JP2010114676A - Power allocating method for parallel channel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a power allocating method for parallel channels which can guarantee a constant transmission capacity for a channel having a preference to power allocation and partially magnify a system transmission capacity. <P>SOLUTION: When controlling transmission power of a plurality of parallel channels in which data transmission is performed between a transmission station (BS device) and a receiving station (MS), the minimum required power is allocated to each of the parallel channels to all of the plurality of parallel channels, and dump power after allocating the minimum required power is further allocated to all of the plurality of parallel channels according to the water filling principal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power allocation method for parallel channels applied to a transmitting-side radio communication base station apparatus.

In recent years, there has been an increasing demand for wireless broadband high-speed and large capacity. For example, in cellular systems, it is required to maximize cell communication capacity.
Conventionally, a data transmission / reception technique using a parallel channel is well known.

  In particular, the entire system band is divided into a plurality of frequency blocks (called subcarriers), and data is allocated to each block, such as OFDM / OFDMA (Orthogonal Frequency Division Multiplexing / Orthogonal Frequency Division Multiple Access). A multi-carrier system that forms a transmission path and a MIMO (Multiple-Input Multiple-Output) system that forms a spatial parallel transmission path using a plurality of transmitting antennas and a plurality of receiving antennas are used as means for expanding cell communication capacity. It is an effective means.

A system having these parallel channels can control radio resources flexibly, and can improve cell communication capacity by appropriately scheduling radio resources.
In the case of a single site, a transmission power limit is generally provided for each base station (BS: Base Station), and in order to examine an optimal solution for a transmission power allocation method, channel quality (signal power gain), It is necessary to perform adaptive control according to the policy regarding the modulation degree and communication quality.

In recent years, as a multi-site, a plurality of base station cooperation schemes in which a plurality of base stations share user data and control information and cooperatively transmit data have been studied.
In this method, since the transmission power allocation of a certain BS affects the power allocation and performance of other BSs, adaptive power control according to the situation is required.

In view of the above background, there has been proposed a power allocation method for parallel channels in which priority power allocation is performed for a specific data class of parallel channels (see, for example, Patent Document 1).
In transmission power allocation to parallel channels, equal allocation (power equal distribution) is common, but equal allocation has the following problems.

That is, the channel quality in the cell supported by the BS is not uniform and varies depending on the position of a mobile station (MS: Mobile Station) serving as a receiving station. Therefore, when transmission power is equally allocated to all MSs Communication quality is directly proportional to channel quality.
However, since the desired throughput and BER (Bit Error Rate) of each MS depend on the type of data communication and QoS (Quality of Service) of that MS, equal distribution is not always appropriate, and cell communication capacity maximization is not possible. Also not appropriate in terms of aspects.

  Also, in equal distribution, low-quality channels are transmitted at a low rate, and a transmission capacity comparable to that of high-quality channels cannot be obtained, so when multiple MSs share these parallel channels, There is a problem in that the transmission capacity difference is large and the communication quality between MSs is imbalanced, and high-speed and large-capacity data transmission is impossible for MSs with low channel quality.

Furthermore, when a plurality of data connections share a parallel channel, a transmission capacity difference occurs between the connections, and the same imbalance occurs.
In addition, when an FEC data block divided by using a plurality of spatial parallel channels is transmitted in a certain MS, there is a problem that an entire FEC data block cannot be decoded due to an error generated in a specific channel. It will occur.
Therefore, the BS needs to adaptively perform power distribution in consideration of the desired throughput, BER, and channel quality of each parallel channel.

On the other hand, in the power distribution for the parallel channels, the water injection theorem distribution is given as a power allocation method that maximizes the total transmission capacity.
However, power allocation according to the water injection theorem allocates more power to channels with good channel quality and allocates less power to channels with poor channel quality, so the transmission capacity of channels with poor channel quality. Is degraded compared to even distribution. In some cases, no power is allocated and no communication opportunity is allocated.

  Such an allocation method based on the water injection theorem is exclusive control in which poor quality channels are discarded in order to maximize the total transmission capacity of parallel channels, and may not be appropriate in an actual communication system.

Furthermore, the characteristics and application range of multi-site power distribution (multiple base station cooperation method) will be described.
The multiple base station cooperation method is a method for improving user throughput by sharing user data and control information and cooperatively using antennas with different installation locations.

  However, the multi-base station cooperative scheme is effective at a position where radio waves of the same quality are received from a plurality of BSs such as a cell edge region, so that the channel quality may be worse than that of other MSs. Therefore, there is a problem that only an insufficient transmission capacity can be obtained by power allocation equally for each MS or power allocation based on the water injection theorem, and adaptive power control is required.

JP 2006-237897 A

  In the conventional power allocation method for parallel channels, although adaptive power control is required, a method for dealing with this has not been proposed, and there is a problem that proper allocation cannot be realized. .

The present invention has been made to solve the above-mentioned problems. In a single BS, a certain transmission capacity is guaranteed for a channel having a priority of power allocation, and a system transmission capacity is partially increased. The object is to obtain a power allocation method for parallel channels that can be maximized.
Also, in the cooperative scheme of multiple BSs, by guaranteeing a certain transmission capacity, maximizing a partial system transmission capacity, and adjusting power distribution among multiple BSs for the channels to be coordinated An object of the present invention is to obtain a power allocation method capable of realizing a transmitting-side radio communication base station apparatus and a cooperative control apparatus.

  A power allocation method for parallel channels according to the present invention is a power allocation method for controlling transmission power of a plurality of parallel channels in which data transmission is performed between a transmitting station and a receiving station, and for all of the plurality of parallel channels. The minimum required power of each parallel channel is allocated, and the surplus power after the minimum required power is allocated is further allocated to all of the plurality of parallel channels according to the water injection theorem.

  According to the present invention, it is possible to guarantee a certain transmission capacity for a channel having power allocation priority and partially maximize the system transmission capacity.

Embodiment 1 FIG.
Hereinafter, a power allocation method for parallel channels according to Embodiment 1 of the present invention will be described in detail with reference to the drawings.
Here, a radio base station apparatus to which the power allocation method for parallel channels is applied will be described as an example. The present invention is not limited to the following description.

FIG. 1 is a block diagram showing a radio base station apparatus to which a power allocation method for parallel channels according to Embodiment 1 of the present invention is applied, and shows a configuration of a radio (transmitting station).
In FIG. 1, a BS apparatus 100 serving as a transmission station includes a QoS detection unit 101, a scheduling unit 103, a resource mapping unit 104, a baseband processing unit 105, and a level measurement unit 106.

The QoS detection unit 101 detects a QoS (Quality of Service) class from the IP packet 107, and generates User Data (user data) 111 and QoS information 112.
The scheduling unit 103 performs a mapping instruction using a channel quality report message 110 (described later), User Data 111, and QoS information 112.

The resource mapping unit 104 performs resource mapping from the User Data 111 to the logical radio frame 108a in accordance with an instruction from the scheduling unit 103.
The baseband processing unit 105 performs radio signal processing of the logical radio frame 108a mapped by the resource mapping unit 104, and generates a physical radio frame 108b.

Further, the baseband processing unit 105 performs radio signal processing of a received signal (channel quality report message 109) obtained from an MS (receiving station) in FIG.
The radio signal processing of User Data 111 performed by the baseband processing unit 105 includes MIMO encoding, MIMO decoding, OFDM processing by IDFT (Inverse Discrete Fourier Transfer, DFT (Discrete Fourier Transfer), and the like.

In accordance with an instruction from the scheduling unit 103, the level measurement unit 106 aggregates the channel quality measured by each MS and generates a channel quality report message 110.
Note that the channel quality aggregated by the level measurement unit 106 includes CINR (carrier power vs. interference signal power and noise ratio, etc.) and RSSI (Received Signal Strength Indicator).

In the BS device 100 shown in FIG. 1, first, the connection of the IP packet 107 is separated for each QoS by the QoS separation unit 101.
Next, the scheduling unit 103 determines User Data 111 and transmission power level to be mapped for each frame based on the QoS information 112 and the channel quality report message 110.

  Here, the channel quality report message 110 is CINR or RSSI information extracted from the channel quality report message 109 collected from each MS after being subjected to radio signal processing by the baseband processing unit 105 and then extracted by the level measurement unit 106. .

FIG. 2 is a block diagram showing in detail the scheduling unit 103 in FIG.
In FIG. 2, the scheduling unit 103 includes a User Data storage unit 131, a power allocation unit 203, a guarantee CINR determination unit 207, and a priority calculation unit 211.

The User Data storage unit 131 holds the User Data 111 from the QoS detection unit 101 using a queue 130 and inputs the stored User Data 205 to the resource mapping unit 104.
The priority calculation unit 211 determines the priority of the User Data 111 based on the QoS information 112 from the QoS detection unit 101, and generates the priority information 210.

The guarantee CINR determination unit 207 determines the guarantee CINR information 212 based on the priority information 210.
The power allocation unit 203 determines power allocation for each User Data based on the channel quality report message 110 from the level measurement unit 106 and the guarantee CINR information 212 from the guarantee CINR determination unit 207, and uses the power allocation information 208. Is input to the resource mapping unit 104.

The priority information 210 is determined by the priority calculation unit 211 based on the QoS information 112 of each User Data 111 as described above.
In addition, the lease mapping unit 104 maps the User Data 205 to the logical radio frame 108a based on the power allocation information 208 determined by the power allocation unit 203.

FIG. 3 is an explanatory diagram showing a configuration example of a DL radio frame 140 of, for example, IEEE 802.16e, and illustrates a DL (Down Link) PUSC frame configuration (or DL AMC frame configuration) in OFDM / OFDMA as an example.
FIG. 6 shows an arrangement example of MSs (receiving stations) 181 to 183 corresponding to the frame of FIG. Note that the frame configuration shown in FIG. 3 and the MS arrangement shown in FIG. 6 are merely examples, and do not limit Embodiment 1 of the present invention.

In FIG. 3, the DL radio frame 140 in IEEE 802.16e includes a preamble, an FCH, a DL-MAP, a UL-MAP, and DL bursts (bursts) 141 to 143.
Here, the parallel channel is treated as “a subchannel in which a plurality of subcarriers in OFDMA are collected”.

Since each DL Busrt 141-143 uses a different frequency resource, it is a parallel channel without interference.
The transmission power of DL Burst 141 is PT1, the transmission power of DL Burst 142 is PT2, the transmission power of DL Burst 143 is PT3, and the respective transmission powers PT1 to PT3 [dBm] are the power allocation unit 203 in FIG. Determined by.

Next, the partial optimal allocation method (distribution method) will be described with reference to the explanatory diagrams of FIGS.
Here, a power allocation method including two steps, that is, power allocation that guarantees the minimum transmission rate (step 1) and surplus power allocation (step 2) for all DL bursts 141 to 143 will be described.

First, the power allocation method (step 1) in guaranteeing the minimum transmission rate will be described.
4 and 5 are explanatory diagrams showing examples of power allocation in the first embodiment of the present invention corresponding to the DL radio frame 140. FIG.
FIG. 4 shows the minimum transmission rate guaranteed power allocation 160, where “PT1_1” 161 is the allocated power amount to DL Burst 141, “PT2_1” 162 is the allocated power amount to DL Burst 142, and “PT3_1” 163 is DL This is the amount of power allocated to the Burst 143.

These allocated power amounts “PT1_1” 161 to “PT3_1” 163 are power amounts that guarantee the minimum transmission rate of User Data allocated to each DL Burst 141 to 143.
For example, FIG. 6 shows an arrangement of MSs 181 to 183 in a cell (cell) 184 including a BS device (base station) 100, where DL Bust 141 is data to MS 181 and DL Burst 142 is data to MS 182. DL Burst 143 is data to MS 183.

As shown in FIG. 6, the propagation distance from the BS device 100 becomes longer in the order of MS181, MS182, and MS183, and the channel quality generally deteriorates in proportion to the transmission path distance.
Minimum rate guaranteed power amount (allocated power amount) “PT1_1” 161, “PT2_1” 162, “PT3_1” 163 allocated to each DL Burst 141 to 143 is a channel quality report message 110 (see FIGS. 1 and 2) in each MS 181 to 183. Reference) and the minimum transmission rate of User Data of each MS 181 to 183.

  Here, the channel quality report message 110 is CINR, RSSI information, etc. estimated on the MS side using the preamble or pilot signal in the DL radio frame 140, and the MSs 181 to 183 receive feedback (in the UL frame) It is obtained by notifying the BS apparatus 100 using an MS status report channel such as a Feedback channel.

It is also possible to measure the DL channel quality on the BS side using the UL transmission path.
Further, the minimum transmission rate of the User Data 111 is set based on the QoS information 112 of the User Data 111, the required CINR of the minimum rate modulation degree, and the like.
Specifically, it is conceivable that the modulation degree of the minimum transmission rate in the target wireless system is the amount of power that achieves the desired BER / PER.

Next, the surplus power allocation method (step 2) will be described.
In step 2, in order to maximize the cell communication capacity, the power sum allocated to each MS 181 to 183 in step 1 is subtracted from the BS total transmission power, and the surplus power obtained by this subtraction is injected into water. Reallocate power according to the theorem.

FIG. 5 is an explanatory diagram showing the surplus power reassignment 170. The reassigned power amounts “PT1_2” 171 to “PT3_2” 173 to the DL Bursts 141 to 143 and the power adjustment amounts “1 / γ1” 174 to “1 /” are shown. Water (water) level 1 / η composed of γ3 ”176.
The power PT_r to be reassigned is expressed by the following formula (1) using the BS total transmission power PT.

    PT_r = PT− (PT1_1) − (PT2_1) − (PT3_1) (1)

  Therefore, as shown in FIG. 5, “PT1_2” 171 is set as the reallocation power amount to DL Burst 141, “PT2_2” 172 is set as the reallocation power amount to DL Burst142, and “PT3_2” 173 is sent to DL Burst143. Assuming the reallocation power amount, the total allocated power to DL Burst 141 is PT1_1 + PT1_2, the total allocated power to DL Burst 142 is PT2_1 + PT2_2, and the total allocated power PT3_1 + PT3_2 to DL Burst 143. The relationship of the following formula (2) is established between the total reallocation power PT_R.

    PT_R = (PT1_2) + (PT2_2) + (PT3_2) (2)

  The power adjustment amount 174 is the power adjustment amount in the DL burst 141, and the DL burst 141 value γ1 is a value based on the channel quality report message 110 for the MS 181. It is.

Similarly, the power adjustment amount 175 is a power adjustment amount in the DL burst 142, and the power adjustment amount 176 is a power adjustment amount in the DL burst 173.
These power adjustment amounts 174 to 176 are reciprocals of the channel quality, and are small when the channel quality is good and large when the channel quality is bad.

  The surplus power is allocated to each subchannel subjected to power adjustment so that the water level 1 / η in FIG. 5 is the same so as to satisfy the following expression (3).

(PT1_2) + (1 / γ1) = (PT2_2) + (1 / γ2)
= (PT3_2) + (1 / γ3) (3)

In general, equation (3) is referred to as Water Level in the water injection theorem.
The power adjustment amounts 174 to 176 may be values obtained by adding the powers “PT1_1” 161 to “PT3_1” 163 to each subchannel in the minimum transmission rate guaranteed power allocation 160 (FIG. 4).
In this case, the correction values 1 / γ1 ′ to 1 / γ3 ′ of the power adjustment amounts 174 to 176 are expressed by the following equations (4) to (6).

1 / γ1 ′ = (1 / γ1) + (PT1_1) (4)
1 / γ2 ′ = (1 / γ2) + (PT2_1) (5)
1 / γ3 ′ = (1 / γ3) + (PT3_1) (6)

  In this way, after allocating power for guaranteeing the minimum transmission rate in Step 1, in Step 2, by performing power reassignment according to the water injection theorem that maximizes the cell communication capacity, the MS with poor channel quality can be handled. On the other hand, it is possible to partially maximize the cell communication capacity while guaranteeing a minimum transmission rate.

  That is, according to Embodiment 1 (FIGS. 1 to 6) of the present invention, when controlling the transmission power of a plurality of parallel channels in which data transmission is performed between BS apparatus (transmitting station) 100 and a receiving station. First, in step 1 (FIG. 4), the minimum transmission rate guaranteed power allocation 160 of each parallel channel is performed for all of the plurality of parallel channels (the minimum required power of each parallel channel is allocated).

Subsequently, in step 2 (FIG. 5), surplus power reassignment 170 is performed for all of the plurality of parallel channels (the surplus power after assigning the minimum required power to the water injection theorem (water level 1 / η)). Therefore, further allocation).
As a result, it is possible to guarantee a certain transmission capacity for all of the plurality of parallel channels and partially maximize the system transmission capacity.

Embodiment 2. FIG.
In the first embodiment, the minimum required power of each parallel channel is allocated in step 1 (FIG. 4). However, as shown in FIG. The required power may be allocated.

Hereinafter, a power allocation method (partial optimal allocation method) for parallel channels according to Embodiment 2 of the present invention will be described with reference to FIGS. 7 to 9 together with FIGS.
The radio base station apparatus to which the second embodiment of the present invention is applied is as shown in FIGS.

  In the power allocation method according to Embodiment 2 of the present invention, a subchannel to which User Data that is evaluated as having a high priority by the priority calculation unit 211 based on QoS information 112 of specific User Data (MS) is mapped. It consists of two steps: preferential power allocation 230 (FIG. 7) and surplus power reallocation (FIGS. 8 and 9).

  In step 1, the priority information 210 is first determined by the priority calculator 211 (FIG. 2), and then the guarantee CINR information 212 is determined by the guarantee CINR determiner 207 based on the determined priority. Further, the power allocation unit 203 preferentially allocates power that satisfies the determined guarantee CINR.

The priority information 210 at this time is determined based on the data communication type and the QoS information 112.
FIG. 7 is an explanatory diagram showing an example of the priority power allocation 230, and shows a case where priority power allocation is performed for the DL Burst 143 (MS183).
As shown in FIG. 7, when performing priority power allocation for the DL burst 143 (MS 183), the power “PT3_1” 231 that satisfies the priority allocation CINR information 212 is higher than other MSs (DL bursts 141, 142). Priority is assigned to DL Burst 143.

Subsequently, in step 2 (FIG. 8), reassignment 240 of surplus power “PT-PT3_1” is performed by subtracting the priority power allocation PT3_1 from the total transmission power PT.
In FIG. 8, transmission powers “PT1” 245 and “PT2” 246 for DL Bursts 141 and 142 are reassigned by surplus power “PT-PT3_1”.

In addition, since necessary power is already allocated to DL Burst 143 in Step 1 (FIG. 7), after additional power adjustment (PT3_1) is performed, the cell communication capacity is maximized. Allocate power according to the water injection theorem.
That is, for DL Burst 143, “already allocated power PT3_1” is added to “power adjustment amount based on channel quality (1 / γ3)” to obtain the total power adjustment amount.

  Therefore, as shown in FIG. 8, when the water level (Water Level) 1 / η is equal to or less than the overall power adjustment amount of the DL burst 143, the DL burst 143 is not subject to the surplus power reassignment according to the water injection theorem.

  On the other hand, as shown in FIG. 9, when the water level 1 / η is equal to or less than the overall power adjustment of the DL Burst 143, the DL Burst 143 is subject to the reallocation of surplus power according to the water injection theorem, and the reallocation power PT3_2 is Added.

  In this way, after assigning the required power PT3_1 to the User Data having a high priority in Step 1 (FIG. 7), the power according to the water injection theorem that maximizes the cell communication capacity in Step 2 (FIGS. 8 and 9). By allocating again to User Data having a high priority (FIG. 9), it is possible to partially maximize the cell communication capacity while securing the required power of the User Data having a high priority. is there.

  That is, according to the second embodiment (FIGS. 1 to 3 and FIGS. 7 to 9) of the present invention, the transmission power of a plurality of parallel channels in which data transmission is performed between the transmitting station and the receiving station is controlled. First, priority power allocation 230 is performed in step 1 (FIG. 7) (required power is allocated to a priority channel among a plurality of parallel channels).

Subsequently, in step 2 (FIGS. 8 and 9), surplus power reassignment 240, 250 is performed (the surplus power after the required power is allocated is assigned to all parallel channels including the priority channel according to the water injection theorem. To assign more).
Thereby, there exists an effect similar to the above-mentioned Embodiment 1.

Embodiment 3 FIG.
In Embodiments 1 and 2 (FIG. 1), a single BS apparatus 100 (single base station) is used as a transmitting station, but two (a plurality) arranged in parallel as shown in FIG. BS apparatuses 300 and 301 may be used.
The third embodiment of the present invention will be described below with reference to FIGS.

  FIG. 10 is a block diagram showing a radio base station apparatus to which the power allocation method for parallel channels according to Embodiment 3 of the present invention is applied, and a plurality of base stations in which two different BS apparatuses 300 and 301 can operate cooperatively. The radio | wireless machine structure which has a cooperation function (Full-Cooperation: F-Coop electric power distribution) is shown. Note that the number of BS devices that perform cooperative operation is not limited to two, and cooperation with an arbitrary number of BSs is possible.

10, BS apparatuses 300 and 301 having the same configuration include a channel state measurement unit 115 and a cooperative operation control unit 116 in addition to the same functional blocks 101 and 103 to 106 as those described above (see FIG. 1). ing.
In addition, a user data distribution unit 114 is connected to the QoS detection unit 101 in the BS devices 300 and 301.

The user data distribution unit 114 is a functional block necessary for a cooperative scheme in which a plurality of BS devices 300 and 301 share the same user data.
The cooperative operation control unit 116 is inserted between the level measurement unit 106 and the scheduling unit 103, and the channel state measurement unit 115 is inserted between the baseband processing unit 105 and the cooperative operation control unit 116.

The cooperative operation control units 116 in the BS devices 300 and 301 are connected so as to communicate with each other, and transmit and receive a cooperative operation control signal 113.
Thereby, the BS device 300 and the BS device 301 are configured to be capable of cooperative operation via the cooperative operation control unit 116.

In each BS apparatus 300, 301, the channel state measurement unit 115 measures the channel state to the MS (receiving station) and inputs the channel state to the cooperative operation control unit 116.
The cooperative operation control unit 116 generates control information necessary for cooperative operation with the other BS device based on the channel state information from the channel state measurement unit 115, and performs cooperative operation control with the other BS device. Exchange signal 113 (control information).

At this time, the channel state measurement unit 115 acquires more detailed channel information than the level measurement unit 106 based on the channel quality report message 109. Specifically, the channel response coefficient between transmission and reception is acquired.
Further, the cooperative operation control unit 116 exchanges the cooperative operation control signal 113 to enable cooperative operation between the BS device to which the cooperative operation control signal 116 belongs and the other BS device.

  10 shows a case where the user data distribution unit 114 exists outside the BS apparatuses 300 and 301, but the present invention is not limited to this configuration example. For example, one of a plurality of BS apparatuses ( Alternatively, some) may become a parent BS including the user data distribution unit 114 and distribute user data to other BS apparatuses.

In addition, although the cooperative operation control unit 116 is provided in each BS device 300 and 301 here, the cooperative operation control unit 116 may be provided outside the BS devices 300 and 301.
Further, one (or some) of the plurality of BS devices serves as a master station including the cooperative operation control unit 116, and the cooperative operation control signal is based on channel state information and scheduling information from other BS devices. A method of generating 113 may be adopted.

Next, the frame configuration in Embodiment 3 of the present invention will be described with reference to the explanatory diagram of FIG. 11A shows the frame configuration of the BS apparatus 300, and FIG. 11B shows the frame configuration of the BS apparatus 301.
In FIG. 11, as described above, DL PUSC frame configuration (or DL AMC frame configuration) in OFDM / OFDMA in the case of performing power control having a multi-base station cooperation function using an IEEE 802.16e radio frame. An example is shown.

  FIG. 12 shows an example of the arrangement of the MSs 351 to 355 corresponding to the frame of FIG. The frame configuration in FIG. 11 and the MS arrangement in FIG. 12 are merely examples, and do not limit Embodiment 3 of the present invention.

11A shows the BS device 300 and the DL radio frame 310 in IEEE 802.16e, and FIG. 11B shows the BS device 301 and the DL radio frame 311.
In FIG. 11A, the DL radio frame 310 is composed of a preamble, FCH, DL-MAP, UL-MAP, and DL bursts 321 to 323, as described above (FIG. 6). DL Burst 321 is a Burst that cooperates with the BS device 301.

  Similarly, in FIG.11 (b), DL radio frame 311 is comprised from preamble, FCH, DL-MAP, UL-MAP, and DL Burst 331-333. The DL Burst 331 is a Burst that cooperates with the BS device 300.

Here, the parallel channel is treated as “a subchannel in which a plurality of subcarriers in OFDMA are collected”.
Since each DL Busrt belonging to the same BS device uses different frequency resources, it is a parallel channel without interference, but interference from other BS devices using the same subchannel exists.

In FIG. 11A, the transmission power of DL Burst 321 transmitted by the BS apparatus 300 is PT1_1, the transmission power of DL Burst 322 is PT1_2, and the transmission power of DL Burst 323 is PT1_3.
Similarly, in FIG. 11B, the transmission power of DL Burst 331 is PT2_1, the transmission power of DL Burst 332 is PT2_2, and the transmission power of DL Burst 333 is PT2_3.

FIG. 12 shows an example of an MS arrangement corresponding to the DL radio frame shown in FIG.
In FIG. 12, MS 351 (corresponding to DL Burst 321 and DL Burst 331) exists in an area where BS device (base station) 300 and BS device 301 perform cooperative communication (F-Coop).

  Further, there are MS352 (corresponding to DL Burst 322) and MS353 (corresponding to DL Burst 323) in the cell 360, and MS 354 (corresponding to DL Burst 332) and MS 355 (corresponding to DL Burst 333) in the cell 361. ) And exist.

Next, an F-Coop weight will be described as a specific method according to the third embodiment of the present invention.
As described above, in the multiple base station cooperation method, there is a method (F-Coop) in which both the control information and the user information are shared between the BS apparatuses 300 and 301.

  The F-Coop method is referred to as a method using a big array antenna composed of antenna branches that are installed at spatially different positions by selecting a plurality of antenna branches belonging to different BS devices, and using this big array, Data is transmitted to 1MS.

  Furthermore, when using Precoding which gives a power weight and a phase weight in each BS apparatus, the power allocation rate between each BS apparatus is dependent on the said power weight. For example, consider that two base stations each have two antennas, which perform F-Coop. At this time, the number of antennas that can be used in the F-Coop is “4”.

Here, it is assumed that the power weight of each antenna is Wp11, Wp12, Wp21, and Wp22. In Wpij, “i” is a BS number, and “j” is an antenna number in each BS.
At this time, the allocated power to the BS apparatus 300 for the MS 351 in FIG. 12 is “Wp11 + Wp12”, and the allocated power to the BS apparatus 301 is “Wp21 + Wp22”.
In general, the power weight Wpij of each antenna determined by F-Coop is not an absolute value but a power allocation ratio between the antennas, and therefore absolute power allocation is performed separately.

Next, a specific method of equal power allocation (equal power distribution) in F-Coop will be described with reference to FIG.
Generally, the MS 351 (FIG. 12) to be F-Coop is often located in the edge region in the cells 360 and 361. Therefore, in the equal power distribution, the gain by the F-Coop for the MS in the cell edge region. Therefore, the required power that satisfies the desired throughput and BER according to the data communication type and QoS is preferentially allocated to the MS 351 subject to F-Coop.

FIG. 13A shows the power allocation (BS300 power allocation) 380 of the BS apparatus 300, and FIG. 13B shows the power allocation (BS301 power allocation) 381 of the BS apparatus 301.
In FIG. 13, DL Burst 321 in FIG. 13A and DL Burst 331 in FIG. 13B are Bursts to the MS 351 subject to F-Coop.
The power of each Burst is “PT1_1” 382 and “PT2_1” 383, which are represented by the following equations (7) and (8), respectively.

PT1_1 = α * (Wp11 + Wp12) (7)
PT2_1 = α * (Wp21 + Wp22) (8)

  However, in Expressions (7) and (8), α is a coefficient determined by the required power that satisfies the desired throughput, BER, and the like, and is preferentially assigned over Burst to the other MSs 352 to 355.

The surplus power of each BS apparatus 300 and 301 after priority allocation is reallocated according to the water injection theorem to those other than the MS 351 subject to F-Coop.
At this time, even if the water levels (Water Level) 1 / η1 and 1 / η2 according to the water injection theorem exceed PT1_1 or PT2_1, the power reassignment to the MS 351 subject to F-Coop is not performed.

As described above, according to Embodiment 3 (FIGS. 10 to 13) of the present invention, there are a plurality of BS apparatuses 300, 301 (transmitting stations) and MSs 351 to 355 (receiving stations). 301 (a plurality of transmitting stations) perform data transmission in a coordinated manner, and the same receiving station (F-Coop target) among the plurality of MSs 351 to 355 (receiving stations) from the BS devices 300 and 301 (a plurality of transmitting stations) MS 351) transmits cooperative data.
Thereby, even if it is a case where the some BS apparatus 300,301 is used, there exists an effect equivalent to above-mentioned Embodiment 1,2.

Embodiment 4 FIG.
Although not particularly mentioned in the third embodiment, it is necessary to consider whether to stop power adjustment (priority power allocation).
When the above-described precoding (giving power weights and phase weights) is used, a plurality of MSs can be spatially multiplexed within the DL Burst subject to F-Coop, but depending on the transmission path state and the precoding method, the interference component due to multiplexing May be dominant over noise, and increasing the power allocation has little effect.

For example, when the required CINR is not satisfied at the time of power allocation to all of the F-Coop target DL bursts, the priority burst allocation is not performed, and the F-Coop target DL bursts are set in the same manner as other DL bursts. deal with.
The determination regarding the presence / absence (execution / cancellation) of priority power allocation is not limited to the above criteria (whether or not the required CINR is satisfied), and the QoS information of the F-Coop target DL Burst and the other DL Burst QoS information. Therefore, it is necessary to adaptively change the criterion.

By the way, as a multiple base station cooperation method, a method in which only control information is exchanged and user data is not shared, that is, a power distribution method by Semi-Cooperation (S-Coop) is known.
The S-Coop is included in the F-Coop and has a function obtained by removing only “user data sharing” from the F-Coop. Therefore, cooperative processing by a big array is impossible, and data transmission from a plurality of BS devices to the same MS is impossible.

Hereinafter, Embodiment 4 of the present invention will be described with reference to FIGS. 14 to 17 together with FIGS.
The configuration of the radio base station apparatus to which the fourth embodiment of the present invention is applied is as shown in FIGS. However, here, since the functions are different from those of the BS devices 300 and 301 described above (FIG. 10), for the sake of convenience, “A” is appended to the reference numeral and the BS devices 300A and 301A are referred to.

FIG. 14 is an explanatory diagram of a power allocation method for parallel channels according to Embodiment 4 of the present invention, and an example of arrangement of a plurality of MSs 421 to 426 in S-Coop in association with BS apparatuses 300A and 301A (base stations). Is shown.
FIGS. 15A and 15B are explanatory diagrams illustrating a configuration example of the IEEE 802.16e DL radio frame 140, which illustrates a frame configuration of the BS device 300A and a frame configuration of the BS device 301A. FIGS. 16 (a), 16 (b), 17 (a), and 17 (b) are explanatory diagrams showing a power allocation method according to Embodiment 4 of the present invention.

In FIG. 14, MSs 421 to 423 belong to the BS apparatus 300A that supports the cell 401, and MSs 424 to 426 belong to the BS apparatus 301A that supports the cell 402.
The MSs 421 to 423 correspond to the DL bursts 451 to 453 in FIG. 15A, and the MSs 424 to 426 correspond to the DL bursts 461 to 463 in FIG.

  In this case, the MSs 421 and 424 are S-Coop target MSs, and the same subchannel is used, so that they become mutual interference sources. In general, in S-Coop, in order to reduce mutual interference, the BS apparatus 300A and the BS apparatus 301A cooperate to perform beam forming / precoding using multiple antennas.

Next, a power distribution method (power allocation 450, 460) according to Embodiment 4 of the present invention will be described with reference to FIG.
First, required powers “PT1_1_0” 474 and “PT2_1_0” satisfying desired throughput, BER, and the like for the DL Burst 451 in FIG. 16A and the DL Burst 461 in FIG. "484" is preferentially assigned over other bursts.

Subsequently, in each of the BS devices 300A and 301A, reassignment is performed according to the water injection theorem, and surplus power obtained by subtracting the priority assigned power is reassigned.
When applying the water injection theorem, the priority allocated power in each BS apparatus 300A, 301A is used as a part of the power adjustment amount, so the total power adjustment amount in DL Burst 451 is as shown in FIG. , (1 / γ1_1) + (PT1_1_0).
Also, the total power adjustment amount in DL Burst 461 is (1 / γ2_1) + (PT2_1_0) as shown in FIG.

  As a result of the power allocation by the water injection theorem in each BS apparatus 300A, 301A, for example, as shown in FIG. 16A, the water level (Water Level) 1 / η1 in the BS apparatus 300A is the DL Burst 451 subject to S-Coop. If the power adjustment amount is equal to or less than the total power adjustment amount, the result of the priority allocation power in the BS apparatus 300A and the power allocation according to the water injection theorem is the power allocation for each DL Burst in the BS apparatus 300A.

  On the other hand, as shown in FIG. 16B, as a result of the power allocation by the water injection theorem in the BS apparatus 301A, the water level 1 / η2 in one BS apparatus 301A is the total power adjustment amount of the DL Burst 461 that is the S-Coop target. When the power “PT2_1_1” 487 is assigned to the DL Burst 461, the power “PT2_2_1” 487 is not added to the power PT2_1_0, and the corresponding power is supplied to each DL Burst 462 and 463. Distribute evenly.

  Moreover, as shown in FIGS. 17A and 17B, as a result of power allocation 500 and 510 according to the water injection theorem in each BS apparatus 300A and 301A, the water level in each BS apparatus 300A and 301A is an S-Coop target. Is equal to or greater than the sum of the DL Burst 451 power adjustment amounts, and is equal to or greater than the DL Burst 461 power adjustment amount, the power “PT1_1_1” 507 is assigned to the DL Burst 451, and the power “PT2_1_1” 517 is assigned to the DL Burst 461 In such a case, additional power adjustment is performed on each DL Burst 451 and 461 to be subjected to S-Coop.

  At this time, if the ratio of the power “PT1_1_1” 507 to the power “PT1_1_0” 504 is “A1” and the ratio of the power “PT2_1_1” 517 to the power “PT2_1_1” 514 is “A2”, the high ratio DL Burst is the low ratio. In order to match the DL burst, the high ratio DL burst allocation power according to the water injection theorem is reduced, and this reduction is allocated equally to the other DL bursts.

  Specifically, when the ratio A2 is higher than the ratio A1, the power “(PT2_1_1) − (PT_2_0) × (A1)” is equally reassigned to each DL Burst 462 and 463.

As described above, according to the power allocation method (FIGS. 10, 11, and 14 to 17) for the parallel channel according to the fourth embodiment of the present invention, there are a plurality of transmitting stations and receiving stations, The transmitting stations (BS devices 300A and 301A) perform data transmission in a coordinated manner, and separate transmitting stations (MS421 and 424) out of a plurality of receiving stations (MS421 to 426) from different transmitting stations among the plurality of transmitting stations. ) And data transmission method is adjusted with other transmitting stations for transmission.
Thereby, also in S-Coop, there exists an effect equivalent to the above-mentioned.

In addition, although a plurality of MSs 421 and 424 are spatially multiplexed in the DL Burst subject to S-Coop, depending on the transmission path state and the precoding method, the interference component due to multiplexing may become dominant with respect to noise. Increasing the quota has little effect.
For example, when the required CINR is not satisfied at the time of power allocation for all DL bursts targeted for S-Coop, priority burst allocation is not performed, and DL bursts targeted for S-Coop are handled in the same manner as other DL bursts. .

  In this case, the power adjustment cancellation determination regarding the presence / absence (execution / cancellation) of priority power allocation is not limited to the above-mentioned criteria, and is based on the QoS information of DL Burst and other DL Burst QoS information of the S-Coup target. It is necessary to change the judgment criteria adaptively.

It is a block diagram which shows the radio base station apparatus with which the power allocation method with respect to the parallel channel which concerns on Embodiment 1 of this invention is applied. It is a block diagram which shows the scheduling part in FIG. 1 in detail. It is explanatory drawing which shows the structural example of the DL radio frame which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows step 1 by Embodiment 1 of this invention. It is explanatory drawing which shows step 2 by Embodiment 1 of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the receiving station in Embodiment 1 of this invention. It is explanatory drawing which shows step 1 by Embodiment 2 of this invention. It is explanatory drawing which shows step 2 by Embodiment 2 of this invention. It is explanatory drawing which shows step 2 by Embodiment 2 of this invention. It is a block diagram which shows the radio base station apparatus with which the power allocation method with respect to the parallel channel which concerns on Embodiment 3 of this invention is applied. It is explanatory drawing which shows the structural example of DL radio frame which concerns on Embodiment 3 of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the receiving station in Embodiment 3 of this invention. It is explanatory drawing which shows the power allocation method with respect to the parallel channel which concerns on Embodiment 3 of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the receiving station in Embodiment 4 of this invention. It is explanatory drawing which shows the structural example of the DL radio frame which concerns on Embodiment 4 of this invention. It is explanatory drawing which shows the power allocation method with respect to the parallel channel which concerns on Embodiment 4 of this invention. It is explanatory drawing which shows the power allocation method with respect to the parallel channel which concerns on Embodiment 4 of this invention.

Explanation of symbols

  100, 300, 300A, 301, 301A BS device (transmitting station), 103 scheduling unit, 113 cooperative operation control signal, 115 channel state measuring unit, 116 cooperative operation control unit, 160 minimum transmission rate guaranteed power allocation (step 1), 170 Surplus power reallocation (step 2), 181 to 183, 351 to 355, 421 to 426 MS (receiving station), 351 MS for F-Coop, 421, 424 MS for S-Coop, 230 Priority power allocation ( Step 1), 240, 250 Surplus power reallocation (Step 2), 380, 381, 450, 460, 500, 510 Power allocation.

Claims (4)

A power allocation method for controlling transmission power of a plurality of parallel channels in which data transmission is performed between a transmitting station and a receiving station,
Assigning a minimum power requirement for each parallel channel to all of the plurality of parallel channels;
A surplus power after the minimum required power is allocated is further allocated to all of the plurality of parallel channels according to a water injection theorem. A power allocation method for controlling transmission power of a plurality of parallel channels in which data transmission is performed between a transmitting station and a receiving station,
Assigning the required power to a priority channel of the plurality of parallel channels,
A surplus power after the required power is allocated is further allocated to all parallel channels including the priority channel according to the water injection theorem. There are a plurality of the transmitting stations and the receiving stations,
The plurality of transmitting stations perform data transmission in a coordinated manner, and transmit coordinated data from the plurality of transmitting stations to the same receiving station among the plurality of receiving stations. Item 3. A power allocation method for parallel channels according to Item 2. There are a plurality of the transmitting stations and the receiving stations,
The plurality of transmitting stations perform data transmission in a coordinated manner, and transmit data from different transmitting stations of the plurality of transmitting stations to different receiving stations of the plurality of receiving stations. 3. The method for allocating power to parallel channels according to claim 1 or 2, wherein the method is transmitted after adjusting with other transmitting stations.

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