JP2018148299A - Radio communications system and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communications system and a radio communication method capable of improving impartiality of allocation processing between desired users, reducing interference due to a pilot signal from another cell that the desired users have, and improving estimation precision of propagation path information.SOLUTION: The present invention relates to a radio communications system having a plurality of base stations arranged at a plurality of cells respectively and performing radio communication with a plurality of user terminals in the respective cells, and a base station comprises: gathering means for gathering position information on a plurality of user terminals in the cell where it is arranged and position information on a plurality of user terminals in the other cell sharing a pilot signal to be used for estimate propagation path information representing a state of a propagation path; and allocation means for allocating user terminals of the other cell to each of the plurality of user terminals in the cell thereof based upon the acquired position information such that a first index value indicative of the degree of interference with a pilot signal from the other cell.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication system and a wireless communication method.

  In recent years, wireless base stations and mobile communication terminals such as smartphones and tablet terminals are increasing due to various factors such as convenience, miniaturization, and the spread of mobile applications. Along with this, high-efficiency utilization of limited radio wave resources is required.

  As a new multi-access technology that allows multiple mobile communication terminals (hereinafter also referred to as “user terminals”) to communicate simultaneously, multi-user MIMO (Multiuser MIMO (Multiple Input Multiple Output)) with multiple antennas on the base station side Techniques have been proposed (for example, see Non-Patent Documents 1 and 2).

  In addition, in spatial multi-access technology with the introduction of multiple antennas, instead of dividing radio resources used by multiple user terminals along the frequency axis and time axis, each base station can use the entire radio resources, Base stations and user terminals realize simultaneous communication of a plurality of user terminals through transmission weights and reception weights. In particular, a technology for large-scale multi-user MIMO (Massive MIMO) with a large number of antenna elements on the base station side, which can connect more user terminals and achieve higher communication capacity than conventional MIMO technology, has been proposed. (For example, see Non-Patent Documents 3 and 4).

  In order to realize communication with a large number of user terminals by the MIMO technology, it is indispensable to calculate an accurate transmission weight based on highly accurate propagation path information. However, it is not easy to acquire highly accurate propagation path information in a mobile communication environment. In particular, in the large-scale multi-user MIMO technique, since propagation path information increases in proportion to the number of antennas and the number of users, it is more difficult to acquire propagation path information. There are two types of acquisition of propagation path information: an FDD (Frequency Division Duplex) method that feeds back estimated information to a base station and a TDD (Time Division Duplex) method that transmits a pilot signal to the base station and estimates it directly. In the case of the FDD scheme, a large-scale multi-user MIMO technique requires feedback of enormous channel information proportional to the number of antennas of the base station. For this reason, in the FDD scheme, it takes time to acquire propagation path information, compared to the TDD scheme that does not require feedback.

  On the other hand, when acquiring propagation path information by the TDD scheme, the user terminal of each cell transmits a pilot signal (or training signal) including information known in advance to the base station in the cell where the user terminal is located. It transmits to the base station of a certain own cell. The base station estimates and acquires the propagation path information using the received pilot signal. Note that the number of pilot signals is limited from the viewpoint of giving priority to transmission efficiency within a coherence period of a short radio propagation path, that is, a period with little fluctuation. Therefore, in a large-scale multi-user MIMO wireless communication system having a large number of user terminals, neighboring cells that use the same frequency must share the same set of pilot signals. As a result, interference of pilot signals between cells using the same frequency, that is, pilot contamination occurs, which causes degradation of the estimation accuracy of propagation path information in the base station, and ultimately causes a decrease in communication quality and transmission capacity. (For example, see Non-Patent Document 5).

  As a countermeasure against pilot pollution, a technique for reducing pilot pollution by assigning interfering users from other cells sharing a pilot signal using a covariance matrix of a channel response matrix has been proposed (for example, non-patent document). 6). In addition, a technique has been proposed in which interference users are allocated by using information on angle of arrival (AoA) to reduce interference due to a shared pilot signal from another cell (shared pilot) (for example, Non-patent document 7).

Quentin H. Spencer, A. Lee Swindlehurst, and Martin Haardt, “Zero-Forcing Methods for Downlink Spatial Multiplexing in Multiuser MIMO Channels,” IEEE Trans. On Signal Processing, vol. 52, no. 2, pp. 461-471, February 2004. David Gesbert, Marios Kountouris, Robert W. Heath Jr., Chan-Byoung Chae, and Thomas Salzer, “Shifting the MIMO Paradigm,” IEEE Signal Processing Magazine, vol. 24, no. 5, pp. 36-46, September 2007 . F. Rusek, D. Persson, BK Lau, EG Larsson, TL Marzetta, O. Edfors, and F. Tufvesson, “Scaling up MIMO: Opportunities and challenges with very large arrays,” IEEE Sig. Proc. Mag., Vol. 30, no. 1, pp. 40-60, Jan. 2013. E. G. Larsson, O. Edfors, F. Tufvesson, and T. L. Marzetta, “Massive MIMO for next generation wireless systems,” IEEE Comm. Mag., Vol. 52, no. 2, pp. 186-195, Feb. 2014. Jubin Jose, Alexei Ashikhminl, Thomas L. Marzettal, and Sriram Vishwanath, “Pilot Contamination Problem in Multi-Cell TDD Systems”, IEEE ISIT 2009, Seoul, Korea, June 28-July 3, 2009. Haifan Yin, David Gesbert, Miltiades Filippou, and Yingzhuang Liu, “A Coordinated Approach to Channel Estimation in Large-Scale Multiple-Antenna Systems,” IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 31, NO. 2, FEBRUARY 2013, pp 264-273. L. Srikar Muppirisetty, Henk Wymeersch, Johnny Karout, and Gabor Fodor, “Location-Aided Pilot Contamination Elimination for Massive MIMO Systems,” IEEE Global Communications Conference (GLOBECOM), 6-10 Dec. 2015.

  However, the technique of Non-Patent Document 6 is difficult in practical use because the size of the covariance matrix is proportional to the power of the number of antennas and depends on the time variation of the propagation path.

  In the technique of Non-Patent Document 7, a desired user who is a user terminal of the own cell sequentially executes interference user assignment processing. For this reason, the desired user whose allocation process is executed first has a larger number of interference user candidates that can be selected, and the desired user whose assignment process is executed later has a smaller number of candidate interference users that can be selected. That is, in Non-Patent Document 7, unfairness of allocation occurs according to the order in which the allocation processing is performed, the amount of interference due to the shared pilot received by each desired user varies, and the estimation accuracy of propagation path information between the desired users varies. There will be a disparity.

  The present invention provides a radio communication system and a radio that can improve fairness among desired users in allocation processing, reduce interference caused by pilot signals from other cells received by the desired users, and improve estimation accuracy of propagation path information An object is to provide a communication method.

  1st invention is a radio | wireless communications system which has the some base station which is arrange | positioned at each of several cell, and performs radio | wireless communication with the some user terminal in each arranged cell, Comprising: A base station is arrange | positioned Position of each of a plurality of user terminals in another cell sharing the pilot information used for estimating the position information of each of a plurality of user terminals in the own cell which is a cell and the propagation path information indicating the state of the propagation path The collecting position for collecting information and the acquired position so that the first index value indicating the degree of interference with pilot signals from other cells is minimized for each of a plurality of user terminals in the own cell. And allocating means for allocating user terminals of other cells based on the information.

  According to a second invention, in the first invention, a second index value indicating a degree of influence of interference by a pilot signal from another cell in each of a plurality of user terminals in the own cell is calculated based on position information. And determining means for determining the order in which the processing by the assigning means for each of the plurality of user terminals in the own cell is executed according to the calculated second index value, the assigning means in the determined order A feature is that user terminals in other cells are allocated to each of a plurality of user terminals in the own cell based on the position information so that the first index value is minimized.

  According to a third invention, in the first invention or the second invention, the assigning means uses location information including information indicating an angle of arrival of electromagnetic waves coming from the user terminal together with the location of the user terminal. It is characterized in that user terminals of other cells are assigned to each of the plurality of user terminals so that the first index value combining the arrival angle and the distance attenuation is minimized.

  In a fourth aspect based on the second aspect, the determining means uses position information of each of the plurality of user terminals in the own cell including information indicating an arrival angle of an electromagnetic wave coming from the user terminal together with the position of the user terminal. Thus, the second index value combining the arrival angle and the distance attenuation is calculated for each of the plurality of user terminals in the own cell.

  A fifth invention is a radio communication method of a radio communication system that is arranged in each of a plurality of cells and has a plurality of base stations that perform radio communication with a plurality of user terminals in each of the arranged cells. Collects location information of multiple user terminals in its own cell, and location information of multiple user terminals in other cells that share a pilot signal used to estimate propagation path information indicating the state of the propagation path Then, for each of the plurality of user terminals in the own cell, the other cell based on the acquired location information is set so that the first index value indicating the degree of interference with the pilot signal from the other cell is minimized. The user terminal is assigned.

  According to a sixth aspect based on the fifth aspect, the second index value indicating the degree of influence of interference due to pilot signals from other cells in each of the plurality of user terminals in the own cell is calculated based on the position information. Then, in accordance with the calculated second index value, the order in which the process of assigning user terminals of other cells to each of the plurality of user terminals in the own cell is determined, and the process of assigning user terminals of other cells Is characterized in that user terminals in other cells are allocated to each of a plurality of user terminals in the own cell in the determined order so that the first index value is minimized.

  In a seventh aspect based on the fifth aspect or the sixth aspect, the process of assigning user terminals of other cells includes position information including information indicating an arrival angle of electromagnetic waves arriving from the user terminal together with the position of the user terminal. And assigning user terminals in other cells to each of a plurality of user terminals in the own cell so that the first index value combining the arrival angle and the distance attenuation is minimized. .

  In an eighth aspect based on the sixth aspect, the processing for determining the order includes the position of each of a plurality of user terminals in the own cell including information indicating an arrival angle of an electromagnetic wave coming from the user terminal together with the position of the user terminal. Using the information, a second index value that combines the angle of arrival and the distance attenuation is calculated for each of a plurality of user terminals in the own cell.

  The present invention can improve fairness among desired users in allocation processing, reduce interference caused by pilot signals from other cells received by the desired users, and improve estimation accuracy of propagation path information.

1 is a diagram illustrating an embodiment of a wireless communication system. It is a figure which shows an example of the allocation process in the base station shown in FIG. It is a figure which shows an example of description of the index value M. It is a figure which shows another example of the allocation process in the base station shown in FIG. It is a figure which shows an example in case the spread of the arrival angle in a desired user is made into an index value. It is a figure which shows the average normalization estimation error of all the users in an own cell. It is a figure which shows the normalization estimation error of each user.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a wireless communication system.

  The radio communication system SYS illustrated in FIG. 1 is, for example, a large-scale multiuser MIMO system. The radio communication system SYS includes a base station BS (BS (1) -BS (7)) arranged in each of seven cells C (C1-C7), and two user terminals UT (UT11, UT12) in each cell C. UT21, UT22, UT31, UT33, UT41, UT42, UT51, UT52, UT61, UT62, UT71, UT72). Note that the radio communication system SYS may have a plurality of base stations BS other than 7. Further, the radio communication system SYS may have a plurality of user terminals UT other than 2 in each cell C.

  The user terminal UT is a mobile communication terminal such as a smartphone or a tablet-type terminal, and performs wireless communication with a base station BS of a cell C (own cell) where the user terminal UT is located.

  The base station BS is, for example, an access point or a cellular base station. The base station BS performs radio communication with each of the user terminals UT of the arranged cell C (own cell) via a plurality of antennas included in the base station BS.

  In addition, the base station BS shares a set of a plurality of pilot signals orthogonal to each other with the base station BS of another cell C. The base station BS sets one of the pilot signals for each user terminal UT in its own cell. Then, the user terminal UT transmits the set pilot signal to the base station BS of the own cell in the TDD scheme, and the base station BS uses the received pilot signal to propagate with the user terminal UT of the own cell. The propagation path information indicating the path state is estimated.

  However, since the set of pilot signals is shared by each of the cells C1 to C7, for example, the base station BS (1), as shown in FIG. 1, receives the pilot signal s1 indicated by the solid line from the user terminal UT11 of the own cell C1. And a pilot signal s1 indicated by a broken line is received from the user terminal UT21 of the cell C2. Similarly, the base station BS (1) receives a pilot signal s2 indicated by a solid line from the user terminal UT12 of its own cell C1, and also receives a pilot signal s2 indicated by a broken line from the user terminal UT72 of the cell C7.

  Thereby, in base station BS (1), pilot signal s1 from user terminal UT11 and pilot signal s1 from user terminal UT21 interfere with each other. The interference of the pilot signal is pilot contamination, and it becomes difficult for the base station BS (1) to estimate the propagation path information with the user terminal UT11 of the own cell C1. Similarly, the base station BS (1) can estimate the propagation path information between the user terminal UT12 of the own cell C1 due to interference between the pilot signal s2 from the user terminal UT12 and the pilot signal s2 from the user terminal UT72. It becomes difficult. Therefore, the base station BS executes pilot signal allocation processing shown in FIG. 2 in order to reduce pilot contamination.

  FIG. 2 shows an example of allocation processing in the base station BS (1) shown in FIG. In the processing shown in FIG. 2, the number of cells C1 (own cell) in which the base station BS (1) is arranged and another cell C sharing the pilot signal is L (= 7). Further, it is assumed that each cell C has K (= 2) user terminals UT.

  2 is realized by an arithmetic processing device such as a processor included in the base station BS (1) executing a program stored in a storage device such as a hard disk device. That is, the process illustrated in FIG. 2 is an embodiment of a wireless communication method. The program may be stored and distributed in a storage medium that can be read by the arithmetic processing device, or may be distributed via a network. The base stations BS (2) -BS (7) execute the same or similar processing as the base station BS (1).

  In step S100, the base station BS (1) collects location information of the user terminal UT of the own cell C1 from each of the user terminals UT of the own cell C1. Further, the base station BS (1) collects location information of the user terminals UT of other cells C from the user terminals UT of other cells C, respectively.

  Next, in step S110, the base station BS (1) assigns pilot signals to be used individually to desired users, which are K user terminals UT of the own cell C1.

  Next, in step S120, the base station BS (1) receives pilots from other cells C received by each desired user sequentially from the K user terminals UT11 of the own cell C1 to the desired users of the user terminal UT1K. Based on the location information, an interfering user who is a user terminal UT in another cell C is assigned so that signal interference is minimized.

  For example, the base station BS (1) calculates an index value (metric) M used for interference user allocation using the position information acquired in step S100 and the expressions (1) and (2).

  FIG. 3 shows an example of the explanation of the index value M. In FIG. 3, the position of the base station BS (1) is taken as the coordinate origin, and among the K desired users in the own cell C1, the i-th user terminal UT1i and another cell Cj (hereinafter “other cell j”) M-th user terminal UTjm). Note that j is an integer from 2 to L, and m is an integer from 1 to K.

  As shown in FIG. 3, θmin (i) and θmax (i) indicate the minimum arrival angle and the maximum arrival angle of the electromagnetic wave arriving from the user terminal U1i of the own cell C1. θmin (j, m) and θmax (j, m) indicate the minimum arrival angle and the maximum arrival angle of the electromagnetic wave arriving from the user terminal Ujm of another cell j. Information indicating each angle of arrival is included in the position information acquired in step S100.

  The base station BS (1) assigns an interference user whose index value M is the largest among the K interference users of the other cell j with little overlap with the arrival angle with the desired user of the own cell C1. That is, the base station BS (1) allocates only one interfering user who shares a pilot signal with a desired user of the own cell C1 from each other cell j.

  Note that the base station BS (1) may obtain the index value M using Equation (3) that combines the arrival angle and the distance attenuation together with Equation (2).

Here, _{x B} represents the XY coordinates of the position of the base station BS _{(1), x jm} indicates the XY coordinates of the position of the user terminal UTjm a m th interference user of another cell j. γ is a variable parameter in the system design of the wireless communication system SYS.

  The base station BS (1) shares the pilot signal in consideration of both the overlapping of arrival angles of individual interfering users in the other cell j and the desired user terminal station and the distance attenuation with the base station BS (1). Assigning interfering users. For example, the base station BS (1) preferentially assigns interfering users whose distance from the base station BS (1) is far (distance attenuation is large) when the arrival angles overlap or the overlapping ratio is large. On the other hand, the base station BS (1) preferentially assigns interfering users whose distance from the base station BS (1) is short (distance attenuation is small) when the arrival angles do not overlap or the overlapping ratio is small.

  That is, the base station BS (1) expands the index value M from the one-dimensional information of only the arrival angle to the two-dimensional information of the arrival angle and the distance attenuation, thereby making the fairness among the desired users more Can keep.

  In step S130, the base station BS (1) determines whether or not all the interference users of other cells j have been allocated. When all the interference users of the other cell j are assigned, the process of the base station BS (1) moves to step S140. On the other hand, when the interference user of all the other cells j is not allocated, the process of base station BS (1) moves to step S120.

  In step S140, the base station BS (1) determines whether there is a next desired user. If there is a next desired user, the process of the base station BS (1) moves to step S120. On the other hand, if there is no next desired user, the base station BS (1) ends the allocation process.

  In addition, the process of step S120 and step S130 may be loop-processed as shown in FIG. 2, and may be processed in parallel for every other cell j.

  In the embodiment shown in FIG. 1 to FIG. 3, the base station BS (1) causes the interference of pilot signals from other cells j received by each desired user sequentially to K desired users of its own cell C1. Based on the location information, interfering users in other cells j are allocated so as to be minimized. That is, the base station BS (1) has little overlap with the arrival angle with the desired user of the own cell C1 among the K interference users of the other cell j, and the index value of Expression (1) or Expression (3) Interfering users are assigned such that M is maximized. Thereby, the radio communication system SYS can improve the fairness among the desired users in the allocation process, reduce interference caused by pilot signals from other cells received by the desired users, and improve the estimation accuracy of the propagation path information. .

  FIG. 4 shows another example of allocation processing in the base station BS (1) shown in FIG. Note that among the processes of the steps shown in FIG. 4, those showing the same or similar processes as the steps shown in FIG. 2 are given the same step numbers. In the processing shown in FIG. 4, as in FIG. 2, the number of cells between the cell C1 (own cell) in which the base station BS (1) is arranged and the other cell C sharing the pilot signal is , L (= 7). Further, it is assumed that each cell C has K (= 2) user terminals UT.

  Further, the processing shown in FIG. 4 is realized by the arithmetic processing device of the base station BS (1) executing a program stored in the storage device. That is, the process shown in FIG. 4 is another embodiment of the wireless communication method. Note that the base stations BS (2) -BS (7) execute the same or similar processing as the base station BS (1).

  After executing the process of step S100, the base station BS (1) executes the process of step S110 and the process of step S115 in parallel.

  In step S115, the base station BS (1) assigns interference users in other cells in the order of desired users that are easily affected by interference of pilot signals from other cells, based on the position information acquired in step S100. Is determined for each of the K desired users of its own cell C1.

  For example, when determining the order, the base station BS (1) calculates an index value (metric) indicating the ease of being affected by the interference of pilot signals from other cells.

  FIG. 5 shows an example in which the spread of the arrival angle of the desired user is used as an index value. FIG. 5 shows the user terminal UT11 and the user terminal UT1K among the K desired users in the own cell C1 with the position of the base station BS (1) as the coordinate origin.

As illustrated in FIG. 5, the base station BS (1), for example, includes the maximum arrival angle θmax (i of electromagnetic waves arriving from the user terminal UT1i included in the position information of the user terminal UT1i of the own cell collected in step S100. ) And the minimum angle of arrival θmin (i), the arrival angle spread Δθi is obtained. Note that i is an integer from 1 to K.
Δθi = θmax (i) −θmin (i) (4)
Then, the base station BS (1), for example, is more susceptible to interference with pilot signals from other cells as the desired user with a wider arrival angle spread Δθ, and pilots from other cells as the desired user with a smaller arrival angle spread Δθ. The order of the desired users to execute the interference user assignment process is determined on the assumption that it is difficult to receive signal interference. That is, when the obtained arrival angle spread Δθ is Δθ1 ≧ Δθ2 ≧. To the last desired user.

Note that the base station BS (1) may obtain an arrival angle spread Δθ combining the maximum arrival angle θmax, the minimum arrival angle θmin, and the distance attenuation as an index value using the equation (5).
Δθi = (θmax (i) −θmin (i)) / || x _B −x _i || ^γ (5)
Here, _{x B} represents the XY coordinates of the position of the base station BS (1), _{x i} represents the XY coordinates of the position of the user terminal UT1i the desired users own cell C1. γ is a variable parameter in the system design of the wireless communication system SYS.

  As a result, the base station BS (1) considers both the spread of the arrival angle of each desired user in the own cell C1 and the distance attenuation with the base station BS (1) as compared with the case where the equation (4) is used. Thus, the order of executing the allocation process can be determined.

  And base station BS (1) performs the process of step S125, after performing the parallel process of step S110 and step S115.

  In step S125, the base station BS (1) sequentially receives from each other cell C received by each desired user of its own cell C1 according to the order determined in step S115, similarly to the process of step S120 shown in FIG. Based on the location information, an interfering user who is a user terminal UT in another cell C is assigned so that the interference of the pilot signal is minimized.

  After the process of step S125, the base station BS (1) executes the processes of step S130 and step S140, and ends the allocation process.

  In addition, the process of step S125 and step S130 may be loop-processed as shown in FIG. 4, and may be processed in parallel for every other cell j.

  In the embodiment shown in FIG. 4 and FIG. 5, the base station BS (1), based on the acquired location information, in the order of the desired users that are susceptible to the interference of pilot signals from the other cell j. The order for each of the K desired users of the own cell C1 is determined so that the allocation process of j interference users is executed. Thereby, the radio | wireless communications system SYS can improve the fairness between the desired users in an allocation process.

  In addition, the base station BS (1), for the K desired users of the own cell C1, sequentially minimizes the interference of pilot signals from other cells j received by each desired user according to the determined order. Based on the location information, an interfering user in another cell j is assigned. That is, the base station BS (1) has little overlap with the arrival angle with the desired user of the own cell C1 among the K interference users of the other cell j, and the index value of Expression (1) or Expression (3) Interfering users are assigned such that M is maximized. Thereby, the radio communication system SYS can improve the fairness among the desired users in the allocation process, reduce interference caused by pilot signals from other cells received by the desired users, and improve the estimation accuracy of the propagation path information. .

  6 and 7 show the results of quantitative evaluation of the wireless communication system SYS shown in FIG. 1 by simulation. That is, FIG. 6 shows the average normalized estimation error of all users in the own cell, and FIG. 7 shows the normalized estimation error of each user. Note that the horizontal axis of FIG. 6 indicates the number of antennas included in the base station BS, and the vertical axis indicates the normalized estimation error MSE. In addition, the horizontal axis of FIG. 7 indicates the user index, and the vertical axis indicates the normalized estimation error MSE of the propagation path information of each corresponding user.

  Table 1 shows the specifications of the simulation for evaluating the present invention. As shown in Table 1, the number of antennas provided in the base station BS of each cell C is 50, and the number of active user terminals UT of each cell C is 10.

  6 and 7, together with the interference user allocation (Proposed) of the present invention shown in FIG. 2, the pilot allocation (AoA based) based on the conventional arrival angle (AoA) and the interference user allocation based on only the estimated distance information (Distance based). ) And random interference user assignment (Random) results. 6 and 7 show quantitative characteristics (Interference free scenario) in an ideal case without inter-cell interference.

  As shown in FIG. 6, the present invention suppresses the estimation error of the total propagation path information as compared with the conventional technique. In addition, the tendency increases with the number of antennas provided in the base station BS.

  Also, as shown in FIG. 7, the present invention significantly reduces the difference in estimation accuracy between users compared to the prior art. That is, as a result of the interference user allocation sharing the pilot signal according to the present invention, fairness among the desired users is maintained.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

C1-C7 ... cell; BS (1)-BS (7) ... base station; s1, s2 ... pilot signal; SYS ... wireless communication system; UT11, UT12, UT21, UT22, UT31, UT33, UT41, UT42, UT51, UT52, UT61, UT62, UT71, UT72 ... User terminal

Claims (8)

A wireless communication system having a plurality of base stations arranged in each of a plurality of cells and performing wireless communication with a plurality of user terminals in each of the arranged cells,
The base station
The plurality of users of other cells sharing the position information of each of the plurality of user terminals in the own cell, which is the arranged cell, and the pilot signal used for estimating the propagation path information indicating the state of the propagation path A collecting means for collecting location information of each terminal;
Based on the acquired position information so that the first index value indicating the degree of interference with the pilot signal from the other cell is minimized for each of the plurality of user terminals in the own cell. An allocating means for allocating the user terminal of the other cell. The wireless communication system according to claim 1, wherein
A second index value indicating a degree of influence of interference by the pilot signal from the other cell in each of the plurality of user terminals in the own cell is calculated based on the position information, and the calculated second According to an index value, further comprising a determining means for determining the order in which the processing by the allocating means is performed for each of the plurality of user terminals in the own cell;
The allocating unit is configured to determine the first index value for each of the plurality of user terminals in the own cell in the determined order so that the first index value is minimized based on the location information. A wireless communication system, characterized by allocating user terminals. The wireless communication system according to claim 1 or 2,
The allocating means uses the position information including information indicating an angle of arrival of an electromagnetic wave coming from the user terminal together with the position of the user terminal, for each of the plurality of user terminals in the own cell. The wireless communication system, wherein the user terminals of the other cells are allocated so that the first index value combining the corner and the distance attenuation is minimized. The wireless communication system according to claim 2,
The determining means uses the position information of each of the plurality of user terminals in the own cell including information indicating an arrival angle of an electromagnetic wave coming from the user terminal together with a position of the user terminal, and The wireless communication system, wherein the second index value combined with distance attenuation is calculated for each of the plurality of user terminals in the own cell. A wireless communication method of a wireless communication system having a plurality of base stations arranged in each of a plurality of cells and performing wireless communication with a plurality of user terminals in each of the arranged cells,
The location information of the plurality of user terminals in the own cell which is the arranged cell and the plurality of user terminals of other cells sharing a pilot signal used for estimation of propagation path information indicating the state of the propagation path Collect location information and
Based on the acquired position information so that the first index value indicating the degree of interference with the pilot signal from the other cell is minimized for each of the plurality of user terminals in the own cell. The wireless communication method, wherein the user terminal of the other cell is allocated. The wireless communication method according to claim 5, wherein
A second index value indicating a degree of influence of interference by the pilot signal from the other cell in each of the plurality of user terminals in the own cell is calculated based on the position information, and the calculated second According to the index value, determine the order in which the process of assigning the user terminal of the other cell to each of the plurality of user terminals in the own cell is executed,
The process of assigning the user terminals of the other cells is performed on the location information so that the first index value is minimized for each of the plurality of user terminals in the own cell in the determined order. A wireless communication method characterized by allocating the user terminal in the other cell based on the method. The wireless communication method according to claim 5 or 6,
The process of assigning the user terminal of the other cell uses the position information including information indicating an arrival angle of an electromagnetic wave coming from the user terminal together with the position of the user terminal, and the plurality of the plurality of terminals in the own cell. The wireless communication method, wherein the user terminal of the other cell is assigned to each of the user terminals so that the first index value combining the angle of arrival and the distance attenuation is minimized. The wireless communication method according to claim 6,
The process of determining the order uses the position information of each of the plurality of user terminals in the own cell including information indicating an arrival angle of an electromagnetic wave coming from the user terminal together with the position of the user terminal, The wireless communication method, wherein the second index value combining the arrival angle and the distance attenuation is calculated for each of the plurality of user terminals in the own cell.