Method and transmitter for channel coding and modulation in the frequency domain of orthogonal frequency-division multiplexing wireless networks

Patent metadata

Field	Value
Publication number	US-9742524-B2
Application number	US-201514709873-A
Country	US
Kind code	B2
Filing date	May 12, 2015
Priority date	May 12, 2014
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

The method comprising: applying, by a transmitter, a Forward Error Correction to an information block to be sent to a receiver and modulating said information block prior to its transmission, wherein the transmitter has knowledge of a channel frequency response seen by the receiver and the applying and modulating are performed at a variable-rate, at the transmitter side, by: transforming the information block into a number of smaller packets denoted as codeblocks fitting the input sizes accepted by the Forward Error Correction; selecting, a set of modulation and coding schemes to be independently applied to each of the codeblocks; including, information about the selected set of modulation and coding schemes within part of physical resources devoted to user data by reserving specific subcarriers and OFDM symbols; and mapping, said information within physical resources devoted to user data and not reserved for said selected set of modulation and coding schemes, first in order of ascending OFDM symbols and then of ascending subcarriers.

First claim

The invention claimed is:

1. A method for variable rate channel coding and modulation in a frequency domain of Orthogonal Frequency-Division Multiplexing (OFDM) wireless networks, the method comprising:
partitioning, at a transmitter, user data into a plurality of codeblocks, each codeblock fitting input sizes accepted by Forward Error Correction (FEC);
performing, at the transmitter, FEC on the codeblocks;
applying, at the transmitter, a modulation and coding scheme (MCS) to each codeblock based on a channel frequency response received from a receiver of a channel over which the codeblock is to be transmitted, the MCS comprising a modulation order and a coding rate for the codeblock that best fits the channel frequency response of the channels;
including, at the transmitter, information about the MCS applied to each codeblock within a part of physical resources devoted to the user data by reserving specific subcarriers and OFDM symbols for the information and inserting the information about the MCSs of the codeblocks into the reserved specific subcarriers and OFDM symbols; and
mapping, at the transmitter, the modulated user data within the physical resources devoted to the user data and not reserved for the information about the MCSs, first in order of ascending OFDM symbols and then in order of ascending subcarriers.

2. The method of claim 1 , wherein values of an MCS applied to a codeblock are given by the equation:
MCS i =MCS avg +ΔMCS i ;

where MCS i denotes values of the MCS applied to the i-th codeblock, MCS avg is an MCS value applied to a whole transmission, and ΔMCS i denotes differential MCS values with respect to the MCS avg to be applied to the i-th codeblock.

3. The method of claim 2 , wherein the information about the MCSs comprises only the differential MCS values of the codeblocks.

4. The method of claim 3 , further comprising encoding the differential MCS values through a Forward Error Correction method and further modulating the encoded differential MCS values using a constellation mapping function including at least a Binary Phase Shift Keying modulation that protects the encoded differential MCS values against channel impairments.

5. The method of claim 1 , further comprising transmitting the mapped user data and included information about the MCSs,
wherein an allocated bandwidth for transmission is greater than a coherence bandwidth of the channel.

6. The method of claim 1 , wherein the codeblocks have the same sizes prior to performing the Forward Error Correction.

7. The method of claim 6 , comprising matching the sizes of the codeblocks after the FEC to available physical resources, and adjusting values of the MCS for each codeblock.

8. The method of claim 7 , wherein the sizes of the codeblocks are adjusted after Forward Error Correction to reserve part of the available physical resources for the information on the MCSs applied to the codeblocks.

9. The method of claim 1 , wherein the OFDM wireless network is a Long Term Evolution (LTE) network and the transmitter is a base station or a user terminal.

10. The method of claim 1 , comprising applying transmit diversity to the mapped user data and included information about the MCSs.

11. The method of claim 1 , wherein the channel frequency response is reported from the receiver to the transmitter in Frequency Division Duplex (FDD) mode, or directly estimated by the transmitter in Time Division Duplex (TDD) mode.

12. The method of claim 1 , wherein application of the variable rate channel coding and modulation is signaled from a base station to a user terminal by a control message.

13. A transmitter for variable rate channel coding and modulation in a frequency domain of Orthogonal Frequency-Division Multiplexing (OFDM) wireless networks, the transmitter having knowledge of a channel frequency response as seen by the receiver and comprising a memory and at least one microprocessor that in operation with the memory is configured to:
partition user data into a plurality of codeblocks, each codeblock fitting input sizes accepted by Forward Error Correction (FEC);
perform FEC on the codeblocks;
apply a modulation and coding scheme (MCS) to each codeblock based on a channel frequency response received from a receiver of a channel over which the codeblock is to be transmitted, the MCS comprising a modulation order and a coding rate for the codeblock that best fits the channel frequency response of the channel;
include information about the MCS applied to each codeblock within a part of physical resources devoted to the user data by reserving specific subcarriers and OFDM symbols for the information and inserting the information about the MCSs of the codeblocks into the reserved specific subcarriers and OFDM symbols; and
map the modulated user data within the physical resources devoted to the user data and not reserved for the information about the MCSs, first in order of ascending OFDM symbols and then in order of ascending subcarriers.

14. The transmitter of claim 13 , wherein the at least one microprocessor is further configured to match sizes of the codeblocks after the Forward Error Correction to available physical resources.

Assignees

• Telefonica Sa

Inventors

• Lorca Hernando Javier

Classifications

• H04L1/0041

  Arrangements at the transmitter end · CPC title

• H04L5/0007

  the frequencies being orthogonal, e.g. OFDM(A) or DMT · CPC title

• H04L1/0003 Primary

  by switching between different modulation schemes · CPC title

• H04L1/0013

  Rate matching, e.g. puncturing or repetition of code symbols · CPC title

• H04L1/0025

  Transmission of mode-switching indication · CPC title