WO2008156254A1 - Control information transmission and receiving in packet based mobile communication system - Google Patents

Control information transmission and receiving in packet based mobile communication system Download PDF

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Publication number
WO2008156254A1
WO2008156254A1 PCT/KR2008/003224 KR2008003224W WO2008156254A1 WO 2008156254 A1 WO2008156254 A1 WO 2008156254A1 KR 2008003224 W KR2008003224 W KR 2008003224W WO 2008156254 A1 WO2008156254 A1 WO 2008156254A1
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WO
WIPO (PCT)
Prior art keywords
information
control
mobile station
control channel
channel block
Prior art date
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PCT/KR2008/003224
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French (fr)
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WO2008156254A8 (en
Inventor
Kyoung-Seok Lee
Soo-Jung Jung
Jae-Heung Kim
Jung-Im Kim
Byung-Han Ryu
Original Assignee
Electronics And Telecommunications Research Institute
Samsung Electronics.Co., Ltd.
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Application filed by Electronics And Telecommunications Research Institute, Samsung Electronics.Co., Ltd. filed Critical Electronics And Telecommunications Research Institute
Publication of WO2008156254A1 publication Critical patent/WO2008156254A1/en
Publication of WO2008156254A8 publication Critical patent/WO2008156254A8/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0072—Error control for data other than payload data, e.g. control data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/04—Error control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0028—Formatting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0061—Error detection codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery

Definitions

  • the present invention relates to a method for transmitting/receiving control information in a packet- based mobile communication system; and, more particularly, to a method for transmitting/receiving control information needed between Medium Access Control (MAC) layers of a base station and a mobile station by using a control channel block in a packet-based mobile communication system, which is under discussion for standardization, while minimizing the use of a control channel block.
  • MAC Medium Access Control
  • next-generation packet-based mobile communication system will adopt Frequency Division Duplex (FDD) for wireless transmission, Orthogonal Frequency Division Multiple Access (OFDMA) scheme for downlink transmission, and Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme for uplink transmission.
  • FDD Frequency Division Duplex
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single Carrier Frequency Division Multiple Access
  • a typical mobile communication system includes a base station forming a cell and a mobile station used by a user, and a plurality of mobile stations transmit/receive packet data to/from the base station through a radio channel.
  • Fig. 1 shows a typical packet-based mobile communication system. Only a base station 10 and a mobile station 20 are presented in Fig. 1.
  • the base station 10 and the mobile station 20 transmits/receives data and control information through radio channels, which are divided into downlink and uplink.
  • Downlink data enter a downlink buffer 11.
  • a downlink scheduler 12 allocates radio resources to each mobile station, and the data entering the downlink buffer 11 are transmitted to the mobile station 20 by using radio resources allocated by the downlink scheduler 12. Since the downlink scheduler dynamically allocates radio resources of the packet-based mobile communication, control information needed to demodulate a data channel, which is Physical Downlink Shared Channel (PDSCH), is transmitted through a Physical Downlink Control Channel (PDCCH) .
  • PDSCH Physical Downlink Shared Channel
  • uplink data are transmitted as follows.
  • an uplink scheduler 13 in the base station 10 allocates radio resources to be used for transmitting uplink data.
  • the mobile station 20 forms an uplink data channel, which is a Physical Uplink Shared Channel (PUSCH), and transmits the data inputted to an uplink buffer 21 by using uplink radio resource information transmitted from the base station through the control channel, which is PDCCH.
  • An uplink control channel which is Physical Uplink Control Channel (PUCCH), is used for transmitting uplink buffer status information and downlink retransmission information.
  • PUCCH Physical Uplink Control Channel
  • a physical channel used in a packet-based mobile communication system will be briefly described herein for understanding of the present invention.
  • Downlink channels related to data transmission are as follows.
  • a Physical Downlink Shared Channel (PDSCH) is a physical channel for transmitting downlink data.
  • the PDSCH is allocated to resource blocks (RB) shown in Fig. 2 and transmits data.
  • RB resource blocks
  • a scheduler of a base station may allocate a plurality of resource blocks to one mobile station.
  • OFDM symbols 32 may be allocated to the rest of the resource blocks except the PDCCH region 34. In other words, the less PDCCH blocks are used, the more data can be transmitted through the radio resource blocks.
  • the PDCCH is a physical channel for transmitting control signals needed for data reception to a mobile station.
  • the PDCCH is allocated to the PDCCH blocks 33 shown in Fig. 2 and transmits signals.
  • the PDCCH includes control information needed for receiving data through the PDSCH and includes control information for the PUSCH. Because an uplink packet scheduler managing uplink data transmission/reception of the packet-based mobile communication system uses a central management method in the base station, control information on the PUSCH is transmitted/received through the PDCCH. To be specific, the uplink packet scheduler of the base station manages uplink radio resources of all mobile stations, such as radio resource allocation and collection. Uplink channels related to data transmission are as follows.
  • a PUSCH is a physical channel for transmitting uplink data and it is similar to the PDSCH in functions. Control information related to the PUSCH is transmitted from the base station through a PDCCH.
  • a PUCCH is a physical channel for transmitting control information from a mobile station to a base station and it uses radio resources independent from the PUSCH. Control informations included in the PUCCH include downlink channel status information, downlink retransmission information, and uplink buffer status information.
  • Fig. 2 illustrates a typical structure of a downlink radio channel in a packet-based mobile communication system.
  • the drawing shows a radio channel structure of an LTE system, which is under discussion by the 3GPP.
  • the packet-based mobile communication system transmits data in parallel using a plurality of radio carriers for communication.
  • OFDMA Orthogonal Frequency Division Multiple Access
  • the packet-based mobile communication system transmits data using a plurality of subcarriers, and it manages the subcarriers within a system bandwidth, e.g., 20 MHz, on a subcarrier group 31 basis on a frequency axis.
  • a system bandwidth e.g. 20 MHz
  • TTI Transmit Time Interval
  • one TTI may include 14 OFDM symbols according to temporal length of an OFDM symbol.
  • radio resources are divided into resource blocks (RBs) and one resource block (RB) is a resource allocation unit obtained by binding OFDM symbols according to a subcarrier group 31 and a TTI unit from the perspective of the frequency axis and time axis.
  • Resource blocks are what a radio resource is divided into pieces of an identical size so that the scheduler of the base station can easily allocate data.
  • a resource block is of a size ⁇ 12 subcarriers x TTI (e.g., 1 msec)'.
  • the amount of data that can be allocated to a resource block becomes different due to adaptive modulation. That is, the amount of data varies according to the type of a modulation scheme applied to symbols, such as Quadrature Phase Shift Keying (QPSK), 16QAM, 64QAM and the like.
  • QPSK Quadrature Phase Shift Keying
  • 16QAM 16QAM
  • 64QAM 64QAM
  • the uplink uses SC-FDMA scheme. Since the features of the present invention are the same as described referring to Fig. 2, the radio channel structure of the uplink will not be described herein.
  • the base station (which is a transmitter) transmits control information to a mobile station through a PDCCH so that the mobile station (which is a receiver) demodulates data.
  • the PDCCH uses subcarriers of entire system bandwidth on the frequency axis and uses up to three OFDM symbols within a TTI on the time axis.
  • the PDCCH can use up to three symbols of the resource blocks as a PDCCH region.
  • the PDCCH region distributed over the entire bandwidth of the system is divided into a plurality of PDCCH resource blocks 33 to transmit control information to each mobile station. Referring to Fig.
  • one PDCCH resource block is formed of three OFDM symbols which belong to two resource blocks, and one control information may be formed of 84 symbols, which are 'two resource blocks X 14 subcarriers X 3 OFDM symbols.
  • control information of a relatively small size is allocated to a PDSCH and transmitted in the packet-based mobile communication system, the data channel is used wastefully and the PDCCH for controlling the data channel comes to be used wastefully as well.
  • control information required between the Medium Access Control (MAC) layers of a base station and a mobile station has a size as small as from one bit to thousands of bits.
  • MAC Medium Access Control
  • An embodiment of the present invention is directed to providing a method for transmitting/receiving control information needed between the Medium Access Control
  • MAC MAC layers of a base station and a mobile station by using control channel blocks while minimizing consumption of the control channel blocks in a packet-based mobile communication system.
  • a method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers which includes: a) forming a control channel block including control information for controlling the mobile station and identification (ID) information for identifying the control information transmitted to the mobile station; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
  • ID identification
  • a method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers which includes: a) forming a control channel block not by including a flag field in a control channel block but by allocating ID information for identifying control information transmitted to the mobile station to a specific field in a control information region which constitute the control channel block and allocating the control information for controlling the mobile station to the control information region; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
  • control channel block includes Cyclic Redundancy Check (CRC) information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
  • CRC Cyclic Redundancy Check
  • a ⁇ 0' value is allocated to a transport block (TB) field indicating size information of the resource block included in the control information region in said a) forming a control channel block, and the TB field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field.
  • TB transport block
  • a numerical figure that is not the number of validly allocated resource blocks is allocated to a resource block location information field in said a) forming a control channel block, and the resource block location information field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field.
  • the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or discontinuous transmission/reception information for low-power-consuming control.
  • MAC Medium Access Control
  • a method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers which includes: a) receiving a control channel block through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in a control information region of the control channel block.
  • a method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers which includes: a) receiving a control channel block without a flag field through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of a specific field of a predetermined control information region in the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in the control information region of the control channel block.
  • the information included in the control channel block is recognized as control information for controlling the mobile station.
  • the information included in the control channel block is recognized as control information for controlling the mobile station.
  • the present invention can minimize wasteful consumption of radio resources of a data channel by directly transmitting control information needed from MAC layers from a base station through a control channel. Also, since the present invention does not use a flag field and identifies control information in control channel blocks by using a value generally not used among modulation/demodulation information of the data channel
  • Fig. 1 shows a typical packet-based mobile communication system.
  • Fig. 2 shows a structure of a downlink radio channel in the packet-based mobile communication system.
  • Fig. 3 illustrates a structure of a control channel block in accordance with an embodiment of the present invention.
  • Fig. 4 describes a structure of a control channel block based on each MAC information in accordance with an embodiment of the present invention.
  • PDCCH Physical Downlink Control Channel
  • control information e.g., control information required by a Medium Access Control (MAC) layer
  • control information includes control information needed between MAC layers of a base station and a mobile station, and control information needed by each layer and as small as 1 bit to scores of bits.
  • MAC information will be taken as an example of the control information but the present invention is not limited to it.
  • Fig. 3 illustrates a structure of a control channel block and a process of transmitting control information in accordance with an embodiment of the present invention.
  • the PDCCH structure includes a control channel structure suggested in the present invention.
  • a PDCCH region 101 includes a plurality of control channel blocks CBl to CBn, and each control channel block includes control information for uplink or downlink data channel of a mobile station.
  • a control channel block CBl includes downlink data channel information of a mobile station and a control channel block CB2 includes uplink data channel information of a mobile station.
  • Structure information of a general control channel defined by the LTE includes the following information.
  • a control channel block includes modulation/demodulation information of a downlink or uplink data channel.
  • the modulation/demodulation information of the data channels includes size information of a radio resource block (such as, a payload size is of 20 bits) , location information of a radio resource block (e.g., RB5 and RB6) , channel coding information of data (e.g., turbo coding scheme and modulation data rate of 1/3) , adaptive modulation information (e.g., QPSK, 16QAM, and 64QAM) , antenna information (e.g., information supporting Multiple Input Multiple Output (MIMO) operation) , and retransmission information (e.g., information supporting Hybrid Automatic Retransmit reQuest (HARQ) operation) .
  • MIMO Multiple Input Multiple Output
  • retransmission information e.g., information supporting Hybrid Automatic Retransmit reQuest (HARQ)
  • Cyclic Redundancy Check (CRC) information which is an error correction code of a control channel block and constitutes a general control channel block (CB) defined by the LTE.
  • CRC is masked using a cell-radio network temporary identifier (C-RNTI). Accordingly, a designated mobile station does not have a CRC error when a control channel block is demodulated and thus only the designated mobile station can demodulate the control information.
  • C-RNTI cell-radio network temporary identifier
  • a designated mobile station does not have a CRC error when a control channel block is demodulated and thus only the designated mobile station can demodulate the control information.
  • the control channel block includes data channel information and CRC information.
  • a flag field 103 may be added to a general control channel block.
  • the flag field 103 is added to indicate control information of diverse forms.
  • a control channel block CBl includes the flag field 103, downlink data channel information 104 of a mobile station 1, which is also referred to as user equipment UEl, and CRC information 105.
  • a control channel block CB2 includes a flag field, uplink data channel information of a mobile station UB2, and CRC information.
  • a mobile station analyzes a flag field and identifies uplink information or downlink information when it receives and demodulates a control channel block.
  • a flag field wastes radio resources because all control channel blocks should include flags of a predetermined size, such as 1 to 4 bits.
  • radio resources are wasted because the flags of the same size should be maintained all the time not in a channel for transmitting MAC information but in a control channel for transmitting data channel modulation/demodulation information .
  • the present invention suggests using a value of a field which is not generally used among the modulation/demodulation information of a data channel as an identifier for identifying the form of a control channel.
  • a certain value e.g., ⁇ 0' value
  • a control channel block CB3 106 does not include an additional flag field and it includes only a control information region and 16-bit CRC information 110.
  • the control information region includes a 4-bit TB field 107, a 2-bit sub-index field 108, and an 8-bit specific control information field 109.
  • the base station when transmitting MAC information through a control channel block, the base station sets up the TB field 107 to be ⁇ 0', indicates that subsequent control information is MAC information, and allocates the MAC information to specific control information.
  • the mobile station demodulates the control channel block and when the value of the TB field is ⁇ 0', it recognizes that the subsequent control information is MAC information and executes MAC by using the MAC information allocated to the specific control information field.
  • MAC information may be indicated in the following method without using a flag field additionally.
  • a system of a 10 MHz bandwidth uses up to 50 data resource blocks.
  • information is not data channel modulation/demodulation information but MAC information by indicating a resource block location information field not by the number of valid resource blocks but by 51.
  • the base station transmits MAC information through a control channel block, it allocates a number that is not the number of the validly allocated resource blocks to the resource block location information field to indicate control information included in the control channel block.
  • the mobile station demodulates the control channel block, recognizes the control information included subsequent fields as MAC information when the numerical figure allocated to the resource block position information field is not the number of validly allocated resource blocks, and executes MAC based on the MAC information.
  • Fig. 4 describes a structure of MAC information in accordance with an embodiment of the present invention.
  • the entire size of PDCCH may be variable.
  • detail information of a control channel block may include a TB field indicating resource block size information, a sub-index field, a specific control information field (which is a control information payload field), and a CRC field.
  • the TB field indicates the size of data that can be allocated to a related data channel. It is possible to indicate information included in a control channel block as MAC information by allocating a specific value (e.g., ⁇ 0') to the TB field.
  • the TB field has the same size as a TB field used in general PDCCH.
  • the sub-index field indicates the form of the MAC information.
  • the size of the sub-index may indicate the type of the MAC information.
  • the specific control information field (which is a control information payload field) includes detail information of each MAC information identified by the sub-index.
  • the MAC information is a Timing Advance (TA) control information
  • the mobile station may indicate information related to an uplink channel of the mobile station, and it may store a random access preamble index.
  • the MAC information is a discontinuous reception (DRX) control information for power-saving operation
  • the mobile station may include a DRX mode and a DRX period.
  • the base station may direct the mobile station to change its mode in the requested mode through a control channel.
  • the method of the present invention described above may be programmed for a computer.
  • Codes and code segments constituting the computer program may be easily inferred by a computer programmer of ordinary skill in the art to which the present invention pertains.
  • the computer program may be stored in a computer-readable recording medium, i.e., data storage, and it may be read and executed by a computer to realize the method of the present invention.
  • the recording medium includes all types of computer-readable recording media.
  • the present invention a technology for transmitting control information needed between Medium Access Control (MAC) layers of a base station and a mobile station by using a control channel block in a packet-based mobile communication system, which is under discussion for standardization, while minimizing the use of a control channel block.
  • MAC Medium Access Control

Abstract

Provided is a method for transmitting/receiving control information needed between Medium Access Control (MAC) layers of a base station and a mobile station by using a control channel block in a packet-based mobile communication system, which is under discussion for standardization, while minimizing the use of a control channel block. The method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, which includes: a) forming a control channel block including control information for controlling the mobile station and identification (ID) information for identifying the control information transmitted to the mobile station; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.

Description

DESCRIPTION
CONTROL INFORMATION TRANSMISSION AND RECEIVING IN PACKET BASED MOBILE COMMUNICATION SYSTEM
TECHNICAL FIELD
The present invention relates to a method for transmitting/receiving control information in a packet- based mobile communication system; and, more particularly, to a method for transmitting/receiving control information needed between Medium Access Control (MAC) layers of a base station and a mobile station by using a control channel block in a packet-based mobile communication system, which is under discussion for standardization, while minimizing the use of a control channel block.
This work was supported by the IT R&D program of MIC/IITA [2005-S-404-13, "Research & Development of Radio Transmission Technology for 3G evolution"].
BACKGROUND ART
3rd Generation Partnership Project (3GPP), which is a standardization organization for asynchronous mobile communication is actively working on Long Term Evolution (LTE) standardization to develop a next-generation mobile communication system specification. The next-generation packet-based mobile communication system will adopt Frequency Division Duplex (FDD) for wireless transmission, Orthogonal Frequency Division Multiple Access (OFDMA) scheme for downlink transmission, and Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme for uplink transmission.
A typical mobile communication system includes a base station forming a cell and a mobile station used by a user, and a plurality of mobile stations transmit/receive packet data to/from the base station through a radio channel.
Fig. 1 shows a typical packet-based mobile communication system. Only a base station 10 and a mobile station 20 are presented in Fig. 1. The base station 10 and the mobile station 20 transmits/receives data and control information through radio channels, which are divided into downlink and uplink. Downlink data enter a downlink buffer 11. A downlink scheduler 12 allocates radio resources to each mobile station, and the data entering the downlink buffer 11 are transmitted to the mobile station 20 by using radio resources allocated by the downlink scheduler 12. Since the downlink scheduler dynamically allocates radio resources of the packet-based mobile communication, control information needed to demodulate a data channel, which is Physical Downlink Shared Channel (PDSCH), is transmitted through a Physical Downlink Control Channel (PDCCH) .
Meanwhile, uplink data are transmitted as follows. First, an uplink scheduler 13 in the base station 10 allocates radio resources to be used for transmitting uplink data. The mobile station 20 forms an uplink data channel, which is a Physical Uplink Shared Channel (PUSCH), and transmits the data inputted to an uplink buffer 21 by using uplink radio resource information transmitted from the base station through the control channel, which is PDCCH. An uplink control channel, which is Physical Uplink Control Channel (PUCCH), is used for transmitting uplink buffer status information and downlink retransmission information.
A physical channel used in a packet-based mobile communication system will be briefly described herein for understanding of the present invention. Downlink channels related to data transmission are as follows. A Physical Downlink Shared Channel (PDSCH) is a physical channel for transmitting downlink data. The PDSCH is allocated to resource blocks (RB) shown in Fig. 2 and transmits data. Generally, a scheduler of a base station may allocate a plurality of resource blocks to one mobile station. Also, when a PDCCH region 34 is small in the radio resource blocks of Fig. 2, OFDM symbols 32 may be allocated to the rest of the resource blocks except the PDCCH region 34. In other words, the less PDCCH blocks are used, the more data can be transmitted through the radio resource blocks.
The PDCCH is a physical channel for transmitting control signals needed for data reception to a mobile station. The PDCCH is allocated to the PDCCH blocks 33 shown in Fig. 2 and transmits signals. The PDCCH includes control information needed for receiving data through the PDSCH and includes control information for the PUSCH. Because an uplink packet scheduler managing uplink data transmission/reception of the packet-based mobile communication system uses a central management method in the base station, control information on the PUSCH is transmitted/received through the PDCCH. To be specific, the uplink packet scheduler of the base station manages uplink radio resources of all mobile stations, such as radio resource allocation and collection. Uplink channels related to data transmission are as follows. A PUSCH is a physical channel for transmitting uplink data and it is similar to the PDSCH in functions. Control information related to the PUSCH is transmitted from the base station through a PDCCH. A PUCCH is a physical channel for transmitting control information from a mobile station to a base station and it uses radio resources independent from the PUSCH. Control informations included in the PUCCH include downlink channel status information, downlink retransmission information, and uplink buffer status information.
Fig. 2 illustrates a typical structure of a downlink radio channel in a packet-based mobile communication system. The drawing shows a radio channel structure of an LTE system, which is under discussion by the 3GPP.
The packet-based mobile communication system transmits data in parallel using a plurality of radio carriers for communication. Herein, it is assumed that the packet-based mobile communication system adopts Orthogonal Frequency Division Multiple Access (OFDMA) scheme .
The packet-based mobile communication system transmits data using a plurality of subcarriers, and it manages the subcarriers within a system bandwidth, e.g., 20 MHz, on a subcarrier group 31 basis on a frequency axis. On a time axis, it groups OFDM symbols 32 on the basis of Transmit Time Interval (TTI), e.g., 1 msec for management. For instance, one TTI may include 14 OFDM symbols according to temporal length of an OFDM symbol. Thus, radio resources are divided into resource blocks (RBs) and one resource block (RB) is a resource allocation unit obtained by binding OFDM symbols according to a subcarrier group 31 and a TTI unit from the perspective of the frequency axis and time axis.
Resource blocks are what a radio resource is divided into pieces of an identical size so that the scheduler of the base station can easily allocate data. For example, a resource block is of a size Λ12 subcarriers x TTI (e.g., 1 msec)'. The amount of data that can be allocated to a resource block becomes different due to adaptive modulation. That is, the amount of data varies according to the type of a modulation scheme applied to symbols, such as Quadrature Phase Shift Keying (QPSK), 16QAM, 64QAM and the like. Also, when data are allocated to resource blocks, a modulation scheme needed for channel coding and wireless communication is applied. Thus, the data amount of the radio resource blocks varies. In the packet-based mobile communication system, the uplink uses SC-FDMA scheme. Since the features of the present invention are the same as described referring to Fig. 2, the radio channel structure of the uplink will not be described herein.
From the perspective of operating a radio channel, the base station (which is a transmitter) transmits control information to a mobile station through a PDCCH so that the mobile station (which is a receiver) demodulates data. The PDCCH uses subcarriers of entire system bandwidth on the frequency axis and uses up to three OFDM symbols within a TTI on the time axis. The PDCCH can use up to three symbols of the resource blocks as a PDCCH region. The PDCCH region distributed over the entire bandwidth of the system is divided into a plurality of PDCCH resource blocks 33 to transmit control information to each mobile station. Referring to Fig. 2, one PDCCH resource block is formed of three OFDM symbols which belong to two resource blocks, and one control information may be formed of 84 symbols, which are 'two resource blocks X 14 subcarriers X 3 OFDM symbols.' When control information of a relatively small size is allocated to a PDSCH and transmitted in the packet-based mobile communication system, the data channel is used wastefully and the PDCCH for controlling the data channel comes to be used wastefully as well. Particularly, control information required between the Medium Access Control (MAC) layers of a base station and a mobile station has a size as small as from one bit to thousands of bits. Because it is inefficient to allocate such small control information to a data channel and transmit it, it is required to develop a method of directly allocating the small control information to a PDCCH and transmitting the control information. Also, when diverse forms of control informations are transmitted through the PDCCH, flags of a predetermined size are needed to identify control informations, individually. The flags also waste the PDCCH resources. Therefore, it is required to develop a technology for transmitting control information through a control channel, which is PDCCH, while minimizing consumption of control channel resources.
DISCLOSURE TECHNICAL PROBLEM
An embodiment of the present invention is directed to providing a method for transmitting/receiving control information needed between the Medium Access Control
(MAC) layers of a base station and a mobile station by using control channel blocks while minimizing consumption of the control channel blocks in a packet-based mobile communication system.
Other objects and advantages of the present invention can be understood by the following description, and become apparent with reference to the embodiments of the present invention. Also, it is obvious to those skilled in the art of the present invention that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof.
TECHNICAL SOLUTION
In accordance with an aspect of the present invention, there is provided a method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, which includes: a) forming a control channel block including control information for controlling the mobile station and identification (ID) information for identifying the control information transmitted to the mobile station; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
In accordance with another aspect of the present invention, there is provided a method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, which includes: a) forming a control channel block not by including a flag field in a control channel block but by allocating ID information for identifying control information transmitted to the mobile station to a specific field in a control information region which constitute the control channel block and allocating the control information for controlling the mobile station to the control information region; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
Herein, the control channel block includes Cyclic Redundancy Check (CRC) information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
Herein, a Λ0' value is allocated to a transport block (TB) field indicating size information of the resource block included in the control information region in said a) forming a control channel block, and the TB field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field.
Herein, a numerical figure that is not the number of validly allocated resource blocks is allocated to a resource block location information field in said a) forming a control channel block, and the resource block location information field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field. Herein, the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or discontinuous transmission/reception information for low-power-consuming control. In accordance with another aspect of the present invention, there is provided a method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, which includes: a) receiving a control channel block through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in a control information region of the control channel block.
In accordance with another aspect of the present invention, there is provided a method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, which includes: a) receiving a control channel block without a flag field through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of a specific field of a predetermined control information region in the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in the control information region of the control channel block. Herein, when a λ0' value is allocated to a TB field indicating size information of a resource block included in the control information region in said c) recognizing a type of the control information, the information included in the control channel block is recognized as control information for controlling the mobile station.
Herein, when a numerical figure that is not the number of validly allocated resource blocks is allocated to a resource block location information field in said c) recognizing a type of the control information, the information included in the control channel block is recognized as control information for controlling the mobile station.
ADVANTAGEOUS EFFECTS
The present invention can minimize wasteful consumption of radio resources of a data channel by directly transmitting control information needed from MAC layers from a base station through a control channel. Also, since the present invention does not use a flag field and identifies control information in control channel blocks by using a value generally not used among modulation/demodulation information of the data channel
(for example, a value making the data size Λ0' to a transport block (TB) ) , it is possible to minimize wasteful consumption of radio resources of a radio channel .
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a typical packet-based mobile communication system.
Fig. 2 shows a structure of a downlink radio channel in the packet-based mobile communication system.
Fig. 3 illustrates a structure of a control channel block in accordance with an embodiment of the present invention.
Fig. 4 describes a structure of a control channel block based on each MAC information in accordance with an embodiment of the present invention.
BEST MODE FOR THE INVENTION
The advantages, features and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. When it is considered that detailed description on a related art may obscure a point of the present invention, the description will not be provided herein. Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.
Generally, a Physical Downlink Control Channel
(PDCCH) is a channel used to transmit modulation/demodulation information of a Physical
Downlink Shared Channel (PDSCH) and a Physical Uplink Shared Channel (PUSCH) to a mobile station. The present invention provides a method for efficiently transmitting control information (e.g., control information required by a Medium Access Control (MAC) layer) other than modulation/demodulation information through the PDCCH. Herein, control information includes control information needed between MAC layers of a base station and a mobile station, and control information needed by each layer and as small as 1 bit to scores of bits. In the following description, MAC information will be taken as an example of the control information but the present invention is not limited to it.
Fig. 3 illustrates a structure of a control channel block and a process of transmitting control information in accordance with an embodiment of the present invention. Referring to Fig. 3, a structure of a PDCCH generally used in a packet-based mobile communication system is briefly illustrated. The PDCCH structure includes a control channel structure suggested in the present invention. A PDCCH region 101 includes a plurality of control channel blocks CBl to CBn, and each control channel block includes control information for uplink or downlink data channel of a mobile station. Referring to Fig. 3, a control channel block CBl includes downlink data channel information of a mobile station and a control channel block CB2 includes uplink data channel information of a mobile station.
Structure information of a general control channel defined by the LTE includes the following information. First, a control channel block includes modulation/demodulation information of a downlink or uplink data channel. The modulation/demodulation information of the data channels includes size information of a radio resource block (such as, a payload size is of 20 bits) , location information of a radio resource block (e.g., RB5 and RB6) , channel coding information of data (e.g., turbo coding scheme and modulation data rate of 1/3) , adaptive modulation information (e.g., QPSK, 16QAM, and 64QAM) , antenna information (e.g., information supporting Multiple Input Multiple Output (MIMO) operation) , and retransmission information (e.g., information supporting Hybrid Automatic Retransmit reQuest (HARQ) operation) .
Next, there is 16-bit Cyclic Redundancy Check (CRC) information, which is an error correction code of a control channel block and constitutes a general control channel block (CB) defined by the LTE. CRC is masked using a cell-radio network temporary identifier (C-RNTI). Accordingly, a designated mobile station does not have a CRC error when a control channel block is demodulated and thus only the designated mobile station can demodulate the control information. When a base station forms uplink or downlink transmission information in a control channel block, which is shown in Fig. 3, the control channel block includes data channel information and CRC information.
Referring to Fig. 2, a flag field 103 may be added to a general control channel block. The flag field 103 is added to indicate control information of diverse forms. In Fig. 3, a control channel block CBl includes the flag field 103, downlink data channel information 104 of a mobile station 1, which is also referred to as user equipment UEl, and CRC information 105. Also, a control channel block CB2 includes a flag field, uplink data channel information of a mobile station UB2, and CRC information.
A mobile station analyzes a flag field and identifies uplink information or downlink information when it receives and demodulates a control channel block. However, using a flag field wastes radio resources because all control channel blocks should include flags of a predetermined size, such as 1 to 4 bits. Particularly, radio resources are wasted because the flags of the same size should be maintained all the time not in a channel for transmitting MAC information but in a control channel for transmitting data channel modulation/demodulation information .
To solve the problems, the present invention suggests using a value of a field which is not generally used among the modulation/demodulation information of a data channel as an identifier for identifying the form of a control channel.
For example, a value making data size Λ0' in a field for indicating size information of a resource block (for example, a value of a transport block (TB) = 0) is not used when modulation/demodulation of a data channel is indicated. Therefore, if a certain value (e.g., λ0' value) is allocated to a TB field 107, it is possible to identify the form of control information. Accordingly, when the value of the TB field is λ0', the mobile station recognizes that the subsequent information is MAC information for controlling the mobile station.
Referring to Fig. 3, a control channel block CB3 106 does not include an additional flag field and it includes only a control information region and 16-bit CRC information 110. The control information region includes a 4-bit TB field 107, a 2-bit sub-index field 108, and an 8-bit specific control information field 109.
Accordingly, when transmitting MAC information through a control channel block, the base station sets up the TB field 107 to be λ0', indicates that subsequent control information is MAC information, and allocates the MAC information to specific control information.
The mobile station demodulates the control channel block and when the value of the TB field is λ0', it recognizes that the subsequent control information is MAC information and executes MAC by using the MAC information allocated to the specific control information field.
Meanwhile, MAC information may be indicated in the following method without using a flag field additionally.
Generally, a system of a 10 MHz bandwidth uses up to 50 data resource blocks. Thus, it is possible to indicate that information is not data channel modulation/demodulation information but MAC information by indicating a resource block location information field not by the number of valid resource blocks but by 51. In other words, when the base station transmits MAC information through a control channel block, it allocates a number that is not the number of the validly allocated resource blocks to the resource block location information field to indicate control information included in the control channel block. Then, the mobile station demodulates the control channel block, recognizes the control information included subsequent fields as MAC information when the numerical figure allocated to the resource block position information field is not the number of validly allocated resource blocks, and executes MAC based on the MAC information.
Fig. 4 describes a structure of MAC information in accordance with an embodiment of the present invention. The entire size of PDCCH may be variable. As illustrated in Fig. 4, detail information of a control channel block may include a TB field indicating resource block size information, a sub-index field, a specific control information field (which is a control information payload field), and a CRC field.
The TB field indicates the size of data that can be allocated to a related data channel. It is possible to indicate information included in a control channel block as MAC information by allocating a specific value (e.g., λ0') to the TB field. The TB field has the same size as a TB field used in general PDCCH.
The sub-index field indicates the form of the MAC information. The size of the sub-index may indicate the type of the MAC information.
The specific control information field (which is a control information payload field) includes detail information of each MAC information identified by the sub-index. When the MAC information is a Timing Advance (TA) control information, the mobile station may indicate information related to an uplink channel of the mobile station, and it may store a random access preamble index. Also, when the MAC information is a discontinuous reception (DRX) control information for power-saving operation, the mobile station may include a DRX mode and a DRX period. When the mobile station decreases or increases its DRX period, the base station may direct the mobile station to change its mode in the requested mode through a control channel. The method of the present invention described above may be programmed for a computer. Codes and code segments constituting the computer program may be easily inferred by a computer programmer of ordinary skill in the art to which the present invention pertains. The computer program may be stored in a computer-readable recording medium, i.e., data storage, and it may be read and executed by a computer to realize the method of the present invention. The recording medium includes all types of computer-readable recording media. While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
INDUSTRIAL APPLICABILITY
The present invention a technology for transmitting control information needed between Medium Access Control (MAC) layers of a base station and a mobile station by using a control channel block in a packet-based mobile communication system, which is under discussion for standardization, while minimizing the use of a control channel block.

Claims

WHAT IS CLAIMED IS
1. A method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, comprising: a) forming a control channel block including control information for controlling the mobile station and identification (ID) information for identifying the control information transmitted to the mobile station; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
2. The method of claim 1, wherein the control channel block includes Cyclic Redundancy Check (CRC) information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
3. The method of claim 2, wherein the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or low-power-consuming control.
4. A method for transmitting control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, comprising: a) forming a control channel block not by including a flag field in a control channel block but by allocating identification (ID) information for identifying control information transmitted to the mobile station to a specific field in a control information region which constitute the control channel block and allocating the control information for controlling the mobile station to the control information region; and b) coding the control channel block and transmitting the coded control channel block to the mobile station.
5. The method of claim 4, wherein the control channel block includes CRC information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
6. The method of claim 5, wherein a λ0' value is allocated to a transport block (TB) field indicating size information of the resource block included in the control information region in said a) forming a control channel block, and the TB field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field.
7. The method of claim 5, wherein a numerical figure that is not the number of validly allocated resource blocks is allocated to a resource block location information field in said a) forming a control channel block, and the resource block location information field value is used as ID information for identifying the control information transmitted to the mobile station without a flag field.
8. The method of claim 5, wherein the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or discontinuous transmission/reception information for low-power- consuming control.
9. A method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, comprising : a) receiving a control channel block through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in a control information region of the control channel block.
10. The method of claim 9, wherein the control channel block includes Cyclic Redundancy Check (CRC) information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
11. The method of claim 10, wherein the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or discontinuous transmission/reception information for low-power- consuming control.
12. A method for receiving control information for controlling a mobile station in a packet-based mobile communication system with uplink and downlink schedulers, comprising : a) receiving a control channel block without a flag field through a control channel from a base station; b) demodulating the received control channel block; c) recognizing a type of the control information by detecting ID information for identifying control information transmitted to the mobile station out of a specific field of a predetermined control information region in the demodulated control channel block; and d) upon recognition of the type of the control information, acquiring the control information included in the control information region of the control channel block.
13. The method of claim 12, wherein the control channel block includes Cyclic Redundancy Check (CRC) information, and the CRC information is masked using an identifier of a specific mobile station so that only the specific mobile station decodes the control channel block.
14. The method of claim 13, wherein when a λ0' value is allocated to a TB field indicating size information of a resource block included in the control information region in said c) recognizing a type of the control information, the information included in the control channel block is recognized as control information for controlling the mobile station.
15. The method of claim 13, wherein when a numerical figure that is not the number of validly allocated resource blocks is allocated to a resource block location information field in said c) recognizing a type of the control information, the information included in the control channel block is recognized as control information for controlling the mobile station.
16. The method of claim 13, wherein the control information for controlling the mobile station is Medium Access Control (MAC) information, which includes timing adjustment information or discontinuous transmission/reception information for low-power- consuming control.
PCT/KR2008/003224 2007-06-18 2008-06-10 Control information transmission and receiving in packet based mobile communication system WO2008156254A1 (en)

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