1.

16. A device for receiving a transmitted signal with information, where a first set of coded information symbols of the transmitted signal is generated by a first coding method, where the first coding method has assigned a first amount of information to a coded information symbol of the first set of coded information symbols, and where a second set of coded information symbols is generated by a second coding method, where the second coding method has assigned a second amount of information, different from the first amount of information, to a coded information symbol of the second set of coded information symbols, where coded information symbols of the first set are combined according to a first combination specification and coded information symbols of the second set are combined according to a second combination specification, where combined coded information symbols of the first set are assigned to a first set of partial channels and where combined coded information symbols of the second set are assigned to a second set of partial channels, where both the first and the second set of partial channels have at least one partial channel whose signal-to-noise ratio without the step of combining would be lower than a threshold signal-to-noise ratio which is minimally necessary for the coding method used by the set to which this partial channel belongs in order to achieve a predetermined reliability when decoding the information symbols and whose signal-to-noise ratio with the step of combining is greater than or equal to the threshold signal-to-noise ratio, comprising:

a unit for extracting (110) the combined coded information symbols of the partial channels from the received signal using the partial channels;

a first unit for processing (114a) the combined coded information symbols of the first set using a first processing specification, which is the inverse of the first combination specification, so as to obtain the coded information symbols of the first set;

a second unit for processing (114b) the combined coded information symbols of the second set using a second processing specification, which is the inverse of the second combination specification, so as to obtain the coded information symbols of the second set;

a first unit for decoding (115a) the coded information symbols of the first set so as to recapture the information assigned to the coded information symbols of the first set, the first unit for decoding being designed to also decode the at least one partial channel of the first set of partial channels; and

a second unit for decoding (115b) the coded information symbols of the second set so as to recapture the information assigned to the coded information symbols of the second set, the second unit for decoding being designed to also decode the at least one partial channel of the second set of partial channels.

17. A device according to claim 16, wherein the unit (110) for extracting the combined coded information symbols has a unit for performing a discrete Fourier transform (DFT), which is preferably implemented in the form of a fast Fourier transform (FFT).

20. A device according to claim 16, which also has a unit for equalizing the received signal which is so designed that said unit for equalizing normalizes the amplitudes of the signals of the partial channels, the unit for equalizing following the unit for extracting the combined coded information symbols.

21. A method for transmitting information over a plurality of partial channels which have different transmission characteristics and together form a transmission channel, with the following steps:

grouping (102) the information as assigned to the partial channels;

coding (103a) information assigned to a first set of partial channels by means of a first coding method to obtain a first set of coded information symbols, where a first coded information symbol of the first set of coded information symbols has a first amount of information assigned to said first coded information symbol;

coding (103b) information assigned to a second set of partial channels by means of a second coding method to obtain a second set of coded information symbols, where a second coded information symbol of the second set of coded information symbols has a second amount of information assigned to said second coded information symbol which differs from the first amount of information;

combining (104a) the coded information symbols of the first set according to a first combination specification so as to generate a first set of combined coded information symbols equal in number to the number of partial channels of the first set of partial channels;

combining (104b) the coded information symbols of the second set according to a second combination specification so as to generate a second set of combined coded information symbols equal in number to the number of partial channels of the second set of partial channels; and

assigning (106) the combined coded information symbols of the first set to the first set of partial channels and assigning the combined coded information symbols of the second set to the second set of partial channels in such a way that each partial channel has a combined coded information symbol assigned to said each partial channel, that each partial channel of the first set of partial channels has the whole information of the information symbols of the first set assigned to said each partial channel of the first set of partial channels, and that each partial channel of the second set of partial channels has the whole information of the information symbols of the second set assigned to said each partial channel of the second set of partial channels;

where both the first and the second set of partial channels have at least one partial channel whose signal-to-noise ratio without combining would be lower than a threshold signal-to-noise ratio that is minimally necessary for the coding method used by the set to which this partial channel belongs in order to achieve a predetermined reliability when decoding the information symbols, and whose signal-to-noise ratio as a result of combining is greater than or equal to the threshold signal-to-noise ratio.

22. A method for receiving a transmitted signal with information, where a first set of coded information symbols of the transmitted signal is generated by a first coding method, where the first coding method has assigned a first amount of information to a coded information symbol of the first set of coded information symbols, and where a second set of coded information symbols is generated by a second coding method, where the second coding method has assigned a second amount of information, different from the first amount of information, to a coded information symbol of the second set of coded information symbols, where coded information symbols of the first set are combined according to a first combination specification and coded information symbols of the second set are combined according to a second combination specification, where combined coded information symbols of the first set are assigned to a first set of partial channels and where combined coded information symbols of the second set are assigned to a second set of partial channels, where both the first and the second set of partial channels have at least one partial channel whose signal-to-noise ratio without the step of combining would be lower than a threshold signal-to-noise ratio which is minimally necessary for the coding method used by the set to which this partial channel belongs in order to achieve a predetermined reliability when decoding the information symbols and whose signal-to-noise ratio with the step of combining is greater than or equal to the threshold signal-to-noise ratio, with the following steps:

extracting (110) the combined coded information symbols of the partial channels from the transmitted signal using the partial channels;

processing (114a) the combined coded information symbols of the first set using a first processing specification, which is the inverse of the first combination specification, so as to obtain the coded information symbols of the first set;

processing (114b) the combined coded information symbols of the second set using a second processing specification, which is the inverse of the second combination specification, so as to obtain the coded information symbols of the second set;

decoding (115a) the coded information symbols of the first set so as to recapture the information assigned to the coded information symbols of the first set, the first unit for decoding being designed to also decode the at least one partial channel of the first set of partial channels; and

decoding (115b) the coded information symbols of the second set so as to recapture the information assigned to the coded information symbols of the second set, the second unit for decoding being designed to also decode the at least one partial channel of the second set of partial channels.

23. A method according to claim 22, which also has the following step preceding the processing steps:

normalizing (112) the partial channels in such a way that, following normalization, the value of the power is substantially the same for each partial channel.