JP5056893B2 - Pilot arrangement method in mobile radio communication system and transmission / reception apparatus to which this method is applied - Google Patents

Description

  The present invention relates to a pilot arrangement method in a mobile radio communication system and a transmission / reception apparatus to which the pilot arrangement method is applied.

  Regarding mobile radio communication systems, further next-generation radio access schemes for third-generation mobile communications have been deliberated under the name of LTE (Long Term Evolution) by 3GPP (3rd Generation Partnership Project).

  In LTE, it is assumed that frequency and time scheduling is performed in units of resource blocks (RB: Resource Block) or resource units (RU: Resource Unit).

  FIG. 1 is a diagram illustrating such frequency and time scheduling. A use band is divided | segmented into a resource block unit, and a frequency is allocated to a some user terminal, ie, a mobile terminal (UE: User Equipment).

  Further, the frequency in resource block units is switched to and assigned to a plurality of mobile terminals (UEs) in a time axis direction in a time division manner in units of one subframe.

  Scheduling of allocation in units of subframes in the frequency axis and time axis directions is performed by the base station.

Here, when scheduling, it is common to schedule based on channel quality information (CQI: Channel Quality Information) for each resource block (RB) or resource unit (RU).

  The CQI corresponds to the signal-to-noise ratio (SIR), and the SIR measurement on the mobile terminal side is generally performed by monitoring the common pilot level common to users from the base station. Done.

  In the LTE described above, it is shown that common pilot channels are arranged at intervals in the frequency direction in the downlink (Non-Patent Document 1).

  That is, FIG. 2 is a diagram illustrating an example in which common pilot channels (PCs) described in Non-Patent Document 1 are arranged at intervals in the frequency direction.

  Further, in Patent Document 1, a common pilot symbol and a known sequence are added for each slot in order to increase the measurement accuracy of SIR, and the communication device on the receiving side uses the common pilot symbol and the known sequence in the reception slot. A configuration for estimating SIR is proposed.

  In the above-described aspect indicated by LTE, when the pilot channel insertion interval is very large, when the number of transmission antennas is large, or when the number of multiplexed users is large, the pilot arrangement interval is large. Thereby, the number of common pilots arranged in a certain resource block and resource unit is reduced.

  Here, measurement of I (interference power) when measuring SIR is generally expressed by Equation 1, and a conceptual diagram of the measurement is shown in FIG. Equation 1 means that the difference between the average value of the pilot levels before and after and the level of the pilot channel position is obtained as interference power.

In the above equation 1, as shown in FIG. 3, P _j is a pilot after pilot pattern cancellation by the j-th subcarrier.

3GPP TR25.814 v7.0.0 (7.1.1.2.2)

JP 2003-348046 A

  Here, when the pilot channel arrangement interval is large, that is, when the pilot frequency interval used for measurement is widened, particularly in an environment with a large delay dispersion, I (interference power) is increased due to frequency selectivity between subcarriers. It will be greatly estimated.

  As a result, the accuracy of SIR estimation in a certain resource block RB or resource unit RU unit deteriorates.

  Therefore, when the pilot channel interval is large, the accuracy of SIR estimation deteriorates, and even if scheduling is performed based on the CQI corresponding to the SIR, the CQI accuracy is bad. May fall.

  In the above-mentioned Patent Document 1, it is described that the estimation accuracy of SIR is increased using a pilot and a known sequence, but the interval between pilot channels is not mentioned.

  Therefore, an object of the present invention is to provide a pilot arrangement method in a mobile radio communication system and a transmission / reception apparatus to which the method is applied, which solves the inconvenience when the interval between pilot channels is large.

  A feature of the present invention that achieves the above-described object is a pilot arrangement method in a mobile communication system that divides a use frequency band into a plurality of predetermined bands and performs time division multiplexing, and includes the plurality of predetermined frequency bands. A known pilot symbol is inserted at a predetermined reference interval, and the known pilot symbol is inserted and arranged at an interval smaller than the predetermined reference interval in at least one frequency band of the plurality of predetermined frequency bands; The frequency band in which symbols are inserted and arranged at intervals smaller than the predetermined reference interval is changed in accordance with a predetermined pattern.

  Further, the known pilot symbols are inserted and arranged in an interval smaller than the predetermined reference interval in at least one frequency band of the plurality of predetermined frequency bands based on measurement information of the signal-to-noise ratio on the receiving side. .

This feature increases the chances of SIR measurement by known pilots and improves the accuracy of estimating I (interference power) because the frequency interval is small, so that the transmission side performs scheduling based on CQI corresponding to SIR. Since the CQI accuracy is poor, the problem that the scheduling is adversely affected and the throughput is reduced can be avoided.

It is a figure explaining a frequency and time scheduling. The example arrange | positioned at intervals in the frequency direction of the common pilot channel demonstrated in the nonpatent literature 1 is shown. It is a figure which shows the conceptual diagram of the measurement of I (interference power) when measuring SIR generally represented by Formula 1. It is a 1st example of arrangement | positioning of the pilot channel according to this invention. It is a figure which shows the structure of the transmission apparatus of the base station which is a transmission side apparatus corresponding to the Example of FIG. It is a figure which shows the structural example of the transmission / reception apparatus by the side of the mobile terminal corresponding to the transmission apparatus of FIG. It is a figure which shows the pilot channel arrangement | positioning of a 2nd Example. It is a figure which shows the transmission apparatus structure of the transmission side corresponding to the Example of FIG. It is a figure which shows the transmission / reception apparatus structure by the side of the reception of the pilot channel corresponding to FIG. 7, ie, a mobile terminal side. It is a figure which shows the structure of the transmission apparatus of the transmission side of 3rd Example of this invention. It is a figure which shows the structure of the transmission / reception apparatus of the receiving side corresponding to the transmission apparatus of the transmission side of FIG. It is a figure which shows the structure of the transmission apparatus of the transmission side of 4th Example of this invention. It is a figure which shows the structure of the transmission / reception apparatus of the receiving side corresponding to the transmission apparatus of the transmission side of FIG. It is a figure which shows the pilot channel arrangement | positioning of the 5th Example according to this invention. It is a figure which shows the structural example which restrict | limits the number which inserts a shared pilot channel densely with the information amount (communication rate) transmitted, such as a control channel, in the transmission apparatus of a transmission side. It is a figure which shows the example in which the number which inserts a shared pilot channel densely is restrict | limited by the information amount (communication rate) transmitted, such as a control channel, in the transmission apparatus of a transmission side. It is a figure which shows the example which controls arrangement | positioning of a shared pilot channel according to the state of delay dispersion | distribution. It is a graph which shows the effect by this invention.

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

  FIG. 4 is a first arrangement example of pilot channels according to the present invention.

  Normally, pilot channels (PC) are arranged at a predetermined reference interval as a standard according to the standard, for example, 6 subcarriers (SC) (six frequency bands obtained by dividing a used frequency band into a plurality of predetermined bands). In this case, as shown in FIG. 4, according to the present invention, pilot channels are arranged densely (for example, continuously) at intervals smaller than a normal arrangement interval in a predetermined frequency region.

  That is, in the first embodiment shown in FIG. 4, a pilot channel is continuously arranged in the first resource block RB of each subframe.

  FIG. 5 shows a configuration example of a transmission apparatus of a base station which is a transmission side communication apparatus corresponding to the embodiment of FIG. 4, and FIG. 6 shows a configuration example of a transmission / reception apparatus of a mobile terminal which is a corresponding reception side communication apparatus. Yes.

  On the transmission side shown in FIG. 5, the pilot signal from the pilot channel generator 2 and the data and control signal from the data and control signal generator 4 are channel-multiplexed by the multiplexing circuit 3 and modulated and amplified by the transmitter 5. It is transmitted from the transmission antenna 6.

  Here, in the transmission apparatus shown in FIG. 5, the pilot channel generator 2 acquires position information for arranging the pilot channel from the pilot channel arrangement information generating unit 1, and outputs a common pilot signal at the timing of the corresponding position. And output to the multiplexing circuit 3.

  FIG. 6 is a block diagram showing a configuration of a transmission / reception apparatus on the pilot reception side, that is, the mobile terminal side, corresponding to FIG.

  The antenna 10 receives a pilot signal and a signal in which data and a control signal are multiplexed. The reception signal is demodulated by the reception unit 11, branched by the separation circuit 12, and input to the data / control signal demodulation / decoding circuit 13 and the pilot channel extraction unit 14.

  The pilot channel extraction unit 14 controls the pilot detection timing in the pilot channel extraction unit 14 based on the common pilot channel arrangement information 15 that is previously notified or known from the transmission side.

  The notification from the transmission side to the common pilot channel arrangement information 15 is known in advance, can be notified by a control signal before the scheduling change, or can be notified by any other method.

  The pilot channel extraction unit 14 detects a common pilot symbol at a controlled pilot detection timing and outputs the level to the SIR measurement unit 16.

  The pilot channel extraction unit 14 further gives detection pilot timing to the data / control signal demodulation / decoding circuit 13, and provides a reference of data / control signal reception timing in the control signal demodulation / decoding circuit 13.

  The SIR measurement unit 16 measures the SIR that is a signal-to-noise ratio from the level of each received pilot symbol notified from the pilot channel extraction unit 14.

  The measured SIR is sent to the CQI information generation unit 20. Further, other information 21 related to the line state is also sent to the CQI information generation unit 20 as necessary.

  The CQI information generation unit 20 creates CQI information corresponding to the SIR value by an existing processing method based on the measured SIR sent from the SIR measurement unit 16 and other information 21 related to the line state.

  The multiplexing circuit 23 multiplexes the CQI information thus created, the data / control signal from the data / control signal generation unit 22, and sends the multiplexed data to the transmission unit 24.

  The transmission unit 24 modulates and amplifies the multiplexed signal and transmits it from the antenna 25 to the base station side.

  On the base station side, the SIR is estimated based on the CQI information sent from the transmitting / receiving device on the mobile terminal side. Then, based on the estimated SIR, the pilot channel arrangement information generating unit 1 generates position information for arranging the pilot channel by an existing method.

  In this way, the newly generated common pilot channel arrangement information is set based on the reception state on the receiving side, so that the SIR estimation accuracy obtained based on the common pilot can be improved.

  FIG. 7 is a diagram illustrating a pilot channel arrangement according to the second embodiment. In the first embodiment of FIG. 4, the position where the pilots are continuously arranged is the head position of each subframe. On the other hand, the example shown in FIG. 7 has a configuration in which the positions where pilots are continuously arranged at predetermined time intervals are changed.

  For this purpose, the transmission apparatus on the transmission side shown in FIG. 8 corresponding to the embodiment of FIG. Yes. Therefore, the pilot arrangement information generating unit 1 controls the pilot generation timing of the pilot channel generator 2 by changing the pilot channel arrangement at the set time period.

  The other configuration functions of the transmission apparatus on the transmission side are the same as those of the configuration of FIG. 5 described above.

  On the other hand, FIG. 9 shows a transmission / reception apparatus configuration on the pilot reception side, that is, the mobile terminal side, corresponding to FIG.

  The receiving side transmission / reception apparatus shown in FIG. This time period is also known or notified in advance from the transmission side, as in the previous embodiment. Therefore, the pilot channel arrangement information generation unit 15 can create pilot channel arrangement information on the reception side in synchronization with the transmission side.

  The pilot channel extraction timing in the pilot channel extraction unit 14 is controlled by the pilot channel position created by the pilot channel arrangement information generation unit 15. Other configurations and operations are the same as those described with reference to FIG.

  FIG. 10 shows the configuration of the transmission device on the transmission side according to the third embodiment of the present invention, and FIG. 11 shows the configuration of the transmission / reception device on the reception side corresponding thereto.

  In the transmission apparatus on the transmission side in FIG. 10, a fixed pattern generation unit 70 is provided on the transmission side, and a fixed timing is sent to the pilot channel arrangement information generation unit 1 to control the pilot channel arrangement position.

  As shown in FIG. 11, the receiving side provides a corresponding fixed pattern generation unit 27 to control the pilot channel arrangement information generation unit 15.

  At least the fixed pattern is set so that the pilots are arranged more densely with respect to the reference pilot channel arrangement position determined by the standard.

  FIG. 12 shows the configuration of the transmission device on the transmission side according to the fourth embodiment of the present invention, and FIG. 13 shows the configuration of the transmission / reception device on the reception side corresponding thereto.

  In the fourth embodiment, the pilot arrangement position information generated by the pilot channel arrangement information generating unit 1 is embedded in the control signal channel and sent to the receiving side.

  Therefore, as shown in FIG. 13, in the receiving side apparatus, the pilot channel arrangement information generating unit 15 extracts pilot channel arrangement information inserted in the control channel demodulated / decoded by the data / control signal demodulation / decoding circuit 13. To do.

  Then, the extraction timing in the pilot channel extraction unit 14 is generated from the extracted pilot channel arrangement information as in the previous embodiment.

  In the fourth embodiment, it is not necessary to notify the receiver side of pilot arrangement information in advance.

  FIG. 14 is a diagram showing a pilot channel arrangement as a fifth embodiment according to the present invention.

  In this embodiment, a continuous pilot channel arrangement is adaptively provided at a plurality of locations.

  And the example of a structure shown in FIG.15, FIG16 and FIG.17 is possible as a reference | standard which provides the pilot channel arrangement | sequence continuous to several places adaptively.

  That is, FIG. 15 is a configuration example in which the number of densely inserted pilots is limited by the amount of information to be transmitted (communication rate) such as a data channel in the transmission apparatus on the transmission side.

  Therefore, when priority is given to transmission of the data channel, the state of the data signal transmitted by the data and control signal generator 4 is notified to the pilot channel arrangement information generation unit 1. As a result, the pilot channel arrangement information generating unit 1 determines the communication rate and generates arrangement information that allows dense (continuous) insertion of pilot signals. The pilot channel generation unit 2 sends a pilot to the multiplexing circuit 3 at the pilot insertion timing based on the pilot arrangement information.

  The subsequent processing in FIG. 15 is the same as in the previous embodiment.

  FIG. 16 is a diagram illustrating an example in which the number of densely inserted pilots is limited by the amount of information to be transmitted (communication rate) such as a data channel in the transmission device on the transmission side.

  This is an example of controlling pilot arrangement according to the state of throughput. That is, in the transmission side device, the cell and sector throughput are monitored by a device (not shown). In this monitoring, when the corresponding throughput deteriorates and becomes smaller than the threshold value, the pilot channel arrangement information generating unit 1 is controlled to make the pilot arrangement dense. The pilot channel arrangement information generation unit 1 inserts the dense pilot channel arrangement information into the control channel as in the embodiment shown in FIG. As a result, it is possible to adaptively change the continuous pilot channel arrangement.

  FIG. 17 is an example in which pilot signal arrangement is controlled according to the state of delay dispersion. That is, in the transmission side apparatus, the delay dispersion is monitored by an apparatus (not shown). In this monitoring, when the delay dispersion becomes larger than the threshold value, the estimation accuracy of the pilot arrangement position deteriorates, thereby controlling the pilot channel arrangement information generating unit 1 so that the pilot arrangement is dense. Further, the pilot channel arrangement information generating unit 1 inserts the dense pilot channel arrangement information into the control channel as in the embodiment shown in FIG.

  FIG. 18 is a graph showing the effect of the present invention. According to the present invention, pilot channels are continuously inserted so as to be dense with respect to the reference insertion position (standard position determined by the standard). As a result, as shown in FIG. 18, it can be understood that even when the SIR deterioration is large, the estimated SIR deterioration is small as the pilot insertion interval is small (that is, the pilot insertion is denser).

In FIG. 18, I is when the insertion interval is 1, II is when the insertion interval is 3, III
Is when the insertion interval is set to 6, and the deterioration of the estimated SIR increases as the insertion interval increases. That is, according to the present invention, the decrease in the accuracy of the interference power can be suppressed as the pilot signal insertion interval is smaller.

Claims (8)

A pilot allocation method in a mobile communication system that divides a use frequency band into a plurality of predetermined bands and performs time division multiplexing,
Inserting known pilot symbols into the plurality of predetermined frequency bands at predetermined reference intervals;
Inserting and arranging the known pilot symbols at intervals smaller than the predetermined reference interval in at least one frequency band of the plurality of predetermined frequency bands;
A frequency band in which the known pilot symbols are inserted and arranged at intervals smaller than the predetermined reference interval is changed in accordance with a predetermined pattern;
A pilot arrangement method in a mobile communication system. In claim 1,
Based on the signal-to-noise ratio measurement information on the receiving side, the known pilot symbols are inserted and arranged in at least one frequency band of the plurality of predetermined frequency bands at an interval smaller than the predetermined reference interval.
A pilot arrangement method in a mobile communication system. In claim 1 or 2,
A pilot allocation method in a mobile communication system, wherein a frequency band in which the known pilot symbols are inserted and arranged at intervals smaller than the predetermined reference interval is notified to a reception side through a control channel. In any one of Claims 1 thru | or 3,
A pilot arrangement method in a mobile communication system, wherein the number of frequency bands into which the known pilot symbols are inserted and arranged at an interval smaller than the predetermined reference interval is determined based on a communication rate, cell throughput, or delay dispersion. A base station apparatus in a mobile communication system that divides a use frequency band into a plurality of predetermined bands and performs time division multiplexing,
A generator for generating pilot arrangement information for inserting and arranging known pilot symbols in the plurality of predetermined frequency bands;
A pilot channel generator that outputs a known pilot symbol at a timing based on pilot arrangement information output from the pilot arrangement information generator;
A data and control channel generator for generating data and control channels;
A multiplexing circuit that multiplexes the known pilot output from the pilot channel generation unit and the data and control channel output from the data and control channel generation unit;
A transmitter for frequency and time multiplexing the output of the multiplexing circuit to generate a transmission output;
The generating unit that generates the pilot arrangement information inserts known pilot symbols into the plurality of predetermined frequency bands at a predetermined reference interval, and further adds the predetermined pilot band to at least one frequency band of the plurality of predetermined frequency bands. Generating arrangement information for inserting and arranging the known pilot symbols at intervals smaller than the reference interval, and setting a frequency band for inserting and arranging the known pilot symbols at intervals smaller than the predetermined reference interval to a predetermined pattern Change correspondingly,
A base station apparatus in a mobile communication system. In claim 5,
The generating unit that generates the pilot arrangement information is based on the measurement information of the signal-to-noise ratio in the mobile terminal on the receiving side, and at least one frequency band of the plurality of predetermined frequency bands at an interval smaller than the predetermined reference interval. Generating arrangement information for inserting and arranging the known pilot symbols;
A base station apparatus. A mobile communication system that divides a use frequency band into a plurality of predetermined bands and performs time division multiplexing,
A known pilot symbol is inserted into the plurality of predetermined frequency bands at a predetermined reference interval, and the known pilot symbol is inserted into at least one frequency band of the plurality of predetermined frequency bands at an interval smaller than the predetermined reference interval. Having a base station to insert,
A pattern in which the known pilot symbols are inserted and arranged in the frequency band at an interval smaller than the predetermined reference interval is changed corresponding to a predetermined pattern,
A mobile terminal that receives a signal sent from the base station and extracts a pilot signal of the base from the received signal according to pilot channel arrangement information;
A mobile communication system. A mobile terminal that communicates with a base station in a mobile communication system that divides a use frequency band into a plurality of predetermined bands and performs time division multiplexing,
Means for receiving a signal sent from the base station;
An interval that is inserted from the received signal into the plurality of predetermined frequency bands at a predetermined reference interval at the base station and is smaller than the predetermined reference interval in at least one frequency band of the plurality of predetermined frequency bands Means for extracting and detecting the known pilot symbols inserted and arranged at
A pattern in which the known pilot symbols are inserted and arranged in the frequency band at an interval smaller than the predetermined reference interval is changed corresponding to a predetermined pattern.
A mobile terminal characterized by that.

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