AU2013231171B2 - Method and apparatus for transmitting/receiving control information in a wireless communication system - Google Patents

Abstract

Abstract A method for transmitting control information in a communication system, comprising the steps of: determining signaling information for a physical layer to be transmitted 5 in a frame; generating at least one coded block from signaling information having a variable number of bits included in the signaling information for the physical layer; and transmitting a frame including the at least one coded block, wherein the frame includes a coded block 10 including other signaling information having a fixed number of bits required for receiving the signaling information having the variable number of bits. 4704598 1 (GHMalers- P85094 A J 1 23/09/2013 [Fig. 3] co6 :- ;>- Z 0w C ocC - - 2 o i-) a: - c- C LL c c~~ O -2 m C0 2 2 a o cn L en 0 l o o z z < U - LU cf) -J2 02 2 xc 'C a o a: L co m cr LUvj I CC -- 2 Dc CL +-- H

Description

METHOD AND APPARATUS FOR TRANSMITTING/RECEIVING CONTROL INFORMATION IN A WIRELESS COMMUNICATION SYSTEM Related Application This application is a divisional application of 5 Australian application no. 2009220329 the disclosure of which is incorporated herein by reference. Most of the disclosure of that application is also included herein, however, reference may be made to the specification of application no. 2009220329 as filed or accepted to gain 10 further understanding of the invention claimed herein. Technical Field The present invention generally relates to a method and apparatus for transmitting/receiving control information in a wireless communication system. More particularly, the 15 present invention relates to a method and apparatus for transmitting/receiving physical layer control information in a wireless communication system. Background Art FIG. 1 illustrates a conventional transmission scheme 20 for a frame including control information in a wireless communication system, especially in a wireless digital broadcasting system. Referring to FIG. 1, reference numeral 101 denotes one frame. The frame 101 includes a preamble 102, Layer 1 (L1) 25 signaling information 103, Layer 2 (L2) signaling information 104, and at least one Physical Layer Pipe (PLP) 105 to 107. The control information can be delivered in the preamble 102, the Li signaling information 103, and the L2 signaling information 104, and data is carried in the PLPs 30 105 to 107. The preamble 102 is used for time and frequency synchronization and frame synchronization at a receiver. The Li signaling information 103 is referred to as P2 because it is transmitted in a P2 symbol. P2 represents L1, i.e. 35 physical layer signaling information. The Li signaling information 103 includes static, configurable, and dynamic information as indicated by reference numerals 108, 109 and 110, respectively. The static information 108 is almost constant in time, including information about a cell Identifier (ID), a network ID, the number of Radio Frequency (RF) channels, a frame length, and 5 the positions of pilot subcarriers. The configurable information 109 does not change in every frame, but includes information that can be configurable in an upcoming frame. Therefore, the configurable information 109 includes information about a service ID, a modulation scheme, and a 10 code rate used for transmitting service data. The dynamic information 100 may vary in every frame, including the position of each PLP carrying service data in a current frame, i.e. the start and end of each PLP. In FIG. 1, the L2 signaling information 104 is signaling information 15 about Layer 2 (L2), that is, a Medium Access Control (MAC) layer. A PLP carrying the L2 signaling information 104 is referred to as PLP 0. PLP 0 includes information about the connection between a PLP and a broadcasting service, describing a PLP in which a particular service is received. 20 The PLPs 105 to 107, PLP 1 to PLP N, convey at least one service channel. As the PLPs 105 to 107 carry actual broadcasting data, they are also referred to as data PLPs. To receive a specific broadcasting service channel, a receiver acquires frame synchronization from the preamble 25 102 and achieves information about a data transmission scheme and a frame length from P2, that is, the Li signaling information 103. The receiver then detects PLPs carrying the intended service channel from PLPO, that is, the L2 signaling information 104, and receives broadcasting data in 30 the PLPs. In the case of control information such as signaling information, it may include a large number of dummy bits during encoding in the wireless communication system. These dummy bits dissipate communication resources. Accordingly, 35 there exists a need for a method for encoding control information to efficiently use communication resources. Summary of Invention In accordance with an aspect of an embodiment of the present invention, there is provided a method for 40 transmitting control information in a communication system, comprising the steps of: determining signaling information for a physical layer to be transmitted in a frame; generating at least one coded block from signaling 5 information having a variable number of bits included in the signaling information for the physical layer; and transmitting a frame including the at least one coded block, wherein the frame includes a coded block including other 10 signaling information having a fixed number of bits required for receiving the signaling information having the variable number of bits, wherein the signaling information having the variable number of bits includes frequency information about a radio 15 frequency (RF) channel for transmitting at least one physical layer pipe (PLP). In accordance with another aspect of an embodiment of the present invention, there is provided an apparatus for transmitting control information in a communication system, 20 comprising: an encoder configured to encode received information in a predetermined coding scheme; a transmitter configured to transmit a frame; and a controller configured to control the encoder to 25 generate at least one coded block from signaling information having a variable number of bits included in signaling information for a physical layer, and the transmitter to transmit a frame including the at least one coded block, wherein the frame includes a coded block including other 30 signaling information having a fixed number of bits required for receiving the signaling information having the variable number of bits, wherein the signaling information having the variable number of bits includes frequency information about a radio 35 frequency (RF) channel for transmitting at least one physical layer pipe (PLP). Advantageous Effects One or more embodiments of the present invention can transmit and receive control information more efficiently by 40 decreasing the number of dummy bits, when the control information is encoded and transmitted. Especially when control information, that is, physical layer signaling information is transmitted in a plurality of LDPC codewords, a codeword having a fixed number of bits is transmitted and received according to the types of control information. 5 Therefore, a transmitter and a receiver are simplified in structure. Brief Description of Drawings Objects, features and advantages of certain embodiments of the present invention will be more apparent from the 10 following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a conventional transmission scheme for a frame including control information in a wireless communication system, especially in a wireless digital 15 broadcasting system; FIG. 2 illustrates a method for encoding control information in a wireless communication system to which the present invention is applied; FIG. 3 illustrates a control information encoding 20 method in the wireless communication system according to an embodiment of the present invention; FIG. 4 illustrates the structures of first and second codewords as control information encoded in the method of FIG. 3; 25 FIG. 5 is a flowchart illustrating a method for transmitting control information in a transmitting control information in a transmitter in the wireless communication system according to an embodiment of the present invention; FIG. 6 is a flowchart illustrating a method for 30 receiving control information in a receiver in the wireless communication system according to an embodiment of the present invention; FIG. 7 is a block diagram of the transmitter in the wireless communication system according to an embodiment of 35 the present invention; and FIG. 8 is a block diagram of the receiver in the wireless communication system according to an embodiment of the present invention. Throughout the drawings, the same drawing reference 5 numerals will be understood to refer to the same elements, features and structures. Detailed Description of Embodiments of the Invention The matters defined in the description such as a detailed construction and elements are provided to assist in 10 a comprehensive understanding of exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, 15 descriptions of well-known functions and constructions are omitted for clarity and conciseness. FIG. 2 illustrates a method for encoding control information in a wireless communication system to which the present invention is applied. Specifically, the control 20 information is the Li signaling information illustrated in FIG. 1. Referring to FIG. 2, Li signaling information further includes Li pre-signaling information 202 in addition to Li static information 203, Li configurable information 204, and 25 Li dynamic information 205 that have been described before with reference to FIG. 1. The Li pre-signaling information 202 provides information about a transmission scheme for the Li static information 203, the Li configurable information 204, and the Li dynamic information 205. That is, the Li 30 pre-signaling information 202 indicates subcarriers, modulation schemes (Quadrature Phase Shift Keying (QPSK), 16-ary Quadrature Amplitude Modulation (16QAM), 64QAM, etc.), and code rates used for the Li static information 203, the Li configurable information 204, and the Li dynamic 35 information 205. While specific numbers of bits are described for the Li pre-signaling information 202, the Li static information 203, the Li configurable information 204, and the Li dynamic information 205, they are mere examples to which the present invention is not limited.

A transmitter creates a codeword by LDPC-decoding the Li pre-signaling information 202 independently, as indicated by reference numeral 206 and another codeword by LDPC encoding the Li static information 203, the Li configurable 5 information 204, and the Li dynamic information 205 collectively, as indicated by reference numeral 207. For the input of a relatively small number of input bits, for example, 200 to 300 bits, the LDPC code generally has poor coding performance. 10 In the illustrated case of FIG. 2, for the Li pre signaling information 202, no more than 41 input bits are added with 227 dummy bits and 32 Cyclic Redundancy Check (CRC) bits. The resulting 300 bits are encoded into one codeword. As described above, as many as 227 bits are used 15 as dummy bits to transmit 73-bit information including the 41-bit Li pre-signaling information and the 32-bit CRC, which is very inefficient. In accordance with a control information encoding method of the present invention, a first codeword is 20 generated by encoding the Li pre-signaling information 202 and predetermined default information of the Li static information 203 (referred to as default Li static information) and a second codeword is generated by encoding the remaining additional Li static information, the Li 25 configurable information 204, and the Li dynamic information 205. Notably, the remaining additional Li static information is optional in the present invention. FIG. 3 illustrates a control information encoding method in the wireless communication system according to an 30 embodiment of the present invention. Referring to FIG. 3, for encoding control information such as Li signaling information, a first codeword 307 is generated by encoding Li pre-signaling information 302 and default Li static information 303 extracted from Li static 35 information. An example of the default Li static information 303 will be described in detail with reference to FIG. 4. The input of the Li static information for the first codeword 307 is for improving performance by decreasing dummy bits considerably, compared to the conventional 40 technology. The reason for inputting the default Li static information 303 is to maintain the amount and type of input information of the first codeword. A second codeword 308 is generated by encoding additional Li static information 304, Li configurable 5 information 305, and Li dynamic information 306. The additional Li static information 304 is optional, which will be described in detail with reference to FIG. 4. In FIG. 3, LDPC coding is adopted for creating the first and second codewords 307 and 308, by way of example. 10 FIG. 4 illustrates the structures of the first and second codewords as control information encoded in the method of FIG. 3. Referring to FIG. 4, reference numeral 403 denotes an example of Li pre-signaling information and default Li 15 static information. Time Frequency Slicing (TFS) represents transmission of one PLP on a plurality of Radio Frequency (RF) channels. In Table 403, NUMRF at the start of fields indicated by an arrow 406 indicates the number of RF channels carrying one PLP. When one PLP is transmitted on a 20 plurality of RF channels, that is, TFS mode is used, NUMRF is greater than 1. If one PLP is transmitted on one RF channel, NUM RF is 1. There are as many main RFFrequency fields as the value of NUMRF. RFFrequency indicates an RF frequency, usually occupying 32 bits. In the present 25 invention, the first of one or more RFFrequency fields is included in the first codeword. If NUMRF is greater than 1, as many RFFrequency fields as "NUMRF-1" can be included in the second codeword. This configuration of the input information of each codeword can fix the bit numbers and 30 types of the input information of the first codeword. Main fields of the Li pre-signaling information listed in Table 403 are "TYPE" indicating the type of a stream transmitted in a frame, "Li COD" indicating the code rate of Part II information 402, "Li MOD" indicating the modulation 35 scheme of the Part II information 402, "LiFECTYPE" indicating an Li Forward Error Correction (FEC) type used for the Part II information 402 (e.g. a 16k LDPC block), "LiPSIZE" indicating the size of the coded and modulated Part II information 402, "BW EXT" is an indicator specific 40 to a geographical cell in a network, "NETWORKID" identifying a current network, "T2_SYSTEMID" identifying a system, and "RFIDX" is the index of an RF channel. Reference numeral 407 denotes another example of the first and second codeword configuration. In Table 403, FEF 5 is a field indicating whether a Further Extension Frame (FEF) is used. An FEF is a frame defined to allow some frame to be transmitted in a future technology. If FEF is 0, an FEF is not used in the current system. If FEF is 1, an FEF is used in the current system. Control information about 10 Further Extension Frame is added in Table 404. As noted from Table 403, the input information of each codeword is configured such that only necessary information is included in the first codeword when an FEF is not used and additional Li static information is included in the second codeword 15 when an FEF is used. Hence, the input information of the first codeword is constant in bit number and type. Main fields of Li configurable information and Li dynamic information of Part II listed in Table 405 are "MUM PLP" indicating the number of PLPs transmitted in a 20 (super)frame, "PLP ID" is an Identification (ID) specific to a PLP, "PLPCO" indicating the code rate of the PLP, "PLP MOD" indicating the modulation scheme of the PLP, "PLPFECTYPE" indicating an FEC type used for the PLP, PLPNUMBLOCKS indicating the number of FEC blocks included 25 in an interleaved frame of the current PLP, and "PLP START" indicating the start position of the PLP in the current PLP. FIG. 5 is a flowchart illustrating a method for transmitting control information in a transmitter in the wireless communication system according to an exemplary 30 embodiment of the present invention. Referring to FIG. 5, the transmitter generates P2 information (L1 pre-signaling information, Li static information, Li configurable information, and Li dynamic information) as control information for a current frame in 35 step 501. The transmitter generates a coded block as a first codeword (Part I) by LDPC-encoding the Li pre-signaling information and default Li static information having a fixed number of bits among the determined control information and transmits the first codeword in step 502. In step 503, the 40 transmitter determines whether the generated control information includes additional Li static information. In the absence of the additional Li static information, the transmitter generates a codeword being a coded block by LDPC-encoding the Li configurable information and Li dynamic information having a variable number of bits and transmits 5 the codeword in step 504. If the Li configurable information and Li dynamic information have a large number of bits, they can be transmitted in a plurality of code blocks, i.e. in a plurality of codewords. In the presence of the additional Li static information 10 in step 503, the transmitter generates a codeword by LDPC encoding the additional Li static information together with the Li configurable information and the Li dynamic information and transmits the codeword in step 505. If the sum of the Li configurable information and the Li dynamic 15 information is a large number of bits, they can be transmitted in a plurality of codewords. After step 504 or 505, the transmitter repeats the above operation for a next frame in step 506. FIG. 6 is a flowchart illustrating a method for 20 receiving control information in a receiver in the wireless communication system according to an embodiment of the present invention. Referring to FIG. 6, the receiver acquires Li pre signaling information and default Li static information by 25 decoding the coded block (Low Density Parity Check (LDPC) block) of a first codeword in a received current frame in accordance with predetermined subcarriers, code rate, and modulation scheme in step 601. In step 602, the receiver determines, based on the acquired information, whether a 30 plurality of RF channels or an FEF is used. The determination of step 602 is about whether additional Li static information exists. If additional Li static information does not exist in step 602, the receiver receives a second codeword of Part II in the current frame 35 using the positions of subcarriers, the code rate, and the modulation scheme of Part II acquired from the Li pre signaling information and acquires Li configurable information and Li dynamic information from the second codeword of Part II in step 603. If determining that the 40 additional Li static information exists in step 602, the receiver receives a second codeword of Part II in the current frame using the positions of subcarriers, the code rate, and the modulation scheme of Part II acquired from the Li pre-signaling information and acquires the additional Li static information, the Li configurable information, and the 5 Li dynamic information from the second codeword of Part II in step 604. In step 605, the receiver repeats the above operation for a next frame. FIG. 7 is a block diagram of the transmitter in the wireless communication system according to an embodiment of 10 the present invention. Referring to FIG. 7, a transmitter 700 includes a transmission data buffer 701, a scheduler 702, a control information generator 703, an LDPC encoder 704, a transmission part 705, and a controller 706. In accordance 15 with the present invention, control information, that is, physical layer signaling information transmitted from the transmitter 700 is divided into Li pre-signaling information with a fixed number of bits, and Li configurable information and Li dynamic information with a variable number of bits. 20 The Li variable information and the Li dynamic information are referred to as Li-post signaling information. The transmission data buffer 701 buffers service data (i.e. PLPs) to be transmitted on a plurality of broadcasting service channels, when a broadcasting service is provided in 25 the wireless communication system. The scheduler 702 performs a predetermined scheduling operation based on information about the buffered data received from the transmission data buffer 701. The scheduling operation involves determining the Li pre-signaling information, the 30 Li configurable information, and the Li dynamic information as control information to be transmitted in a frame. The control information generator 703 receives the result of the scheduling operation and generates field values for the Li pre-signaling information, the Li configurable information, 35 and the Li dynamic information that have been described in detail with reference to FIG. 4. The LDPC encoder 704 receives the control information from the control information generator 703, generates a coded block (LDPC block) from the signaling information with the fixed number 40 of bits and generates at least one coded block from the signaling information with the variable number of bits. The transmission part 705 transmits the LDPC blocks received from the LDPC encoder 704 according to predetermined subcarrier positions, code rate, and modulation scheme. The controller 705 provides overall control to the transmitter 5 700 in order to generate and transmit LDPC blocks in the method of FIG. 5. FIG. 8 is a block diagram of the receiver in the wireless communication system according to an embodiment of the present invention. 10 Referring to FIG. 8, a receiver 800 includes a control information receiver 801, an LDPC decoder 802, a control information analyzer 804, and a controller 803. The control information receiver 801 receives control information, that is, Li signaling information including Li pre-signaling 15 information, Li configurable information, and Li dynamic information according to predetermined subcarrier positions, code rate, and modulation scheme and demodulates the Li signaling information. The LDPC decoder 802 decodes the demodulated Li signaling information in the method described 20 in FIG. 6 and outputs the decoded information to the control information analyzer 804 which analyzes the decoded contol information. The controller 803 provides overall control to the receiver 800 to receive and decode LDPC blocks in the method of FIG. 6. 25 Embodiments of the present invention can also be embodied as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the 30 computer-readable recording medium include, but are not limited to, read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission through the Internet via wired or wireless 35 transmission paths). The computer-readable recording medium can also be distributed over network-coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion. Also, function programs, codes, and code segments for accomplishing the present 40 invention can be easily construed as within the scope of the invention by programmers skilled in the art to which the present invention pertains. While the invention has been shown and described with reference to certain embodiments of the present invention 5 thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents. 10 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, 15 i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims (15)

1. A method for transmitting control information in a communication system, comprising the steps of: 5 determining signaling information for a physical layer to be transmitted in a frame; generating at least one coded block from signaling information having a variable number of bits included in the signaling information for the physical layer; and 10 transmitting a frame including the at least one coded block, wherein the frame includes a coded block including other signaling information having a fixed number of bits required for receiving the signaling information having the variable 15 number of bits, wherein the signaling information having the variable number of bits includes frequency information about a radio frequency (RF) channel for transmitting at least one physical layer pipe (PLP). 20

2. The method of claim 1, wherein the frame includes service data and the signaling information having the variable number of bits includes information required for receiving the service data. 25

3. The method of claim 1, wherein the other signaling information having the fixed number of bits includes at least one among information about the number of RF channels, information indicating whether a further extension frame 30 (FEF) is used, information about a cell identifier (ID) , a network ID, and a system ID.

4. The method of claim 1, wherein the signaling information having the variable number of bits includes 35 information related to a further extension frame (FEF) reserved for future use.

5. The method of claim 1, wherein the signaling information having the variable number of bits includes 40 layer 1 (L1) configurable information having a lower probability for change in an upcoming frame and Li dynamic information having a high probability for change in every frame among the signaling information for the physical layer.

6. The method of claim 1, wherein the signaling information having the fixed number of bits includes layer 1 5 (L1) pre-signaling information that remains constant in the signaling information for the physical layer.

7. The method of claim 1, wherein the generation comprises generating the at least one coded block by using a low 10 density parity check (LDPC) coding scheme.

8. An apparatus for transmitting control information in a communication system, comprising: an encoder configured to encode received information in a 15 predetermined coding scheme; a transmitter configured to transmit a frame; and a controller configured to control the encoder to generate at least one coded block from signaling information having a variable number of bits included in signaling 20 information for a physical layer, and the transmitter to transmit a frame including the at least one coded block, wherein the frame includes a coded block including other signaling information having a fixed number of bits required for receiving the signaling information having the variable 25 number of bits, wherein the signaling information having the variable number of bits includes frequency information about a radio frequency (RF) channel for transmitting at least one physical layer pipe (PLP). 30

9. The apparatus of claim 8, wherein the controller generates the signaling information for the physical layer to be transmitted in the frame according to predetermined scheduling. 35

10. The apparatus of claim 8, wherein the frame includes service data and the signaling information having the variable number of bits includes information required for receiving the service data. 40

11. The apparatus of claim 8, wherein the other signaling information having the fixed number of bits includes at least one among information about the number of RF channels, information indicating whether a further extension frame (FEF) is used, information about a cell identifier (ID) , a network ID, and a system ID. 5

12. The apparatus of claim 8, wherein the signaling information having the variable number of bits includes information related to a further extension frame (FEF) reserved for future use. 10

13. The apparatus of claim 8, wherein the signaling information having the variable number of bits includes layer 1 (L1) configurable information having a lower probability for change in an upcoming frame and Li dynamic information having a high probability for change in every 15 frame among the signaling information for the physical layer.

14. The apparatus of claim 8, wherein the signaling information having the fixed number of bits includes layer 1 20 (L1) pre-signaling information that remains constant in the signaling information for the physical layer.

15. The apparatus of claim 8, wherein the encoder generates the at least one coded block by using a low density parity 25 check (LDPC) coding scheme.