JP2010206811A - Transmission method of control channel information, and base station and user terminal using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, in transmission to which MIMO is applied, the number of variable parameters increases, resulting in increase of the number of information bits required for the control channel; and that pieces of control channel information increases in proportion to the number of users when the number of simultaneous multiple users increases in one frame. <P>SOLUTION: In a transmission method of control channel information for performing adaptive coding modulation, a transmission side performs error correction coding of the control channel information at a fixed coding rate; modulates the control channel information having been subjected to the error correction coding through a prescribed modulation scheme, and transmits it; and performs thinning out or repetition of codes to the signals having been subjected to the error correcting coding in accordance with presence or absence of application of Multi-Input Multi-Output (MIMO) before the modulation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control channel information transmission method, and a base station and user terminal using the same.

  In the third generation mobile communication system, adaptive radio links such as adaptive modulation / demodulation, HARQ (Hybrid Automatic Repeat reQuest), and scheduling are used to increase the transmission efficiency of data packets.

  The adaptive radio link control is performed using an individual or shared control channel, and notifies each user terminal of link parameters used in a data channel transmitted almost simultaneously with the control channel.

  For example, in the case of an adaptive coding and modulation (AMC) system, the control channel transmits information such as a data channel modulation system and a coding rate. In the case of HARQ, the control channel transmits information such as the packet number of the packet transmitted on the data channel and the number of retransmissions. In the case of scheduling, the control channel transmits information such as a user ID.

  In HSDPA (High Speed Downlink Packet Access) standardized by 3GPP (Third Generation Partnership Protocol) for the third generation mobile communication system, as described in Non-Patent Document 1, HS-SCCH (Shared Control) is used. Control information as shown in Table 1 is transmitted using a common control channel called “Channel for HS-DSCH”.

  Further, in the above HSDPA, in FIG. 1 showing the relationship between the radio environment and the transmission rate, in the case of the AMC system, when the propagation state is good in the change of the radio environment I (when exceeding the threshold level TH), the modulation system is set to 16 The coding rate is increased as QAM (Quadrature Amplitude Modulation), and high-speed data transmission is performed.

  On the other hand, when the propagation state is bad (when the threshold level is below TH), the modulation method is QPSK (Quadrature Phase Shift keying), the coding rate is reduced, and data transmission is performed at low speed.

  In this way, the quality is kept constant by changing the transmission rate of the user by the AMC method. That is, as shown in FIG. 1, in HSDPA, the modulation scheme and coding rate of HS-DSCH, which is user data, are made variable according to the propagation state I. And HS-SCCH which is the control information regarding this user data is also transmitted with user data (HS-DSCH).

  However, at this time, for the HS-SCCH as control information, as shown in FIG. 2 showing the relationship between the radio environment and the information amount, the coding rate of error correction coding with respect to the control information IV is constant. Regardless of whether the environment I is good or bad, the amount of information transmitted is constant.

  In such a case, when the wireless environment I is in a good state, the quality is excessive with respect to the transmitted control information.

  Further, in the next-generation mobile communication system, multi-carrier transmission and multi-input multi-output (MIMO) transmission using a plurality of antennas are used to realize high-speed data transmission. In this case, it is possible to further improve the transmission characteristics by using adaptive control of radio parameters for each subcarrier and each transmission antenna.

  When such MIMO is used, the presence / absence of MIMO application is controlled according to the good / bad propagation state I as shown in FIG. That is, in FIG. 3 showing the relationship between the presence / absence of MIMO application and the transmission rate, the transmission rate is high when MIMO is applied, and the transmission rate is low otherwise.

  Further, the applicant first selects one control channel format from a plurality of control channel formats having different information amounts according to predetermined conditions (with / without MIMO application) in a transmission system using MIMO, An invention of transmitting a control channel using the selected control channel format has been proposed (International Publication WO2006 / 070466: hereinafter simply referred to as a prior application).

  The purpose of this prior application is based on the assumption that the number of information bits in the control channel differs depending on whether or not MIMO is applied. As shown in FIG. 4 (Table 2), when MIMO is applied to user data (period III), the number of information bits IV of the control channel increases. On the other hand, when MIMO is not applied to user data, it is assumed that the number of information bits of the control channel decreases as shown in FIG. 5 (Table 3).

  Therefore, as shown in FIG. 6 showing the relationship between the MIMO application and the information amount of the control channel, the number of variable parameters increases in the period III of the propagation environment I where the MIMO is applied, and the number of information bits required for the control channel is There is a problem of increasing. Furthermore, even when the number of simultaneously multiplexed users increases in one frame, there is a problem that the information on the control channel increases in proportion to the number of users.

3GGP TS 25.212 V5.9.0 (2004-06)

  Therefore, the present invention makes variable the coding rate in error correction coding for HS-SCCH, which is control channel information, in packet-type data transmission to which adaptive coding and modulation (AMC) is applied. We focused on solving the above problem.

  A first aspect of the present invention that solves the above problem is a control channel information transmission method for performing adaptive coding modulation, wherein a transmission side has a constant coding rate for the control channel information. The error correction coding is performed at the control channel information, the error correction coded control channel information is modulated and transmitted by a predetermined modulation method, and the error correction coded signal is input multiple times before the modulation. According to the presence or absence of application of multiple outputs, the code is thinned out or the code is repeated.

  A second aspect of the present invention that solves the above problem is a transmission system that transmits control channel information for performing adaptive coding modulation, and the base station side provides a fixed amount for the control channel information. An error correction coding device that performs error correction coding at a coding rate; a modulation device that modulates control channel information that has been error correction coded by the error correction coding device according to a predetermined modulation method; and the error It has a device for thinning out the code or repeating the code depending on whether multi-input multi-output is applied to the output signal of the correction coding device before modulation by the modulation device. To do.

  In the above aspect, when the multi-input multi-output is applied, the code decimation amount is larger than the decimation amount when the multi-input multi-output is not applied, and the transmission code bit number is set to the multi-input multi-output. A predetermined number is used regardless of whether or not it is applied.

  Further, in the transmission method, at the receiving side, the transmitted control channel information is received, demodulated in accordance with the predetermined modulation method, and the code thinning according to whether the multi-input multi-output is applied or not is performed. Alternatively, error correction decoding corresponding to each coding rate reflecting the repetition of the signal is performed.

  Further, in the above aspect, the error correction decoding apparatus corresponding to each of the code rate reflecting the code thinning or the code repetition according to whether the multi-input multi-output is applied or not is commonly used on the receiving side. Perform error correction decoding on the received signal, further determine the likelihood of the error correction decoded signal, and output an error correction decoded signal that has been validated based on the determination result of the certainty It is characterized by doing.

  The features of the present invention will become more apparent from the embodiments of the present invention described with reference to the following drawings.

FIG. 1 is a diagram illustrating a relationship between a wireless environment and a transmission rate in AMC control of HSDPA and HS-DSCH as conventional techniques. FIG. 2 is a diagram illustrating the relationship between the radio environment and the amount of information in conventional HSDPA and HS-SCCH. FIG. 3 is a diagram illustrating a relationship between a radio environment and a transmission rate in the HS-DSCH to which MIMO is applied in the prior application. FIG. 4 is a diagram illustrating an example of a control channel format with MIMO application. FIG. 5 is a diagram illustrating an example of a control channel format without applying MIMO. FIG. 6 is a diagram illustrating a relationship between a radio environment and an information amount in HS-SCCH to which MIMO is applied. FIG. 7 is a block diagram illustrating a configuration example of a transmission system including the base station 1 and the user terminal 2 to which the present invention is applied. FIG. 8 is a diagram showing a configuration of the control channel generation unit 12 corresponding to the prior invention. FIG. 9 is a diagram illustrating a first configuration example of the control channel generation unit 12 according to the present invention. FIG. 10 is a diagram illustrating the relationship between the MIMO application and the information amount of the control channel when the present invention is applied. FIG. 11 is a diagram showing another configuration example of the control channel generation unit 12 according to the present invention. FIG. 12 is a configuration example of a control channel demodulation unit in a user terminal according to the present invention. FIG. 13 is a diagram showing the effect of the present invention in comparison with the case of using the invention of the prior application.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 7 is a block diagram illustrating a configuration example of a transmission system including the base station 1 and the user terminal 2 to which the present invention is applied. In particular, the present invention is characterized by the configuration of the embodiment of the control channel generator 12.

  The features of the present invention will be described using an embodiment in which the above-mentioned MIMO is applied to downlink control channel transmission from the base station 1 to the user terminal 2. However, the application of the present invention is not limited to the transmission system configuration shown in FIG.

  The format selection / allocation unit 10 of the base station 1 selects a control channel format based on information such as the number of multiplexed users, transmission / reception functions of user terminals, downlink QoS, and downlink CQI (Channel Quality Indicator).

  Here, examples of the control channel format to be selected are as shown in FIG. 4 (Table 2) and FIG. 5 (Table 3).

  The control format A shown in FIG. 4 (Table 2) includes modulation scheme (antenna 1) to modulation scheme (antenna 4), coding rate, spreading factor, and code set as adaptive control parameters. For example, in the modulation scheme (antenna 1) to modulation scheme (antenna 4), four types of modulation schemes (QPSK, 8PSK, 16QAM, 64QAM) are set as variable ranges. In the control channel format A shown in Table 2, the types of adaptive parameters and the variable range are wide. For example, during MIMO transmission, the modulation scheme can be made variable for each antenna.

  On the other hand, the control format B shown in FIG. 5 (Table 3) includes a modulation scheme (common to antennas), a coding rate, a spreading factor, and a code set as adaptive control parameters. For example, as the modulation scheme (common), two types of modulation schemes (QPSK, 16QAM) are set as variable ranges. In the control channel format B shown in Table 3, the types and variable ranges of adaptive control parameters are limited compared to the control channel format A, and the number of bits is about ½ of the control channel format A.

  Returning to FIG. Information indicating the allocation of the control channel format selected by the format selection / allocation unit 10 is notified from the signaling generation unit 11 to the user terminal 2 through the selection unit 15 and the transmission unit 16 as signaling information. The format allocation information is notified to the control channel generation unit 12 and the data channel generation unit 13.

  The control channel generation unit 12 has a different configuration and operation corresponding to an embodiment described later, but includes an error correction coding device and a modulation device as a basic configuration.

  The control channels and data channels generated by the control channel generator 12 and the data channel generator 13 are multiplexed by the multiplexer 14 based on the format allocation information, and then transmitted by the transmitter 16 via the downlink to the user terminal 2. Sent to.

  The signaling demodulator 22 of the user terminal 2 demodulates the signaling information (format allocation information) notified from the base station 1 through the receiver 20, and notifies the control channel demodulator 23 of the downlink control channel format. The control channel demodulator 23 demodulates the control channel based on the downlink control channel format notified from the signaling demodulator 22. The control channel demodulator 23 notifies the data channel demodulator 21 of the downlink adaptive control parameters demodulated from the control channel.

  The data channel demodulator 21 demodulates the data channel using the adaptive control parameter notified from the control channel demodulator 23.

  The downlink CQI used for selecting the downlink control channel format is measured by the propagation path measurement unit 24 of the user terminal 2. The downlink CQI is transmitted to the base station 1 by the uplink control channel from the user terminal 2 to the base station 1 together with the uplink QoS and the transmission / reception function of the user terminal 2.

  Next, uplink control channel transmission from the user terminal 2 to the base station 1 will be described.

  The uplink control channel format is selected by the format selection / allocation unit 10 of the base station 1 in the same manner as the downlink control format. For selection of the uplink control channel format, information such as the number of multiplexed users, transmission / reception functions of user terminals, uplink QoS, uplink CQI (Channel Quality Indication), and the like are used.

  The selected uplink control format is notified from the signaling generator 11 to the user terminal 2 via the selector 15 and the transmitter 16 as signaling information. The signaling demodulator 22 demodulates the signaling information notified from the base station 1, determines the uplink control channel and data channel allocation (multiplexing method), and uses the format allocation information as the control channel generator 25 and the data channel. Notify the generation unit 27.

  The base station 1 notifies the uplink control channel demodulation unit 18 of the uplink control channel format selected by the format selection / allocation unit 10.

  The control channel demodulation unit 18 demodulates the control channel based on the uplink control channel format notified from the format selection / allocation unit 10. The control channel demodulation unit 18 notifies the data channel demodulation unit 19 of the demodulated uplink adaptive control parameters.

  The data channel demodulator 19 uses the adaptive control parameter notified from the control channel demodulator 18 to perform data channel demodulation processing. The uplink CQI used for selecting the uplink control channel format is measured by the propagation path measurement unit 17 of the base station 1.

  The measured uplink CQI is notified from the channel measurement unit 17 to the format selection / allocation unit 10. Further, the uplink QoS and downlink CQI transmitted to the base station 1 and the transmission / reception function of the user terminal 2 are sent to the format selection / allocation unit 10 by the uplink control channel from the user terminal 2 to the base station 1.

  Next, a configuration example of the control channel generation unit 12 will be described with reference to FIG. Here, in the prior application, as shown in FIGS. 4 and 5, it is assumed that MIMO is applied and the number of information bits of the control channel varies depending on whether or not MIMO is applied.

  That is, when MIMO is applied to user data, the number of information bits of the control channel is large (see FIG. 4), and when no MIMO is applied to user data, the number of information bits of the control channel is small (see FIG. 5). One control channel format is selected from the control channel formats.

  In such a case, the configuration of the control channel generator 12 is as shown in FIG.

  An error correction encoding device 120 and a modulation device 121 are included. Error correction coding is performed by the error correction coding device 120, and correspondingly, error correction decoding is performed by the control channel demodulation unit 23 on the user terminal 2 side.

  Here, assuming that the coding rate R, which is the ratio between the number of bits of code information to be transmitted and the number of bits of transmission code obtained by error correction coding, is R = 0.241, MIMO application in FIG. When there is no transmission, the number of bits of the transmission code is 282 = {68 × (1 / 0.241)} bits with respect to the number of bits 68 of the code information of the frame to be transmitted.

  On the other hand, when MIMO is applied and the number of bits of code information of a frame to be transmitted is 141, the number of bits of a transmission code is 585 = {141 × (1 / 0.241)} bits.

  Thus, since the coding rate is fixed, there is a problem that the number of transmission code bits when MIMO is applied increases as shown in FIG.

  Therefore, this problem is solved by the present invention.

  FIG. 9 is a diagram illustrating a first configuration example of the control channel generation unit 12 according to the present invention. Similar to the configuration of FIG. 8, the control channel generation unit 12 includes an error correction encoding device 120 and a modulation device 121.

  A feature different from the configuration of FIG. 8 is that the coding rate in the error correction coding apparatus 120 is variable.

  When the coding rate is large, it is weak against propagation path errors, and when the coding rate is small, it is strong against propagation path errors. On the other hand, MIMO is applied when there are few propagation path errors, and is not applied when there are many errors.

  For this reason, when MIMO is applied to user data, the coding rate of the error correction coding apparatus for generating a control channel is increased. Conversely, without applying MIMO to user data, the coding rate of the error correction coding apparatus for generating the control channel is reduced.

  As an example, when MIMO is applied to user data, the coding rate of the error correction coding apparatus 120 of the control channel generation unit 12 is set to 0.5. As a result, the number of bits of the transmission code is 282 (= 141 ÷ 0.5) bits. On the other hand, when MIMO is not applied to user data, 282 (= 141 ÷ 0.24) bits are transmitted, assuming that the coding rate of the error correction coding apparatus 120 is 0.24, as in the example of FIG. Become.

  Thereby, the transmission code bits are the same regardless of whether MIMO is applied or not, and the quality of control information can be made constant without wasting radio resources.

  FIG. 10 is a diagram illustrating the relationship between the MIMO application and the information amount of the control channel when the present invention is applied. In comparison with FIG. 6, even when MIMO is applied, the number of transmission code bits after error correction coding can be made constant. This prevents resources from being wasted.

  FIG. 11 is a diagram illustrating another example configuration of the control channel generation unit 12. This embodiment is characterized in that a device 122 for selectively applying a puncture function or a repetition function is provided between the error correction coding device 120 and the modulation device 121.

  That is, in this embodiment, the coding rate of the error correction coding apparatus 120 is made constant regardless of whether or not MIMO is applied. On the other hand, the coding rate is equivalently changed by a device 122 having a puncture function or a repetition function placed on the output side of the error correction coding device 120.

  Thus, the fact that the coding rate is variable on the input side of the modulation device 121 has the same meaning as the configuration of the control channel generation unit 12 shown in FIG.

  If the apparatus 122 has a puncture function, the apparatus 122 performs a process of thinning out output data of the error correction coding apparatus 120 at regular intervals by the puncture function when MIMO is applied. When MIMO is not applied, the output data of the error correction coding apparatus 120 is passed as it is. Thereby, the fine and the number when the output of the error correction coding apparatus 120 is input to the modulation apparatus 121 can be made the same regardless of whether MIMO is applied or not.

  When the repetition function is provided, the device 122 repeatedly outputs the same bits of the output data of the error correction coding device 120 by the repetition function when MIMO is not applied. Also in this case, the number of transmission bits when MIMO is not applied can be made substantially the same as the number of transmission bits when MIMO is applied.

  FIG. 12 shows still another embodiment of the present invention. In the transmission system in FIG. 7, the presence / absence of MIMO application and the format notification in the control channel generation unit 12 are performed as functions of the signaling generation unit 11 in the base station 1. The embodiment shown in FIG. 12 does not require the function of the signaling generation unit 11.

  That is, the user terminal 2 on the receiving side receives data using two types of control channel formats, that is, control channel formats corresponding to the cases where MIMO is applied and not applied. Then, any format that seems to be correct is detected from the received data. As a result, the base station 1 on the transmission side can notify the reception side of the presence / absence of MIMO application without using the resource of the information bit for notification of the presence / absence of MIMO application.

  In the control channel demodulator 23 shown in FIG. 12, two errors corresponding to each of the two types of control channel formats on the output side of the demodulator 230 that demodulates a signal transmitted from the base station 1 side without signaling demodulation. Correction decoders 231a and 231b are included.

  The first error correction decoding device 231a can obtain a correct output when error correction decoding is performed on a frame signal of 68 bits when MIMO is not applied. For this purpose, the error correction decoding apparatus 231a performs error correction decoding with a coding rate = 0.24.

  On the other hand, the second error correction decoding device 231b can obtain a correct output when error correction decoding is performed on a frame signal having 141 bits when MIMO is applied. For this purpose, error correction decoding is performed with a coding rate = 0.5.

  The reliability determination and selection device 232 determines which decoding result is likely to be correct from the outputs of the first and second error correction decoding devices 231a and 231b, and based on the result, the error correction decoding devices 231a and 231b. Select the output on one side.

  As a result, it is possible to save information bit resources for reporting whether or not MIMO is applied.

  FIG. 13 is a diagram showing the effect of the present invention in comparison with the case of using the invention of the prior application.

  FIG. 13A shows a transmission power ratio from a base station using HSDPA. The remaining power not shown in FIG. 13A becomes the power allocated to the traffic channel.

  FIG. 13B shows the power available in the traffic channel obtained from FIG. 13A for each number of HS-SCCH channels. As described above, in the invention in the prior application, the HS-SCCH coding rate is constant even when the amount of information increases. For this reason, the power that can be used in the traffic channel differs depending on whether or not MIMO is applied (see FIGS. 13B and III), but in the present invention, this is constant (see FIGS. 13B and IV).

  For example, when there are two traffic channels (arrows in FIG. 13B), the effect of the present invention is 1.5 times as much as the power of the prior invention.

  As described above with reference to the drawings, according to the present invention, by making the coding rate of the error correction code variable according to the mode of the control channel, the transmission quality can be made constant regardless of the quality of the propagation state. In addition, even when MIMO is applied, it is possible to prevent excessive quality with respect to control information bit transmission.

Claims (12)

A control channel information transmission method for performing adaptive coding modulation,
On the sending side,
The control channel information is subjected to error correction coding at a constant coding rate,
The error correction encoded control channel information is modulated and transmitted by a predetermined modulation method,
Further, the code subjected to error correction coding is subjected to code thinning or code repetition according to whether or not multiple input multiple output is applied before the modulation.
A method of transmitting control channel information. In claim 1,
On the receiving side,
When the multi-input multi-output is applied, the code decimation amount is set larger than the decimation amount when the multi-input multi-output is not applied, and the transmission code bit axis is determined regardless of whether the multi-input multi-output is applied or not. Number
A method of transmitting control channel information. In claim 1 or 2,
On the receiving side,
A coding rate that receives the transmitted control channel information, demodulates it according to the predetermined modulation method, and reflects the code thinning or the signal repetition depending on whether the multi-input multi-output is applied Error correction decoding corresponding to each of
A method of transmitting control channel information. In claim 1 or 2,
On the receiving side, for signals received in common by the error correction decoding apparatus corresponding to each of the code rate reflecting the code decimation or repetition of the code depending on whether the multi-input multi-output is applied Perform error correction decoding,
Further, determine the probability of the error correction decoded signal,
Based on the determination result of the certainty, outputs the error-corrected decoded signal that is validated,
A method of transmitting control channel information. A transmission system for transmitting control channel information for performing adaptive coding modulation,
On the base station side,
An error correction coding apparatus that performs error correction coding at a constant coding rate on the control channel information;
A modulation apparatus that modulates control channel information that has been error correction encoded by the error correction encoding apparatus, according to a predetermined modulation scheme;
Furthermore, the apparatus has a device that performs code decimation or repetition of the code depending on whether multi-input multi-output is applied before the modulation by the modulation device with respect to the output signal of the error correction coding device ,
A transmission system characterized by that. In claim 5,
On the receiving side,
The apparatus sets the code thinning amount larger than the thinning amount when the multi-input multi-output is not applied when the multi-input multi-output is applied, and sets the number of transmission code bits to the multi-input multi-output application. A predetermined number regardless of the presence or absence,
A transmission system characterized by that. In claim 5,
On the receiving side,
A coding rate that receives the transmitted control channel information, demodulates in accordance with the predetermined modulation scheme, and reflects the code thinning or the code repetition depending on whether the multi-input multi-output is applied A device that performs error correction decoding at a coding rate corresponding to each of
A transmission system comprising: In claim 5 or 6,
On the receiving side,
Perform error correction decoding on commonly received signals at a coding rate corresponding to each coding rate reflecting the code decimation or repetition of the code depending on whether the multi-input multi-output is applied A plurality of error correction decoding devices;
A device that determines the probability of the error correction decoded signal by the plurality of error correction decoding devices, and outputs an error correction decoded signal that is validated based on the determination result of the probability.
A control channel information transmission system comprising: A base station in a transmission system for transmitting control channel information for performing adaptive coding modulation,
An error correction coding apparatus that performs error correction coding at a constant coding rate on the control channel information;
A modulation apparatus that modulates control channel information that has been error correction encoded by the error correction encoding apparatus, according to a predetermined modulation scheme;
Furthermore, the apparatus has a device that performs code decimation or repetition of the code depending on whether multi-input multi-output is applied before the modulation by the modulation device with respect to the output signal of the error correction coding device ,
A base station characterized by that. In claim 9,
The apparatus sets the code thinning amount larger than the thinning amount when the multi-input multi-output is not applied when the multi-input multi-output is applied, and sets the number of transmission code bits to the multi-input multi-output application. A predetermined number regardless of the presence or absence,
A base station characterized by that. A user terminal that receives control channel information corresponding to the base station of claim 9 or 10,
A coding rate that receives the transmitted control channel information, demodulates in accordance with the predetermined modulation scheme, and reflects the code thinning or the code repetition depending on whether the multi-input multi-output is applied A device that performs error correction decoding at a coding rate corresponding to each of
A user terminal characterized by comprising: A user terminal that receives control channel information corresponding to the base station of claim 9 or 10,
Perform error correction decoding on commonly received signals at a coding rate corresponding to each coding rate reflecting the code decimation or repetition of the code depending on whether the multi-input multi-output is applied A plurality of error correction decoding devices;
A device that determines the probability of the error correction decoded signal by the plurality of error correction decoding devices, and outputs an error correction decoded signal that is validated based on the determination result of the probability.
A user terminal characterized by comprising:

Images