JP2010098525A - Base station apparatus and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station apparatus capable of determining suitable channel assignment to each terminal station device. <P>SOLUTION: The base station apparatus 200 includes a scheduler for determining a channel to be assigned to communication with each terminal station device among a plurality of channels, based on frequencies and receiving quality information on each channel. The scheduler determines assignment preference of each channel for each terminal station device, based on frequencies of each channel. Then, based on the receiving quality information and the assignment preference for each terminal station device, the scheduler determines a channel to be assigned to communication with each terminal station device among the plurality of channels. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base station apparatus and a communication system that determine channel assignment to each terminal station apparatus based on reception quality of each channel measured by the terminal station apparatus.

  As a method to improve communication efficiency (total throughput of the system and effective transmission speed considering the occurrence of reception errors), received signal power and SINR (Signal to Interference plus Noise power Ratio) Based on indicators indicating propagation path conditions such as power ratio) and reception quality, adaptively adjust communication parameters such as modulation method, channel coding rate, error correction coding method, spreading factor, code multiplexing number, transmission power, etc. Has been proposed (see Non-Patent Document 1 below). In particular, a method for adaptively selecting modulation parameters such as a modulation method and a channel coding rate is called an adaptive modulation method.

Further, in a communication system that includes a base station device and a plurality of terminal station devices and uses multicarrier communication in communication (downlink) from the base station device to the terminal station device,
Scheduling for assigning a channel to each terminal station apparatus is performed according to the reception quality of each channel in each terminal station apparatus for downlink signals.

  Furthermore, a method of performing adaptive modulation for each channel including one subcarrier or several subcarriers for the downlink has been studied (see Non-Patent Document 1 and Non-Patent Document 2 below).

  Note that in a communication system that employs scheduling based on the reception quality of the terminal station apparatus or an adaptive modulation scheme, in order to determine allocation and modulation parameters, channel conditions such as received signal power and SINR used for communication, It is necessary to notify the communication partner of an index indicating the reception quality.

  In the next generation communication method, it is considered to perform communication using a wide frequency band in order to realize higher speed communication. However, since it is necessary to avoid the frequency band used by other existing systems, it is difficult to assign a continuous wide frequency band. For this reason, a frequency aggregation technique that collects discontinuously arranged frequency bands and uses them in one system has been proposed (see Non-Patent Document 3 below).

Kishiyama et al. "Experimental results of throughput characteristics of adaptive modulation / demodulation and channel coding in downlink VSF-OFCDM broadband wireless access", IEICE Technical Report, May 2003, RCS 2003-25 Maehara et al. “Study of OFDM / TDD transmission system using subcarrier adaptive modulation”, 2001 IEICE General Conference, March 2001, B-5-100, p. 498 "LTE-Advanced-LTE evolution towers IMT-Advanced", 3GPP, Worksshop, IMT-Advanced, REV-080030, April 2008

  However, when a plurality of frequency bands are collected and used, the propagation speed of the propagation path in each frequency band is different. For this reason, when determining a channel to be assigned to each terminal station apparatus from channels arranged in these multiple frequency bands, it is not appropriate to assign channels using the same reference for each frequency band. .

  The present invention is more appropriate when the base station apparatus determines channel assignment to each terminal station apparatus from channels arranged in a plurality of frequency bands based on reception quality information reported from each terminal station apparatus. An object of the present invention is to provide a base station apparatus and a communication system that can determine an appropriate channel assignment.

According to an aspect of the present invention, a base station apparatus that performs communication by allocating channels to a plurality of terminal station apparatuses from a plurality of channels arranged at a plurality of frequencies, Each terminal from among the plurality of channels based on a radio reception unit that receives reception quality information representing a part or all of the reception quality from each terminal station device, and a frequency of each channel and the reception quality information There is provided a base station apparatus comprising: a scheduling unit that determines a channel to be allocated for communication to the station apparatus.

  The scheduling unit determines an allocation priority of each channel of each terminal station device based on the frequency of each channel, and the plurality of the scheduling units based on the reception quality information and the allocation priority of each terminal station device It is preferable to determine a channel to be allocated to communication to each terminal station device from among the channels. Here, based on the reception quality measurement result of each channel and the selection priority, a channel with good reception quality and high priority is selected.

  It is preferable that the scheduling unit groups a plurality of channels whose frequencies are close to each other and determines the allocation priority for each group.

Further, the scheduling unit sets the allocation priority of a channel or a group of channels arranged at a lower frequency higher than the allocation priority of a channel or a group of channels arranged at a higher frequency. Is preferred.
Furthermore, a moving speed measuring unit that measures a moving speed of each terminal station device is provided, and the scheduling unit further determines an allocation priority of each channel of each terminal station device based on the moving speed measurement result Is preferred.

  The scheduling unit preferably equalizes the allocation priority for all channels when the moving speed measurement result is equal to or less than a first threshold value or equal to or greater than a second threshold value that is greater than the first threshold value.

  It is preferable that the scheduling unit further sets the allocation priority of a channel previously allocated to each terminal station apparatus or a group to which the allocated channel belongs to be high. The previously assigned channel means a value assigned up to now (present), and represents a scheduling result immediately before the previous frame or the like.

  The scheduling unit calculates a weighting factor of each channel based on the allocation priority, multiplies the reception quality represented by the reception quality information of each channel, and selects the channel quality from the plurality of channels based on the multiplication result. It is preferable to determine a channel to be allocated to each terminal station apparatus.

  In addition, a base station apparatus that performs communication using a plurality of transmission antennas by allocating a channel from a plurality of channels arranged at a plurality of frequencies to a plurality of terminal station apparatuses, A radio reception unit that receives reception quality information representing a part or all of the reception quality from each terminal station device, a type of transmission mode using the plurality of transmission antennas, a frequency of each channel, and the reception quality information And a scheduling unit that determines a channel to be allocated to communication to each of the terminal station apparatuses from among the plurality of channels based on the plurality of channels.

  The scheduling unit preferably increases the number of channels allocated to the terminal station device from among the low frequency channels for the terminal station device having the transmission mode of transmission diversity.

  The scheduling unit preferably increases the number of channels allocated to the terminal station apparatus from among the high frequency channels for the terminal station apparatus whose transmission mode is MIMO.

  Further, the communication system performs communication from a base station apparatus to a terminal station apparatus using a plurality of channels arranged at a plurality of frequencies, wherein the base station apparatus receives signals on a part or all of the plurality of channels. A radio reception unit that receives reception quality information representing quality from each terminal station apparatus, and determines a channel to be allocated to each terminal station apparatus from among the plurality of channels based on the frequency of each channel and the reception quality information A scheduling unit, wherein the terminal station apparatus generates a reception quality measurement unit that measures the reception quality of the plurality of channels, and reception quality information that represents the reception quality measurement results of some or all of the plurality of channels. A communication system comprising: a reception quality information generation unit that performs transmission; and a radio transmission unit that transmits the reception quality information to the base station device. It is subjected.

  According to another aspect of the present invention, there is provided a communication method for performing communication from a base station apparatus to a terminal station apparatus using a plurality of channels arranged at a plurality of frequencies, wherein the base station apparatus Receiving reception quality information representing reception quality in part or all of the channel from each terminal station apparatus, and each terminal station apparatus from among the plurality of channels based on the frequency of each channel and the reception quality information Determining a channel to be assigned to the terminal station apparatus, the terminal station apparatus measuring a reception quality of the plurality of channels, and a reception quality representing the reception quality measurement result in a part or all of the plurality of channels There is provided a communication method comprising the steps of generating information and transmitting the reception quality information to the base station apparatus.

  The present invention may be a program for causing a computer to execute the method described above, or a computer-readable recording medium for recording the program. This program may be acquired by a transmission medium such as the Internet.

  According to the present invention, based on the reception quality information reported from each terminal station apparatus, when the base station apparatus determines channel assignment to each terminal station apparatus from channels arranged in a plurality of frequency bands, It is possible to provide a base station apparatus and a communication system that make it possible to determine a more appropriate channel assignment.

  Hereinafter, orthogonal frequency division multiple access (Orthogonal Frequency Division Multiplexing), which is a multiple access method using orthogonal frequency division multiplexing (hereinafter referred to as OFDM), is used for downlink communication from a base station apparatus to a terminal station apparatus. In a cellular system that employs a multiple access (hereinafter referred to as OFDMA) system and performs adaptive scheduling (channel allocation for each terminal station apparatus) for each channel composed of at least one subcarrier, a frequency band composed of a plurality of channels A system to which a frequency aggregation scheme that performs communication by collecting a plurality of communication will be described with reference to an example in which the present invention is applied.

  In the following description of each embodiment, it is assumed that an index calculated based on a pilot symbol, for example, SINR (Signal to Interference plus Noise power Ratio) is used as reception quality information. explain.

[First Embodiment]
FIG. 1 is a diagram showing an example of frequency allocation of downlink channels in the communication technique according to the first embodiment of the present invention. In FIG. 1, a downlink channel uses a plurality of frequency bands transmitted by a plurality of carrier waves with different frequencies for downlink communication, and each frequency band is composed of a plurality of channels.

  FIG. 1 is a diagram illustrating an example in which 16 channels from channel 1 to channel 16 are arranged in order from the lowest frequency.

In FIG. 1A, the frequency bands B1, B2, and B3 are defined for each carrier wave (carrier frequencies fc ₁ , fc ₂ , fc ₃ : fc ₁ <fc ₂ <fc ₃ ) for transmitting each channel. For example, the frequency band B1 includes channels 1 to 4, the frequency band B2 includes channels 5 to 8, and the frequency band B3 includes channels 9 to 16.

  Further, FIG. 1B shows an example in which each frequency band is defined to have the same bandwidth (number of channels). The frequency band b1 includes channel 1 to channel 4, frequency band b2 Includes channel 5 to channel 8, frequency band b3 includes channel 9 to channel 12, and frequency band b4 includes channel 13 to channel 16.

  Note that the definition of the frequency band is not limited to the above example, and may be arranged so that the carrier wave transmitting the channel and the number of included channels are different as long as the frequency band is defined so as to include channels close to each other in frequency.

  FIG. 2 is a schematic block diagram showing a configuration of base station apparatus 200 in the present embodiment. FIG. 3 is a functional block diagram illustrating a schematic configuration example of the terminal station apparatus 300 in the present embodiment.

  As shown in FIG. 2, the base station apparatus 200 includes a first encoding unit 201 that receives control information, a second encoding unit 202 that receives downlink data, a first modulation unit 203, and a second modulation unit. 204, pilot generation unit 205, mapping unit 206, frequency time conversion unit 207, GI (Guard Interval) insertion unit 208, radio transmission unit 209, antenna unit 210, radio reception unit 211, demodulation unit 212, decoding unit 213, a reception quality information storage unit 214, a scheduling unit 215, a pilot separation unit 216, a movement speed measurement unit 217, and a movement speed storage unit 218.

  As illustrated in FIG. 3, the terminal station device 300 includes an antenna unit 301, a radio reception unit 302, a GI removal unit 303, a time frequency conversion unit 304, a demapping unit 305, a first demodulation unit 306, and a second demodulation unit. 307, reception quality measurement unit 308, first decoding unit 309, second decoding unit 310, channel selection unit 311, reception quality information generation unit 312, encoding unit 313, modulation unit 314, wireless transmission unit 315, A pilot insertion portion 316 is provided.

  Next, a downlink transmission operation in base station apparatus 200 will be described with reference to FIG. The first encoding unit 201 performs error correction encoding on the control information to be notified to the terminal station apparatus 300 and the scheduling information which is the downlink scheduling result by the scheduling unit 215 at a predetermined encoding rate, thereby encoding control information. Is generated and output. The first modulation unit 203 modulates the encoding control information generated by the first encoding unit 201 using a predetermined modulation scheme, generates a modulation symbol of the control information, and outputs it.

  The second encoding unit 202 performs error correction encoding on downlink data transmitted on the downlink based on scheduling information, and outputs encoded data. The second modulation section 204 modulates the encoded data generated by the second encoding section 202 based on the scheduling information, and outputs downlink data modulation symbols.

  Pilot generation section 205 generates and outputs a parrot symbol to be inserted into a transmission signal for reception quality measurement at the terminal station apparatus.

  The mapping unit 206 assigns the modulation symbols of the control information generated by the first modulation unit 203 and the pilot symbols generated by the pilot generation unit 205 to predetermined mapping positions (each subcarrier and OFDM symbol of each channel) ( Mapping), the modulation symbol of the downlink data generated by the second modulation section 204 is allocated to each subcarrier of each channel based on the scheduling information, and a transmission symbol is output.

  The frequency time conversion unit 207 performs frequency time conversion, for example, Inverse Fast Fourier Transform (IFFT), on the transmission symbol output from the mapping unit 206, and converts it into an OFDM time signal and outputs it.

  The GI insertion unit 208 adds a guard period GI to the OFDM time signal generated by the frequency time conversion unit 207.

  The radio transmission unit 209 converts the OFDM time signal to which the guard period is added into an analog signal, up-converts the signal to a radio frequency, and transmits the radio signal to the terminal station apparatus 300 from the antenna unit 210.

  In the present embodiment, an example in which the first modulation unit 203 to the wireless transmission unit 209 (the portion surrounded by the one-dot chain line in FIG. 2) are provided corresponding to each frequency band or each carrier wave. Although shown, it may be configured to perform batch processing.

  Next, a downlink reception operation and an uplink reception quality information transmission (notification) operation in terminal station apparatus 300 will be described with reference to FIG.

  A signal transmitted from the base station apparatus 200 is received by the radio reception unit 302 via the antenna unit 301, down-converted from the radio frequency, further converted into a digital signal, and an OFDM time signal is output.

  The GI removal unit 303 removes the guard period GI from the OFDM time signal, and outputs an OFDM time signal from which the guard period GI is removed.

  The time-frequency conversion unit 304 outputs a modulation symbol by performing time-frequency conversion, for example, fast Fourier transform (FFT), on the OFDM time signal output from the GI removal unit 303.

  Demapping section 305 separates and outputs downlink control information modulation symbols and pilot symbols from a predetermined mapping position, and downlink data modulation symbols from others.

  The first demodulator 306 demodulates the modulation symbol of the control information output from the demapping unit 305 based on a predetermined modulation scheme, and outputs coding control information.

  The first decoding unit 309 performs error correction decoding on the coding control information demodulated by the first demodulation unit 306 based on a predetermined coding rate, and provides downlink control information and scheduling information. Is output.

  The second demodulating unit 307 demodulates the modulation symbol of the downlink data output from the demapping unit 305 based on the downlink scheduling information output from the first decoding unit 309, and encodes the encoded data. Output.

  The second decoding unit 310 performs error correction decoding on the encoded data demodulated by the second demodulation unit 307 based on downlink scheduling information output from the first decoding unit 309. , Downlink data is output.

  Reception quality measuring section 308 measures and outputs the reception quality (SINR) of each channel based on the pilot symbols output from demapping section 305.

  The channel selection unit 311 selects a channel for notifying the base station apparatus 200 of the reception quality from a channel with a good reception quality measurement result (hereinafter simply referred to as reception quality) output from the reception quality measurement unit 308. A predetermined number is selected, and selected channel information indicating the selected channel and reception quality of the selected channel are output.

  Reception quality information generating section 312 generates and outputs reception quality information for notifying base station apparatus 200 of the selected channel information and reception quality output by channel selection section 311.

  The encoding unit 313 performs error correction encoding on the reception quality information output from the reception quality information generation unit 312 based on a predetermined encoding rate, and outputs encoded reception quality information.

  Modulation section 314 modulates the encoded reception quality information generated by encoding section 313 based on a predetermined modulation scheme, and outputs reception quality information symbols.

  Pilot insertion section 316 multiplexes pilot symbols with reception quality information symbols and outputs the multiplexed symbols.

  Radio transmission section 315 converts the reception quality information symbol obtained by multiplexing pilot symbols by pilot insertion section 316 into an analog signal, up-converts the signal to a radio frequency, and transmits the radio frequency from antenna section 301 to base station apparatus 200.

  In the present embodiment, an example in which radio receiving section 302 to reception quality measuring section 308 (portions surrounded by a one-dot chain line in FIG. 3) are provided corresponding to each frequency band or each carrier wave. Although shown, it may be configured to perform batch processing.

  Further, in the present embodiment, a case has been described by way of example in which reception quality information is independently notified to base station apparatus 200, but a configuration in which it is multiplexed with uplink data or transmitted as part of uplink data It is also good. At this time, error correction coding and modulation of reception quality information may be performed based on the coding rate and modulation scheme of uplink data.

  Further, in the present embodiment, an example has been described in which each terminal station apparatus selects a predetermined number of channels with good reception quality and notifies base station apparatus 200 of reception quality information for only some channels. . The present invention is not limited to this case, the number of selections may be variable, the reception quality information related to a predetermined number of channels selected according to different criteria may be notified, and each terminal station apparatus may transmit all channels. May be notified, or may be notified of reception quality information regarding some predetermined channels.

  The reception operation of the reception quality information on the uplink in the base station apparatus 200 will be described with reference to FIG.

  A signal transmitted from the terminal station device 300 is received by the radio reception unit 211 via the antenna unit 210, down-converted from a radio frequency, further converted into a digital signal, and a reception quality information symbol in which pilot symbols are multiplexed is converted. Output.

  Pilot separation section 216 separates the multiplexed pilot symbols and reception quality information symbols and outputs them.

  Demodulation section 212 demodulates the reception quality information symbol based on a predetermined modulation scheme and outputs encoded reception quality information.

Decoding section 213 performs error correction decoding on the encoded reception quality information output from demodulation section 212 based on a predetermined coding rate, and outputs the reception quality information.
The reception quality information storage unit 214 stores the reception quality information output from the decoding unit 213.

Based on the pilot symbols separated by pilot separation section 216, movement speed measurement section 217 measures the movement speed of each terminal station apparatus and outputs the movement speed measurement result. The moving velocity v estimates the Doppler frequency f _d from the time variation of the pilot symbol, the method of calculating the Doppler frequency and the carrier frequency f _c estimated _{(v = c · f d /} f c, c is the speed of light ) And the like.

  The moving speed storage unit 218 stores the moving speed measurement result output by the moving speed measuring unit for each terminal station device.

  Based on the reception quality information of each terminal station device stored in the reception quality information storage unit 214 and the moving speed measurement result of each terminal station device stored in the moving speed storage unit 218, the scheduling unit 215 Assignment of downlink data addressed to the station apparatus to the channel, modulation scheme, coding rate, etc. are determined and output as scheduling information. The detailed operation of the scheduling unit 215 will be described later.

  In this embodiment, the case where the base station apparatus measures the moving speed of the terminal station apparatus has been described. However, the moving speed is measured by the same method from the pilot symbol of the downlink received signal in the terminal station apparatus. However, the result may be notified to the base station apparatus.

  Also, in the present embodiment, the error correction coding rate of the downlink control information and scheduling information, the modulation scheme, and the mapping position, the mapping position of the pilot symbol, and the error correction of the uplink reception quality information An example has been described in which the coding rate and the modulation method of coding are determined in advance. However, these pieces of information may be specified based on signals or information separately notified from the base station apparatus to the terminal station apparatus.

  FIG. 4 is a block diagram illustrating an example of a configuration of the scheduling unit 215 in the base station apparatus 200.

  The reception quality of each channel output from the reception quality information storage unit 214 is input to the priority determination unit 241 and the allocation determination unit 242. The moving speed measurement result output from the moving speed storage unit 218 is input to the priority determination unit 241.

  The priority determination unit 241 determines each frequency in each terminal station apparatus based on either the (center) frequency or the carrier frequency of each frequency band to which each channel belongs, or the (center) frequency of each channel, and the moving speed measurement result. Determine and output channel assignment priority. At this time, it is determined so that the allocation priority of the channel having the lower frequency becomes higher.

  Alternatively, in addition to the above, the priority determination unit 241 may determine the channel to which the downlink data addressed to each terminal station device is assigned in the previous assignment result, or the frequency band to which the channel belongs or the channel to which the carrier frequency belongs. You may determine so that an allocation priority may become high. By doing so, the probability that the channel to which downlink data addressed to each terminal station device was assigned last time, or the frequency band to which the channel belongs or the channel belonging to the carrier frequency will be increased, will be increased by the base station device. Frequent switching of the channel, frequency band, and carrier wave frequency allocated to the terminal station apparatus is suppressed, and the processing required for the switching can be reduced and the fluctuation of interference given to other peripheral systems can be reduced.

  The allocation determination unit 242 determines channel allocation in consideration of the allocation priority determined by the priority determination unit 241. At that time, based on the amount of downlink data addressed to each terminal station device and the required quality (Quality of Service: QoS, allowable delay time, minimum transmission rate, etc.) You may decide. Furthermore, the allocation determination unit 242 selects the modulation scheme and error correction coding rate of each channel based on the allocation result of each channel and the reception quality information on the channel of the allocated terminal station apparatus, and The allocation result and the selection result of the modulation scheme and coding rate of each channel are output as scheduling information.

FIG. 8 is a graph showing the relationship between the movement speed and the correlation between the propagation path at a certain time t _{0 and} the propagation path after time t ₀ has elapsed.

As shown in FIG. 8, the correlation between the propagation paths at time t ₀ and time t ₀ + t (hereinafter simply referred to as propagation path correlation) decreases as the movement speed increases, and is uncorrelated when the movement speed exceeds a certain movement speed. It becomes. Further, the decrease in propagation path correlation becomes steeper as the carrier frequency increases. In FIG. 8, fc ₁ <fc ₂ <fc ₃ .

If the propagation path correlations corresponding to the carrier frequencies fc ₁ , fc ₂ , and fc ₃ at a certain moving speed v ₁ are r ₁₁ , r ₁₂ , and r ₁₃ , r ₁₁ > r ₁₂ > r _{13 as} shown in FIG. Become. Similarly, at the moving speed v _{2 where} v ₂ > v ₁ , r ₂₁ > r ₂₂ > r ₂₃ when the channel correlation is r ₂₁ , r ₂₂ , r _23. The difference (ratio) is different.

  Therefore, the priority determination unit 241 determines the allocation priority based on the difference in propagation path correlation at each carrier frequency with respect to the moving speed.

  In addition, when the moving speed is sufficiently low, there is no difference in the channel correlation at each carrier frequency, and when the moving speed is very high, the channel correlation at any carrier frequency becomes uncorrelated. The channel assignment priority is preferably determined to be equal. That is, a sufficiently small moving speed at which there is no difference in propagation path correlation is set as the first threshold, and similarly, a large moving speed at which propagation path correlation is uncorrelated at any carrier frequency is set as the second threshold. The scheduling unit makes the allocation priority equal in all channels when the moving speed measurement result is equal to or lower than the first threshold value or equal to or higher than the second threshold value.

  In addition, although it demonstrated using the carrier wave frequency above, you may apply by the (center frequency) of each frequency band or the (center frequency) of each channel.

  FIG. 5 is a diagram illustrating an example in which channel assignment is determined for two terminal station apparatuses T1 and T2 in a downlink composed of 16 channels. Here, it is assumed that the terminal station apparatus T1 is in a stationary state (moving speed 0 km / h) and the terminal station apparatus T2 is in a moving state (for example, moving speed 30 km / h). In addition, each terminal station apparatus selects 6 out of 16 channels, and notifies reception quality information regarding the selected 6 channels to the base station apparatus.

FIG. 5A is a diagram illustrating an example of channel arrangement in the frequency direction. Channel 4 belongs to the lowest carrier frequency fc ₁ from channel 1, channel 8 from the channel 5 in the center of the carrier frequency fc ₂ belongs, the highest carrier frequency fc ₃ are channel 16 from the channel 9 belongs. Hereinafter, an example will be described in which channels are grouped for each carrier frequency to which each channel belongs, and the allocation priority is determined based on the carrier frequency for each group.

  FIG.5 (b) is a figure which showed an example of the reception quality information which each terminal station apparatus notified to the base station apparatus. The terminal station apparatus T1 (solid line) and the terminal station apparatus T2 (dotted line) show the reception quality as shown in the figure for each of six channels.

Here, the priority determination unit 241 determines each channel of each terminal station device based on the input moving speed measurement result (the terminal station device T1 is 0 km / h, the terminal station device T2 is 30 km / h) and the carrier frequency. Determine the allocation priority for. First, since the terminal station apparatus T1 is in a stationary state, the allocation priority of all channels is set to “1” equally. Since the terminal station device T2 is in the moving state, the allocation priority of the group of channel 1 to channel 4 belonging to the lowest carrier frequency fc ₁ is set to “1”, and the channel 5 belonging to the next lowest carrier frequency fc ₂ is assigned. The allocation priority of the group of channel 8 is determined as “2”, and the allocation priority of the groups of channels 9 to 16 belonging to the highest carrier frequency fc ₃ is determined as “3”. The assignment priority determined as described above is shown in FIG.

  The allocation determining unit 242 determines channel allocation from the reception quality information illustrated in FIG. 5B and the allocation priority illustrated in FIG. Here, it is assumed that four channels need to be allocated to each terminal station apparatus.

(1) Among the channels for which the terminal station device T1 has notified the reception quality information, the channel 15 having the highest reception quality is selected from the channels having the highest allocation priority (that is, all the notified channels). Assigned to the terminal station device T1.

(2) The channel 2 having the highest reception quality is selected from the channels having the highest allocation priority (that is, channel 2 and channel 4) among the channels for which the terminal station apparatus T2 has notified the reception quality information. Assigned to station device T2.

(3) Similarly to (1), for the terminal station device T1, the channel 6 having the highest allocation priority among the unallocated channels (channels 1, 4, 6, 12) and the best reception quality is selected. Assigned to the terminal station device T1.

(4) In the same manner as in (2), for the terminal station device T2, the channel 4 having the highest allocation priority among unallocated channels (channel 4) and the best reception quality is allocated to the terminal station device T2. .

(5) Similarly to (1), for the terminal station apparatus T1, the channel 12 having the highest allocation priority (channels 1 and 12) among the unallocated channels and the best reception quality is assigned to the terminal station apparatus T1. Assign to.

(6) In the same manner as (2), for the terminal station apparatus T2, the channel 8 having the highest allocation priority (channel 8) and the best reception quality among the unallocated channels is allocated to the terminal station apparatus T2. .

(7) In the same manner as (1), for the terminal station apparatus T1, the channel 1 having the highest allocation priority among unallocated channels (channel 1) and the best reception quality is allocated to the terminal station apparatus T1. .

(8) In the same manner as (2), for the terminal station apparatus T2, the channel 10 having the highest allocation priority (channel 10) and the best reception quality among the unallocated channels is allocated to the terminal station apparatus T2. .

  Based on the above result, channel assignment is as shown in FIG.

  The assignment determination unit 242 further selects the modulation scheme and coding rate of the assigned channel based on the reception quality information corresponding to the assigned channel.

  In the above example, the procedure for starting channel assignment of the terminal station apparatus T1 and allocating channels one by one alternately with the terminal station apparatus T2 has been described. However, the amount of downlink data addressed to each terminal station apparatus The priority order between the terminal station apparatuses may be determined based on the required quality, and the channel may be allocated from the terminal station apparatus having a higher priority order.

  As described above, according to the present embodiment, the base station apparatus allocates channels from the channels arranged in a plurality of frequency bands to each terminal station apparatus based on the reception quality information reported from each terminal station apparatus. When deciding, based on the moving speed of each terminal station device and either the (center) frequency or the carrier frequency of each frequency band to which each channel belongs, or the (center) frequency of each channel, The terminal station apparatus allocation is determined. As a result, even for channels having the same reception quality, it is possible to assign channels in consideration of the channel fluctuation speed according to the frequency of each channel, and downlink data with higher stability (good error rate characteristics). Communication can be realized.

[Second Embodiment]
Next, a communication technique according to the second embodiment of the present invention will be described. The configuration of terminal station apparatus 300 in the present embodiment is the same as that in FIG. Further, the configuration of the base station apparatus 200 is different from the configuration of the scheduling unit 215 in FIG. 2, and the other configurations are the same. Hereinafter, a different part from 1st Embodiment is demonstrated.

  FIG. 6 is a block diagram showing an example of a configuration of scheduling section 215 of base station apparatus 200 in the present embodiment.

  The reception quality of each channel output from the reception quality information storage unit 214 is input to the priority determination unit 241 and the weight multiplication unit 262. The moving speed measurement result output from the moving speed storage unit 218 is input to the priority determination unit 241.

  The priority determination unit 241 determines whether each terminal station apparatus uses the (center) frequency or carrier frequency of each frequency band to which each channel belongs, or the (center) frequency of each channel, and the moving speed measurement result. The allocation priority of each channel is determined and output. At this time, it is determined so that the allocation priority of the channel having the lower frequency becomes higher. Further, it is determined that the allocation priority of the channel to which the downlink data addressed to each terminal station device is allocated in the previous allocation result, or the frequency band to which the channel belongs or the channel to which the carrier frequency belongs is higher. Also good.

  The weight calculation unit 261 calculates a weighting factor by which the reception quality of each channel is multiplied according to the allocation priority of each channel determined by the priority determination unit 241. The weight multiplication unit 262 multiplies the reception quality of each channel by the weight coefficient of each channel calculated by the weight calculation unit 261, and outputs the weighted reception quality.

  The allocation determination unit 263 determines channel allocation based on the weighted reception quality. Furthermore, the allocation determination unit 263, based on the allocation result of each channel and the reception quality information or weighted reception quality in the channel of the allocated terminal station apparatus, the modulation scheme and error correction coding rate of each channel And the channel allocation result and the selection result of the modulation scheme and coding rate of each channel are output as scheduling information.

  FIG. 7 is a diagram illustrating an example in which channel assignment is determined for two terminal station apparatuses T1 and T2 in a downlink composed of 16 channels. Here, as in the case of FIG. 5 in the first embodiment, the terminal station apparatus T1 is in a stationary state (moving speed 0 km / h), and the terminal station apparatus T2 is in a moving state (for example, moving speed 30 km / h). Assume that In addition, each terminal station apparatus selects 6 out of 16 channels, and notifies reception quality information regarding the selected 6 channels to the base station apparatus.

  FIG. 7B is a diagram illustrating an example of reception quality information that each terminal station apparatus has notified to the base station apparatus. The terminal station apparatus T1 (solid line) and the terminal station apparatus T2 (dotted line) each show the reception quality as shown in the figure for six channels.

Here, the priority determination unit 241 determines each of the terminal station devices based on the input moving speed measurement result (the terminal station device T1 is 0 km / h, the terminal station device T2 is 30 km / h) and the carrier frequency. Determine the allocation priority for the channel. First, since the terminal station apparatus T1 is in a stationary state, the allocation priority of all channels is set to “1” equally. Since the terminal station device T2 is in the moving state, the allocation priority of the group of channel 1 to channel 4 belonging to the lowest carrier frequency fc ₁ is set to “1”, and the channel 5 belonging to the next lowest carrier frequency fc ₂ is assigned. The allocation priority of the group of channel 8 is determined as “2”, and the allocation priority of the group of channels 9 to 16 belonging to the highest carrier frequency fc ₃ is determined as “3”, which is the lowest. The determination result of the allocation priority is the same as the result shown in FIG.

  The weight calculation unit 261 calculates a weight coefficient as shown in FIG. 7C according to the above allocation priority.

  The weight multiplier 262 multiplies the reception quality of each channel shown in FIG. 7B by the weight of FIG. 7C, and calculates the weighted reception quality of FIG. 7D.

  The allocation determining unit 263 determines channel allocation for each terminal station apparatus based on the weighted reception quality of FIG. For example, when it is necessary to assign four channels to each terminal station apparatus, the procedure for alternately allocating one channel from each channel having good weighted reception quality for each terminal station apparatus is as follows, for example: Become.

(1) Of the channels for which the terminal station device T1 has notified the reception quality information, the channel 15 having the highest (good) weighted reception quality is allocated to the terminal station device T1.

(2) Of the channels for which the terminal station device T2 has notified the reception quality information, the channel 2 having the highest weighted reception quality among the unassigned channels is allocated to the terminal station device T2.

(3) Of the channels for which the terminal station apparatus T1 has notified the reception quality information, the channel 6 having the highest weighted reception quality among the unallocated channels is allocated to the terminal station apparatus T1.

(4) Of the channels for which the terminal station apparatus T2 has notified the reception quality information, the channel 4 with the highest weighted reception quality among the unallocated channels is allocated to the terminal station apparatus T2.

(5) Of the channels for which the terminal station apparatus T1 has notified the reception quality information, the channel 12 having the highest weighted reception quality among the unassigned channels is allocated to the terminal station apparatus T1.

(6) Of the channels for which the terminal station apparatus T2 has notified the reception quality information, the channel 8 having the highest weighted reception quality among the unassigned channels is allocated to the terminal station apparatus T2.

(7) Of the channels for which the terminal station apparatus T1 has notified the reception quality information, the channel 1 having the highest weighted reception quality among the unassigned channels is allocated to the terminal station apparatus T1.

(8) Of the channels for which the terminal station apparatus T2 has notified the reception quality information, the channel 10 having the highest weighted reception quality among the unassigned channels is allocated to the terminal station apparatus T2.

  As a result of the assignment based on the above assignment criteria, the channel assignment is as shown in FIG.

  Assignment determining section 263 further selects the modulation method and coding rate of the assigned channel based on the reception quality information or weighted reception quality corresponding to the assigned channel.

  In the above example, the procedure for starting channel assignment of the terminal station apparatus T1 and allocating channels one by one alternately with the terminal station apparatus T2 has been described. However, the amount of downlink data addressed to each terminal station apparatus The priority order between the terminal station apparatuses may be determined based on the required quality, and the channel assignment may be performed from the terminal station apparatus having a higher priority order.

  As described above, according to the present embodiment, based on the reception quality information reported from each terminal station apparatus, the base station apparatus allocates channels from channels arranged in a plurality of frequency bands to each terminal station apparatus. To each channel based on the moving speed of each terminal station device and either the (center) frequency or the carrier frequency of each frequency band to which each channel belongs, or the (center) frequency of each channel. Allocation of each terminal station apparatus is determined. As a result, even for channels having the same reception quality, it is possible to assign channels in consideration of the channel fluctuation speed according to the frequency of each channel, and downlink data with higher stability (good error rate characteristics). Communication can be realized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, a system will be described in which base station apparatus 200 and terminal station apparatus 300 each include a plurality of antennas and perform communication by switching a plurality of transmission modes in the downlink. Examples of the transmission mode include transmission diversity and MIMO (Multiple Input Multiple Output) transmission.

  The terminal station device 300 is basically the same as the case of FIG. 3 except that a plurality of antennas are provided. The configuration of the base station apparatus 200 is basically the same as the configuration shown in FIG. 2 except that a plurality of antennas are provided. However, the scheduling unit 215 has the above-described configuration for each terminal station apparatus included in the downlink control information. Transmission mode information indicating the transmission mode is further input.

  The scheduling unit 215 according to the present embodiment, for the terminal station apparatus whose transmission mode information indicates transmission diversity, (center) frequency or carrier frequency of each frequency band to which each channel belongs, or ( Based on one of the (center) frequencies, the allocation priority is determined so that more channels are allocated from among the lower frequency channels.

  For the terminal station apparatus in which the transmission mode information indicates MIMO, the allocation priority is determined so that more channels are allocated from the higher frequency channels.

  In general, in a system in which transmission modes are switched using a plurality of transmission / reception antennas, if the moving speed of the terminal station device is fast, propagation path fluctuations are severe, so transmission diversity is aimed at the diversity effect between the antennas. Is selected as the transmission mode, and when the moving speed of the terminal station apparatus is slow, MIMO is selected as the transmission mode for high-speed transmission.

  As described above, according to the present embodiment, the base station apparatus allocates channels from the channels arranged in a plurality of frequency bands to each terminal station apparatus based on the reception quality information reported from each terminal station apparatus. When deciding, depending on the downlink transmission mode, either the moving speed of each terminal station, the (center) frequency or carrier frequency of each frequency band to which each channel belongs, or the (center) frequency of each channel Based on the above, assignment of each terminal station apparatus to each channel is determined. As a result, it is possible to preferentially assign an appropriate channel according to the transmission mode, and it is possible to realize more efficient downlink data communication (good error rate characteristics or high transmission rate).

  As described above, in each of the embodiments described above, the downlink transmission system is a multicarrier transmission system (particularly, an OFDMA transmission system), the channel configuration includes at least one subcarrier, and the unit of reception quality information is Downlink adaptive scheduling (assignment of channels to terminal stations) and adaptive modulation: In a cellular system that is per channel or per resource block obtained by further dividing the channel in the time direction, it is converted into pilot symbols as reception quality. The present invention has been exemplarily described using the SINR calculated based on the above.

  However, the modulation scheme, channel configuration, reception quality information and adaptive modulation unit, adaptive scheduling, and reception quality to which the present invention can be applied are not limited to the above.

  For example, an MC-CDMA (Multi Carrier-Code Division Multiple Access) system using spreading technology as a downlink transmission system is used, and the unit of adaptive modulation and adaptive scheduling is SDMA (Space Division Multiple Output Multiple Output) or the like. In other systems that perform communication using a plurality of channels such as a plurality of channels indicated by transmission antennas or eigenmodes, a plurality of code channels in CDMA, or a combination of these channels in multiple access (space division multiple access) Even in such a case, the present invention can be applied to a system in which reception quality may be different for each channel.

As reception quality,
1) RSSI (Received Signal Strength Indicator), SNR, SIR (Signal to Interference power Ratio), CNR (Carrier to Noise power Ratio), CIR (Carrier to Interference) power ratio: carrier power to interference power ratio), CINR (Carrier to Interference plus Noise power Ratio: carrier power to interference power and noise power ratio), and other indicators indicating reception quality in relation to received signal power and carrier power,

  2) MCS (Modulation and Coding Scheme), which is a combination of a modulation scheme and a channel coding rate, or an index related to a transmission rate such as a modulation parameter selected according to a propagation path state such as a modulation parameter such as a transmission rate. For example, there is no particular limitation.

  Each of the above embodiments is a communication system that employs FDD (Frequency Division Duplex) composed of a base station apparatus and a terminal station apparatus, and is adaptive modulation of OFDM in downlink communication. A system is assumed, and a system that does not perform OFDM and adaptive modulation in uplink communication is assumed, but is not limited thereto.

  Furthermore, the present invention is applied to wireless communication devices in which one of a plurality of wireless communication devices performs a scheduling function and adaptive modulation, and another wireless communication device can execute a reception quality information transmission function. can do.

  In addition, between the two wireless communication devices, the side that notifies the reception quality information of the channel (the side that has the reception quality information transmission function) is the terminal station device, and transmission to each terminal station device based on the notified reception quality information Although the side that performs adaptive modulation by assigning data to each channel (the side that performs the scheduling function) has been described as a base station apparatus, a single wireless communication apparatus may have both functions.

  In this specification, a wireless communication device is a device that performs wireless communication, and includes, for example, a base station device, a terminal station device, a wireless device, a portable terminal station device, a mobile phone, and the like.

  The present invention is applicable to a communication device.

It is the figure which showed an example of the frequency arrangement | positioning of the channel of a downlink in the communication technique in the 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the base station apparatus in this Embodiment. It is a functional block diagram which shows the schematic structural example of the terminal station apparatus in this Embodiment. It is a block diagram which shows an example of a structure of the scheduling part in a base station apparatus. It is a figure which shows an example in the case of deciding channel allocation with respect to two terminal station apparatus T1 and T2 in the downlink which consists of 16 channels. It is a block diagram which shows an example of a structure of the scheduling part of the base station apparatus in the 2nd Embodiment of this invention. It is a figure which shows an example in the case of deciding channel allocation with respect to two terminal station apparatuses T1 and T2 in the downlink which consists of 16 channels. The correlation between the propagation path in after the elapse of the channel and time t ₀ from time t at a certain time t _0, is a graph showing the moving speed, the relationship.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 200 ... Base station apparatus, 201 ... 1st encoding part, 202 ... 2nd encoding part, 203 ... 1st modulation part, 204 ... 2nd modulation part, 205 ... Pilot production | generation part, 206 ... Mapping part 207: Frequency time conversion unit 208: GI (Guard Interval) insertion unit 209 ... Radio transmission unit 210 ... Antenna unit 211 ... Radio reception unit 212 ... Demodulation unit 213 ... Decoding unit 214 ... reception quality information storage section, 215 ... scheduling section, 216 ... pilot separation section, 217 ... movement speed measurement section, 218 ... movement speed storage section, 300 ... terminal station apparatus, 301 ... antenna section, 302 ... radio reception section, 303 GI removal unit, 304 ... time frequency conversion unit, 305 ... demapping unit, 306 ... first demodulation unit, 307 ... second demodulation unit, 308 ... reception quality measurement unit, 309 ... first Decoding unit, 310 ... second decoding unit, 311 ... channel selector, 312 ... reception quality information generating section, 313 ... encoding unit, 314 ... modulating unit, 315 ... wireless transmission unit, 316 ... pilot insertion unit.

Claims (15)

A base station device that performs communication by allocating channels from a plurality of channels arranged at a plurality of frequencies to a plurality of terminal station devices,
A radio reception unit that receives reception quality information representing reception quality in a part or all of the plurality of channels from each of the terminal station devices;
A base station apparatus comprising: a scheduling unit that determines a channel to be allocated to communication to each terminal station apparatus from among the plurality of channels based on a frequency of each channel and the reception quality information. The scheduling unit includes
Based on the frequency of each channel, the allocation priority of each channel of each terminal station apparatus is determined, and from among the plurality of channels based on the reception quality information and the allocation priority of each terminal station apparatus The base station apparatus according to claim 1, wherein a channel to be allocated for communication to each terminal station apparatus is determined. The scheduling unit includes
The base station apparatus according to claim 2, wherein a plurality of channels having close frequencies are grouped and the allocation priority is determined for each group. The scheduling unit includes
3. The assignment priority of a channel or a group of channels arranged at a lower frequency is set higher than the assignment priority of a channel or a group of channels arranged at a higher frequency. Or the base station apparatus of 3. Furthermore, a moving speed measuring unit for measuring the moving speed of each terminal station device is provided,
5. The base station according to claim 2, wherein the scheduling section further determines an allocation priority of each channel of each terminal station apparatus based on the moving speed measurement result. apparatus. The scheduling unit includes
The said allocation priority is made equal in all the channels, when the said moving speed measurement result is below a 1st threshold value or more than a 2nd threshold value larger than the said 1st threshold value, The all-channels are equal. Base station device. The scheduling unit includes
The base station apparatus according to any one of claims 2 to 6, wherein the allocation priority of the channel allocated to each terminal station apparatus or the group to which the allocated channel belongs is set high. . The scheduling unit includes
A weighting factor of each channel is calculated based on the allocation priority, and the reception quality represented by the reception quality information of each channel is multiplied. Based on the multiplication result, the channel is transmitted from the plurality of channels to each terminal station apparatus. The base station apparatus according to any one of claims 2 to 7, wherein a channel to be allocated is determined. A base station apparatus that performs communication using a plurality of transmission antennas by allocating channels from a plurality of channels arranged at a plurality of frequencies to a plurality of terminal station apparatuses,
A radio reception unit that receives reception quality information representing reception quality in a part or all of the plurality of channels from each of the terminal station devices;
A scheduling unit for determining a channel to be allocated to communication to each terminal station device from among the plurality of channels based on a type of transmission mode using the plurality of transmission antennas, a frequency of each channel, and the reception quality information; A base station apparatus comprising: The scheduling unit includes
10. The base station apparatus according to claim 9, wherein, for a terminal station apparatus whose transmission mode is transmission diversity, the number of channels allocated to the terminal station apparatus is increased from among the low frequency channels. The scheduling unit includes
10. The base station apparatus according to claim 9, wherein the number of channels allocated to the terminal station apparatus among the high frequency channels is increased for the terminal station apparatus having the MIMO transmission mode. A communication system that performs communication from a base station apparatus to a terminal station apparatus using a plurality of channels arranged at a plurality of frequencies,
The base station device
A radio reception unit that receives reception quality information representing reception quality in a part or all of the plurality of channels from each of the terminal station devices;
A scheduling unit that determines a channel to be allocated to each terminal station apparatus from among the plurality of channels based on the frequency of each channel and the reception quality information;
The terminal station device
A reception quality measuring unit for measuring reception quality of the plurality of channels;
A reception quality information generating unit that generates reception quality information representing the reception quality measurement result in a part or all of the plurality of channels;
A wireless communication unit that transmits the reception quality information to the base station apparatus. A communication method for performing communication from a base station apparatus to a terminal station apparatus using a plurality of channels arranged at a plurality of frequencies,
The base station device
Receiving reception quality information representing reception quality in a part or all of the plurality of channels from each of the terminal station devices;
Determining a channel to be allocated to each terminal station device from among the plurality of channels based on the frequency of each channel and the reception quality information,
The terminal station device
Measuring reception quality of the plurality of channels;
Generating reception quality information representing the reception quality measurement results in some or all of the plurality of channels;
Transmitting the reception quality information to the base station apparatus.   A program for causing a computer to execute the method according to claim 13.   A computer-readable recording medium for recording the program according to claim 14.

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