Method for determining position of user equipment and apparatus for performing same in wireless mobile communication system

Abstract

The present invention relates to a method for determining position of a user equipment in a wireless mobile communication system. The method comprises receiving a plurality of subframes including reference signals for positioning of the user equipment from a plurality of base stations periodically with a predetermined period of time; and determining position of the user equipment using reference signal time difference (RSTD) between the reference signals for positioning of the user equipment included in the received plurality of subframes, wherein a pattern of the reference signals for positioning of the user equipment is generated by repeating a diagonal mother matrix with dimension of 66, the pattern of the reference signals are mapped to orthogonal frequency division multiplexing (OFDM) symbols of the subframe, and the reference signals for positioning of the user equipment in a OFDM symbol in which common reference signal (CRS) is transmitted are punctured.

Claims

1. A method for determining position of a user equipment in a wireless mobile communication system, the method comprising: receiving positioning reference signals in a plurality of subframes; and measuring reference signal time difference (RSTD) between the positioning reference signals received in the plurality of subframes used for determining a position of the user equipment, wherein a pattern of the positioning reference signals corresponds to a 1212 resource element matrix pattern, the pattern of the positioning reference signals is mapped to 1212 resource elements specified by 12 subcarriers and 12 orthogonal frequency division multiplexing (OFDM) symbols of each of the subframes, and the positioning reference signals are not transmitted on 12 subcarriers in a OFDM symbol in which a common reference signal (CRS) is transmitted, and wherein at least 3 OFDM symbols from an initial OFDM symbol are not used for the positioning reference signals in each of the subframes regardless of a number of OFDM symbols used for a physical downlink control channel.

2. The method of claim 1, wherein a 66 diagonal resource element matrix pattern is repeated 4 times in the 1212 resource element matrix pattern.

3. The method of claim 1, wherein if the subframes have a normal cyclic prefix, OFDM symbol indexes 3 and higher are used for the pattern of the positioning reference signals.

4. The method of claim 1, wherein if the subframes have an extended cyclic prefix, OFDM symbol indexes 4 and higher are used for the pattern of the positioning reference signals.

5. A user equipment in a wireless mobile communication system, comprising: a receiver; and a processor, wherein the receiver is configured to receive positioning reference signals in a plurality of subframes, wherein the processor is configured to measure measuring reference signal time difference (RSTD) between the positioning reference signals received in the plurality of subframes used for determining a position of the user equipment, wherein a pattern of the positioning reference signals corresponds to a 1212 resource element matrix pattern, the pattern of the positioning reference signals is mapped to 1212 resource elements specified by 12 subcarriers and 12 orthogonal frequency division multiplexing (OFDM) symbols of each of the subframes, and the positioning reference signals are not transmitted on 12 subcarriers in a OFDM symbol in which a common reference signal (CRS) is transmitted, and wherein at least 3 OFDM symbols from an initial OFDM symbol are not used for the positioning reference signals in a subframe regardless of a number of OFDM symbols used for a physical downlink control channel.

6. The user equipment according to claim 5, wherein a 66 diagonal resource element matrix pattern is repeated 4 times in the 1212 resource element matrix pattern.

7. The user equipment according to claim 5, wherein if the subframes have a normal cyclic prefix, OFDM symbol indexes 3 and higher are used for the pattern of the positioning reference signals.

8. The user equipment according to claim 5, wherein if the subframes have an extended cyclic prefix, OFDM symbol indexes 4 and higher are used for the pattern of the positioning reference signals.

9. The method of claim 1, wherein a frequency-shift is applied to the pattern of the positioning reference signals for each cell, and wherein the frequency-shift is determined based on NcellID mod 6, where NcellID is a cell identifier, and mod denotes modular operation.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows the structure of a type 1 radio frame;

(2) FIG. 2 shows the structure of a type 2 radio frame;

(3) FIG. 3 shows the structure of a LTE downlink slot;

(4) FIG. 4 shows the structure of a LTE uplink slot;

(5) FIG. 5 shows the structure of a downlink subframe;

(6) FIG. 6 shows a configuration of a conventional MIMO communication system;

(7) FIG. 7 shows the structure of a UE (User Equipment)-specific reference signal in a subframe using a normal CP (Cyclic Prefix), in which one TTI (Transmission Time Interval) has 14 OFDM symbols;

(8) FIG. 8 shows the structure of a UE-specific reference signal in a subframe using an extended CP, in which one TTI has 12 OFDM symbols;

(9) FIGS. 9, 10 and 11 show structures of UE-common downlink reference signals for systems respectively having one, two and four transmit antennas when one TTI has 14 OFDM symbols;

(10) FIG. 12 shows an example of downlink OTDOA that is a kind of a terrestrial positioning based method used in 3GPP standard;

(11) FIG. 13 shows an example of a user equipment positioning method using OTDOA;

(12) FIGS. 14 and 15 show structures of subframes including LCS RSs for OTDOA;

(13) FIG. 16 illustrates a state that LCS RSs are received without being synchronized from multiple cells;

(14) FIG. 17 shows a matrix pattern according to reuse planning using a Costas array when N=6;

(15) FIG. 18 shows a result of allocation of cell IDs to the Costas array pattern shown in FIG. 17;

(16) FIGS. 19 and 20 show exemplary results of circular shifting and permutation of the Costas array pattern shown in FIG. 18;

(17) FIG. 21 shows a result of allocation of cell IDs to a matrix according to reuse planning using a Costas array when N=10;

(18) FIG. 22 shows punctured columns in a cell ID/symbol modular based mother matrix with N=12 in a normal cyclic prefix (CP) case;

(19) FIG. 23 shows a case in which a cell ID/symbol modular based mother matrix with N=12 is applied to subframes;

(20) FIG. 24 shows an example of applying a mother matrix with N=12 to MBSFN subframe;

(21) FIG. 25 shows a result of circular shift of the matrix shown in FIG. 22 by 2 to the right in a normal CP case;

(22) FIG. 26 shows a result of circular shift of the matrix shown in FIG. 22 by 3 to the right in an extended CP case;

(23) FIG. 27 shows a result obtained by applying the matrix shown in FIG. 25 and the matrix shown in FIG. 26 to subframes and performing puncturing;

(24) FIG. 28 shows a result obtained by applying the matrix shown in FIG. 25 to MBSFN subframe and performing puncturing;

(25) FIG. 29 shows an example of puncturing performed with the first column of a mother matrix with N=12 located on the last CRS symbol of a subframe in a normal CP case;

(26) FIG. 30 shows an example of puncturing performed with the first column of a mother matrix having N=12 located on the last CRS symbol of a MBSFN subframe;

(27) FIG. 31 shows an example of a Costas array with N=12;

(28) FIG. 32 shows cases in which the Costas array shown in FIG. 31 is applied to subframes;

(29) FIG. 33 shows a case in which the Costas array shown in FIG. 31 is applied to MBSFN subframe;

(30) FIG. 34 shows an example of applying a Costas array based mother matrix with N=6 to a subframe and performing puncturing in a normal CP case;

(31) FIG. 35 shows an example of applying a Costas array based mother matrix with N=6 to a subframe and performing puncturing in an extended CP case;

(32) FIG. 36 shows an example of applying a Costas array based mother matrix with N=6 according to an embodiment of the present invention to a subframe and performing puncturing;

(33) FIG. 37 shows an example of applying a Costas array based mother matrix with N=6 according to an embodiment of the present invention to a subframe and performing puncturing;

(34) FIG. 38 shows an example of applying a cell ID/symbol modular based mother matrix with N=6 according to an embodiment of the present invention to a subframe and performing puncturing;

(35) FIG. 39 shows patterns extended by repeating at least one column or row of a Costas array based mother matrix according to an embodiment of the present invention;

(36) FIG. 40 shows patterns extended by repeating at least one column or row of a cell ID/symbol modular based mother matrix according to an embodiment of the present invention;

(37) FIG. 41 shows results of mirroring mapping using a Costas array according to an embodiment of the present invention;

(38) FIG. 42 shows a PRS pattern for frequency reuse 6 according to an embodiment of the present invention;

(39) FIG. 43 shows position determination performance depending on system bandwidth;

(40) FIG. 44 shows position determination performance in a time-varying PRS pattern;

(41) FIG. 45 shows position determination performance with respect to orthogonal frequency reuse 6 and orthogonal time reuse 6;

(42) FIG. 46 shows a result of comparison of performances for different PRS patterns on ideal timing assumption;

(43) FIG. 47 shows a result of comparison of performances for different PRS patterns on practical timing assumption; and

(44) FIG. 48 is a block diagram of a device capable of being applied to a base station and user equipment and performing the method of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(45) Reference will now be made in detail to the preferred embodiments of the present invention with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the invention. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details. In some instances, known structures and devices are omitted, or are shown in block diagram form focusing on important features of the structures and devices, so as not to obscure the concept of the present invention. The same reference numbers will be used throughout this specification to refer to the same or like parts.

(46) Throughout the specification, when a certain part includes a certain element, it means that the part can further include other elements not excluding the other elements. Furthermore, the terms unit and part mean units which process at least one function or operation, which can be implemented by hardware, software, or combination of hardware and software.

(47) The present invention proposes a method of extending a mother matrix representing mapping of reference signals (RSs) for user equipment position determination such that the RSs are transmitted within a predetermined section (for example, a subframe or one resource block) based on the mother matrix or mapping the RSs within the predetermined section based on the mother matrix.

(48) In particular, the present invention proposes the following RS patterns.

(49) (1) A pattern extended by changing the order of at least two columns or rows of a mother matrix

(50) (2) A pattern obtained by puncturing at least one column or row of a mother matrix

(51) This pattern includes a pattern extended by changing the order of at least two columns or rows of a mother matrix.

(52) (3) A pattern extended by repeating at least one column or row of a mother matrix

(53) This pattern includes a pattern extended by changing the order of at least two columns or rows of a mother matrix.

(54) (4) A pattern arranged such that frequency reuse of coexisting different types of RSs (for example, CRS or DRS (Dedicated Reference Signal)) corresponds to at least one column or row of a mother matrix in consideration of the existing RS or the coexisting different types of RSs

(55) In this pattern, the remaining columns and rows may be mapped in a circular shift form.

(56) (5) A pattern in which at least one column of a mother matrix is repeated around a coexisting different type of RS (for example, CRS or DRS) in consideration of the existing RS or the coexisting different type of RS

(57) The present invention supposes 1) a mother matrix based on a Costas array and 2) a mother matrix based on cell ID/symbol modular. However, the present invention is not limited to these mother matrices and can be based on various mother matrices.

(58) The mother matrix based on a Costas array and the mother matrix based on cell ID/symbol modular will now be explained.

(59) 1) Costas array based mother matrix

(60) A Costas array named after John P. Costas can be regarded geometrically as a set of n points lying on the squares of an nn checkerboard, such that each row or column contains only one point, and that all of the n(n1)/2 displacement matrices between each pair of dots are distinct. This results in an ideal thumbtack auto-ambiguity function, making the array useful in applications such as sonar and radar.

(61) A Costas array may be represented numerically as an nn array of numbers, where each entry is either 1, for a point, or 0, for the absence of a point. When interpreted as binary matrices, these arrays of numbers have the property that, since each row and column has the constraint that it only has one point on it, they are therefore also permutation matrices. Thus, the Costas arrays for any given n are a subset of the permutation matrices of order n.

(62) A Welch-Costas array, or Welch array is generated using the following method. The Welch-Costas array is constructed by taking a primitive root g of a prime number p and defining the array A by A.sub.i,j=1, otherwise 0. The result is a Costas array of size p1.

(63) For example, 3 is a primitive root of 5. Here, a Costas permutation can be obtained using the following modulo operations.
3^1=3
3^2=9=4(mod 5)
3^3=27=2(mod 5)
3^4=81=1(mod 5)

(64) Therefore, [3,4,2,1] is a Costas permutation. More specifically, this is an exponential Welch array. The transposition of the array is a logarithmic Welch array.

(65) FIG. 17 shows a matrix pattern according to reuse planning using a Costas array when N=6. That is, FIG. 17 shows a 66 Costas array pattern. FIG. 18 shows a result of allocation of cell IDs to the Costas array pattern of FIG. 17. A specific column of the Costas array shown in FIG. 18 can be circular-shifted or permutated. FIGS. 19 and 20 show exemplary results of circular shift or permutation of the Costas array shown in FIG. 18.

(66) The matrix pattern can be extended to a matrix with N=10 using the above-mentioned method. FIG. 21 shows a result of allocation of cell IDs to a matrix according to reuse planning using a Costas array when N=10.

(67) The cell ID/symbol modular based mother matrix will now be explained.

(68) 2) Cell ID/symbol modular based mother matrix

(69) The cell ID/symbol modular based mother matrix can be generated using the following Equation 4.
k.sub.n.sup.m=mod(mod(a.sup.m.Math.(n+1),N.sub.p)1+n.sub.subblock,N)
n=0,1, . . . ,N.sub.sym1
n.sub.subblock=0,1, . . . ,N.sub.subblock-1[Equation 5]

(70) In Equation 5, N.sub.sym may be the number of OFDM symbols in one subframe, and n.sub.subblock may be the number of NN matrices in a specific range. Here, if subblocks are generated based on subframes, n.sub.subblock may be a subframe index n.sub.SF. Though n.sub.SF can have the same value for all subframes, it is assumed that n.sub.SF has different values for subframes in the present invention. N.sub.p may be the smallest prime number among integers larger than N.

(71) Furthermore, a.sup.m may be a function of cell IDs.

(72) Here, the cell IDs may be reused cell IDs. For example, if the number of cell IDs is 504, cell IDs used in the present invention can be represented as m=mod(n_cellid, N) when reuse of N cell IDs is applied.

(73) Here, n.sub.subblock designates a hopping pattern depending on a specific unit and can be defined in connection with cell IDs as well as n.sub.SF. For example, n.sub.subblock can be designated as n.sub.subblock=n.sub.SF+cell ID such that a RS pattern can be hopped in connection with cell IDs for each subframe.

(74) An example of a matrix with N=6 is represented as follows.

(75) $\begin{array}{cc}\begin{array}{cccccc}0& 3& 4& 1& 2& 5\\ 1& 0& 2& 3& 5& 4\\ 2& 4& 0& 5& 1& 3\\ 3& 1& 5& 0& 4& 2\\ 4& 5& 3& 2& 0& 1\\ 5& 2& 1& 4& 3& 0\end{array}& \left[\mathrm{Expression}6\right]\end{array}$

(76) An example of a matrix with N=10 is represented as follows.

(77) $\begin{array}{cc}\begin{array}{cccccccccc}0& 5& 3& 2& 8& 1& 7& 6& 4& 9\\ 1& 0& 7& 5& 6& 3& 4& 2& 9& 8\\ 2& 6& 0& 8& 4& 5& 1& 9& 3& 7\\ 3& 1& 4& 0& 2& 7& 9& 5& 8& 6\\ 4& 7& 8& 3& 0& 9& 6& 1& 2& 5\\ 5& 2& 1& 6& 9& 0& 3& 8& 7& 4\\ 6& 8& 5& 9& 7& 2& 0& 4& 1& 3\\ 7& 3& 9& 1& 5& 4& 8& 0& 6& 2\\ 8& 9& 2& 4& 3& 6& 5& 7& 0& 1\\ 9& 4& 6& 7& 1& 8& 2& 3& 5& 0\end{array}& \left[\mathrm{Expression}7\right]\end{array}$

(78) An example of a matrix with N=12 is represented as follows.

(79) $\begin{array}{cc}\begin{array}{cc}\begin{array}{cccccccccccc}0& 6& 8& 9& 7& 10& 1& 4& 2& 3& 5& 11\\ 1& 0& 4& 6& 2& 8& 3& 9& 5& 7& 11& 10\\ 2& 7& 0& 3& 10& 6& 5& 1& 8& 11& 4& 9\\ 3& 1& 9& 0& 5& 4& 7& 6& 11& 2& 10& 8\\ 4& 8& 5& 10& 0& 2& 9& 11& 1& 6& 3& 7\\ 5& 2& 1& 7& 8& 0& 11& 3& 4& 10& 9& 6\\ 6& 9& 10& 4& 3& 11& 0& 8& 7& 1& 2& 5\\ 7& 3& 6& 1& 11& 9& 2& 0& 10& 5& 8& 4\\ 8& 10& 2& 11& 6& 7& 4& 5& 0& 9& 1& 3\\ 9& 4& 11& 8& 1& 5& 6& 10& 3& 0& 7& 2\\ 10& 11& 7& 5& 9& 3& 8& 2& 6& 4& 0& 1\\ 11& 5& 3& 2& 4& 1& 10& 7& 9& 8& 6& 0,\end{array}& \end{array}& \left[\mathrm{Expression}8\right]\end{array}$

(80) As described above in 1) Costas array based mother matrix, a mother matrix can be generated by circularly shifting or permuting the above matrices.

(81) Generation of the above-mentioned RS pattern will now be explained in detail based on the aforementioned mother matrices.

(82) (1) The pattern extended by changing the order of at least two columns or rows of a mother matrix corresponds to the above-described pattern in which the order of columns or rows is changed through circular shift or permutation. Here, although it was assumed that the control channel region corresponds to three OFDM symbols, the control channel region is not limited thereto.

(83) (2) The Pattern Obtained by Puncturing at Least One Column or Row of a Mother Matrix

(84) If a RS pattern is designed based on one resource block and one subframe, the size of a generated mother matrix may be based on a larger one of a time resource and a frequency resource. For example, one RB is composed of 12 subcarriers, one subframe includes 8 OFDM symbols in a normal CP case and 6 OFDM symbols in an extended CP case except a control region and CRS. Accordingly, a mother matrix having N=12 can be designed. In this case, gain according to reuse can be maximized.

(85) Alternatively, the size of a generated mother matrix may be based on a smaller one of the time resource and frequency resource. For example, one RB is composed of 12 subcarriers, one subframe includes 8 OFDM symbols in a normal CP case and 6 OFDM symbols in an extended CP case. Accordingly, a mother matrix having N=6 can be designed. In this case, it is possible to eliminate ambiguity due to multiple peaks in timing synchronization since one subframe has no null subcarrier.

(86) Mother matrices based on a Costas array and cell ID/symbol modular will now be explained. However, if required, only one of the Costas array based mother matrix and cell ID/symbol modular based mother matrix is described for facilitation of explanation.

(87) A method of using a mother matrix generated based on N=12 is explained first.

(88) FIG. 22 shows punctured columns in a cell ID/symbol modular based mother matrix generated based on N=12 in a normal CP case. FIG. 23 shows cases in which the cell ID/symbol modular based mother matrix generated based on N=12 is applied to subframes. In FIG. 23, the left part corresponds to a normal CP case and the right part corresponds to an extended CP case. In FIG. 23, 0.sup.th, second, fifth and ninth columns are punctured in the normal CP case and 0.sup.th, first, second, third, sixth and ninth columns are punctured in the extended CP case. Here, the punctured columns correspond to regions where cell-specific RSs are located or regions where control channels are located.

(89) The mother matrix is constructed such that the last column is mapped to the last OFDM symbol.

(90) FIG. 24 shows an example of applying the mother matrix with N=12 to a MBSFN (Multimedia Broadcast Single Frequency Network) subframe. In FIG. 24, 0.sup.th and first columns are punctured.

(91) Furthermore, a mother matrix can be designed such that multiple peaks are not present in the time domain during puncturing in consideration of use of CRS or use of CRS with PRS.

(92) Particularly, puncturing can be performed with circular shift in consideration of a reuse pattern of CRS. For example, a CRS reuse pattern is [0,1,2,3,4,5,0,1,2,3,4,5].sup.T in the case of 1 Tx, which corresponds to the first column (column 0) in the above-described cell ID/symbol modular based mother matrix. Accordingly, it is possible to locate the first column on the CRS and puncture it. For example, in order to locate the first column of the mother matrix on the first CRS symbol (n.sub.sym=4) among CRSs except a control channel region, the mother matrix is circular-shifted to the right by 2 and puncturing is performed at the corresponding CRS position.

(93) FIG. 25 shows a result of cyclic shift of the matrix shown in FIG. 22 to the right by 2 in a normal CP case.

(94) FIG. 26 shows a result of cyclic shift of the matrix shown in FIG. 22 to the right by 3 in an extended CP case.

(95) FIG. 27 shows results obtained by applying the matrix of FIG. 25 and the matrix of FIG. 26 to subframes and performing puncturing. In FIG. 27, the left part corresponds to an extended CP case and the right part corresponds to an extended CP case.

(96) FIG. 28 shows a result obtained by applying the matrix of FIG. 25 to a MBSFN subframe and performing puncturing.

(97) As shown in FIGS. 25 to 28, it is possible to perform cyclic shift on the mother matrix and apply the cyclic-shifted mother matrix to a subframe.

(98) The first column (column 0) of [0,1,2,].sup.T can be located on the last CRS symbol of the subframe and punctured. FIG. 29 shows an example of locating the first column of the mother matrix with N=12 on the last CRS symbol of a subframe and performing puncturing in a normal CP case. FIG. 30 shows an example of locating the first column of the mother matrix with N=12 on the last CRS symbol of a MBSFN subframe and performing puncturing.

(99) A method of generating a mother matrix based on a Costas array will now be explained.

(100) FIG. 31 shows an exemplary Costas array having N=12. FIG. 32 shows a case in which the Costas array of FIG. 31 is applied to subframes. In FIG. 32, the left part shows a subframe corresponding to a normal CP case and the right part shows a subframe corresponding to an extended CP case. FIG. 33 shows a case in which the Costas array of FIG. 31 is applied to a MBSFN subframe.

(101) Meantime, a mother matrix with N=12 can be generated by extending a mother matrix with N=6 and performing puncturing for the mother matrix with N=6. Here, the operation of generating the mother matrix having N=12 from the mother matrix having N=6 is similar to the above description except that the mother matrix having N=6 is extended such that it is suited to a subframe.

(102) An extended matrix form is explained according to a Costas array based mother matrix generated based on N=6 (refer to FIGS. 17 and 18). Here, permutation can be performed in advance such that only columns corresponding to reused CRSs (0,1,2)(3,4,5,) are punctured. At this time, appropriate columns can be mapped.

(103) The following Expression 9 represents an example of a Costas array based mother matrix.

(104) $\begin{array}{cc}\begin{array}{cccccc}3& 2& 5& 0& 4& 1\\ 4& 3& 0& 1& 5& 2\\ 5& 4& 1& 2& 0& 3\\ 0& 5& 2& 3& 1& 4\\ 1& 0& 3& 4& 2& 5\\ 2& 1& 4& 5& 3& 0\end{array}& \left[\mathrm{Expression}9\right]\end{array}$

(105) The mother matrix of Expression 9 can be extended and applied to a subframe. FIG. 34 shows an example of applying a Costas array based mother matrix having N=6 to a subframe and performing puncturing in a normal CP case. FIG. 35 shows an example of applying a Costas array based mother matrix having N=6 to a subframe and performing puncturing in an extended CP case.

(106) Meantime, it is possible to apply permutation of an appropriate column and row to the mother matrix of Expression 9. FIG. 36 shows an example of applying a Costas array based mother matrix having N=6 according to an embodiment of the present invention to a subframe and performing puncturing. In FIG. 36, the left part corresponds to a normal CP case and the right part corresponds to an extended CP case.

(107) A mother matrix can be mapped onto a subframe such that cell IDs are evenly distributed in the overall frequency band when punctured. FIG. 37 shows an example of applying a Costas array based mother matrix having N=6 according to an embodiment of the present invention to a subframe and performing puncturing. In FIG. 37, the left part corresponds to a normal CP case and the right part corresponds to an extended CP case.

(108) A cell ID/symbol modular based mother matrix can be applied to a subframe. FIG. 38 shows an example of applying a cell ID/symbol modular based mother matrix having N=6 according to an embodiment of the present invention to a subframe and performing puncturing. In FIG. 38, the left part corresponds to a normal CP case and the right part corresponds to an extended CP case.

(109) (3) the Pattern Extended by Repeating at Least One Column or Row of a Mother Matrix

(110) This case includes a pattern extended by changing the order of at least two columns or rows of a mother matrix.

(111) This method extends a mother matrix smaller than a given resource in consideration of elements for eliminating multiple peaks during interfering and synchronization with CRSs (a subframe needs to have no null subcarrier). Here, if left and right CRS symbols have columns of the same reuse pattern as CRS, interference between CRS and PA-RS can be solved. FIG. 39 shows a pattern extended by repeating at least one column or row of a Costas array based mother matrix according to an embodiment of the present invention. FIG. 40 shows a pattern extended by repeating at least one column or row of a cell ID/symbol modular based mother matrix according to an embodiment of the present invention.

(112) (4) Mirroring Mapping

(113) A mother matrix of N, which is smaller than a given resource, can be extended using a mirroring pattern. In other words, when a mother matrix of N is repeated, the mother matrix can be mapped such that elements of the mother matrix are mirrored at the repetition boundary to become symmetrical. While the same patterns are collided when a mother matrix is extended through simple repetition, extension through mirroring can randomize collision to other subcarriers. Furthermore, when a mother matrix is extended to the frequency domain, mapping can be performed in reverse order of the mapping order of the upper half of the mother matrix. FIG. 41 shows a result of mirroring mapping using a Costas array according to an embodiment of the present invention. In FIG. 41, the left subframe corresponds to a normal CP case and the right subframe corresponds to an extended CP case.

(114) A PRS pattern for user equipment position estimation can be generated as follows. When frequency reuse is 6, PRS sequence r.sub.l,n.sub.s(m) in a slot n.sub.s is mapped to a complex-valued modulation symbol .sub.k,l.sup.(p) for position measurement according to the following Equation 10.

(115) $\begin{array}{cc}{k}_l=6m+k_l^{}{k}_l^{}=\left(\left(\left(v_{\mathrm{shift}}+1\right).Math.\left(l^{}+1\right)\right)\mathrm{mod}7\right)-1l^{}=\{\begin{array}{cc}\left(l-2\right)\mathrm{mod}6,& \mathrm{for}\mathrm{normal}\mathrm{CP}\\ l\mathrm{mod}6,& \mathrm{for}\mathrm{extended}\mathrm{CP}\end{array}m=0,1,\mathrm{.Math.},2.Math.N_{\mathrm{RB}}^{\mathrm{DL}}-1m^{}=m+N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-N_{\mathrm{RB}}^{\mathrm{DL}}{v}_{\mathrm{shift}}=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}6& \left[\mathrm{Equation}10\right]\end{array}$

(116) In Equation 10, N.sub.ID.sup.cell denotes PCI, N.sub.RB.sup.DL denotes a downlink bandwidth, and N.sub.RB.sup.max, DL denotes a maximum downlink bandwidth.

(117) FIG. 42 shows a PRS pattern according to an embodiment of the present invention for frequency reuse 6.

(118) Simulation of the performance of the PRS pattern will now be explained.

(119) Basic simulation parameters are shown in the following Table 1. Even if CRS and PRS can be used together, only PRS is used for position determination in order to compare different suggestions in terms of pure PRS performance. Es/Iot and RSRP (Reference Signal Received Power) are measured at user equipment in order to measure hearibility for each cell. Here, Es represents energy of a desired signal, and It represents power spectral density of an interference signal and it may be referred to as SINR in general.

(120) TABLE-US-00001 TABLE 1 Parameter Assumption Cell layout Hexagonal Grid, wrap around Inter-site distance 1732 m Antenna gain 15 dBi (3-sector antenna as defined in TR 36.942) Distance-dependent pathloss L = 128.1 + 37.6log.sub.10(R)(R in km) Carrier frequency 2 GHz Penetration loss and UE speed Indoor: 20 dB, 3 km/h for 1732 m (case 3) Carrier bandwidth 1.4, 3, 5, 10, 20 MHz eNB power 46 dBm UE noise figure 9 dB Lognormal shadowing standard 8 dB deviation Shadowing Between sites 0.5 correlation Between sectors 1 Correlation distance of shadowing 50 m Channel model ETU Network synchronization Synchronous Cyclic prefix Normal CP Positioning subframe Normal subframe Number of transmit antenna 1 CRS pattern Rel-8 PRS pattern FIG. 42 unless otherwise mentioned CRS transmission Always ON PRS boosting Dependent on PRS pattern Used RS for OTDOA measurement PRS only Number of receive antenna 2 Periodicity of positioning subframe 320 ms Number of accumulated consecutive 1, 2, 4 subframes for positioning subframe Number of PDCCH symbols 3 RS sequence Pseudo-random QPSK Probability of data blanking 100% in positioning subframe CRS/PRS transmission probability 100% Cell ID planning Planned, Unplanned Es/Iot threshold 14 dB RSRP threshold 127 dBm Max number of sites for OTDOA 10 measurement Timing measurement Replica based, coherent combining within a subframe Timing measurement window Ideal timing assumption: around ideal timing (for comparison of different PRS patterns) Practical timing assumption: 10 km (for all cases)

(121) If a measurement result satisfies a threshold value, replica based timing measurement is performed in order to study accuracy of estimated timing for a sensed cell. Performance of position determination depends on hearibility and accuracy of estimated timing. The accuracy of timing depends on auto correlation or cross correlation of PRS pattern and sequence. The hearibility depends on time and frequency reuse. Two assumptions depending on a timing search window are considered in order to study the influence of auto correlation profile from different PRS patterns.

(122) 1) Ideal Timing Assumption

(123) Timing measurement is performed around an ideal timing point corresponding to a shortest path. Auto correlation characteristic is hardly reflected in timing measurement because of PRS pattern. The performance of position determination mostly depends on hearibility.

(124) 2) Practical Timing Assumption

(125) A timing search window covers up to 10 km. The performance of position determination is partially affected by auto correlation performance in timing accuracy. Accordingly, the performance of position determination will affect hearibility and timing accuracy for a PRS pattern.

(126) According to the above description, an available number of PDCCH symbols is three when a system bandwidth is higher than 3 MHz and four when the system bandwidth is lower than 3 Mhz. In this case, two operations of user equipment are present in order to prevent position determination performance from being deteriorated. First, the user equipment always assumes a maximum number of PDCCH symbols. Second, a parameter about the number of PDCCH symbols is signaled to the user equipment. The first operation makes planning of a PRS pattern clear while the second operation requires additional overhead. For performance gain, the second si not distinct. According the first is advantageous for PRS pattern planning. Therefore, the present invention proposes planning of a PRS pattern on the assumption that the number of PDCCH symbols is three when N.sub.RB.sup.DL>10 and four when N.sub.RB.sup.DL10.

(127) However, as shown in FIG. 42, the number of PDCCH symbols is not varied with system bandwidth, and it is fixed to three all the time when PRS is transmitted. The PRS may be transmitted from the fourth OFDM symbol (when OFDM symbols in front on the time domain are numbered 0, 1, 2, . . . ) in case of normal CP. In case of extended CP, PRS may be punctured at the fourth OFDM symbol and transmitted from the fifth OFDM symbol since CRS is transmitted to the fourth OFDM symbol.

(128) Meantime, it is possible to construct symbols for PDCCH such that a maximum number of the symbols is three and transmit PRS for the remaining symbols. Furthermore, PRS may be punctured for OFDM symbols transmitting CRS. The relationship between PCI and PRS-ID will now be explained.

(129) Measurement of a current neighbor cell and report of the existing system (for example, Rel-8) are performed based on PCI. The number of PCIs is determined in consideration of effective cell ID planning Since cell planning for PRS-ID is required, PCI and PRS-ID need to have one-to-one relationship. The same format as the existing system can be reused for position report.

(130) Recently, LCS (Location Service) has pointed out PCI collision and confusion in a heterogeneous network. The probability of PCI collision depends on the number of PCIs that can be used for a cell. Since the number of PCIs allocated to HeNB/CGS cell depends on deployment, the probability of collision may not be insignificant.

(131) However, if 0 to 50 PCIs are stored at a system level for PCI collision, the probability of collision is not so high. Furthermore, the probability of collision can be further reduced according to a network based mechanism. Since downlink and uplink physical channels are transmitted based on PCI, PCI collision occurs again in other physical channels when PRS-ID is extended without PCI extension.

(132) In conclusion, PRS-ID extension is not a fundamental solution as long as PCI range is not extended.

(133) In associated with PCI confusion, user equipment may report global cell ID, for example.

(134) In this view, it is necessary to make the seriousness of CPI collision clear. Furthermore, PRS-ID extension is not a good solution.

(135) The present invention proposes one-to-one relationship between PCI and PRS-ID. A wider bandwidth increases time resolution, and thus it improves the performance of position determination definitely. FIG. 43 shows the performance of position determination depending on system bandwidth. As shown in FIG. 43, it is valid that the system bandwidth is limited to 10 MHz.

(136) The present invention proposes that a system bandwidth for a PRS pattern is limited to 10 Mhz (1.4 Mhz, 3 Mhz, 5 MHz, 10 Mhz).

(137) A PRS pattern may be time-varying between different subframes. A time-varying PRS pattern and a non-time-varying PRS pattern have a trade-off relation. While the time-varying PRS pattern is expected to improve position determination performance, additional signaling for notifying a subframe number is required.

(138) FIG. 44 shows position determination performance in a time-varying PRS pattern. It can be known that the performance of the mean of the time-varying PRS pattern is high on consecutive subframes, as compared to a non-time-varying PRS pattern. However, performance gain is not so high considering signaling overhead.

(139) Moreover, a non-time-varying PRS pattern is desirable when trade-off between the performance and additional performance is considered.

(140) Frequency and time reuse access have a trade-off relationship. FIG. 45 shows position determination performance with respect to orthogonal frequency reuse 6 and orthogonal time reuse 6. It can be known that all subcarriers in an OFDM symbol are occupied in time reuse. Although the performance of time reuse is not higher than the performance of frequency reuse due to its low energy, convergence of position determination can be improved to a level similar to that of the frequency reuse according to accumulation of a plurality of subframes.

(141) Therefore, orthogonal frequency reuse is more advantageous than orthogonal time reuse.

(142) PRS patterns will now be compared.

(143) First of all, two categories are explained.

(144) (1) Orthogonal Reuse Basis

(145) Different PRS patterns are generated according to orthogonal time or frequency shift. The number of patterns corresponds to time or frequency reuse. For example, six PRS patterns are present in case of reuse 6.

(146) Complexity reduction scheme is available.

(147) Multiple pits can be eliminated by removing null subcarriers in a subframe.

(148) Proposers include company A, company B, company C, company D and company E.

(149) (2) Fractional Reuse Basis

(150) Different PRS patterns are generated according to quasi-orthogonal time and/or frequency shift.

(151) The number of patterns corresponds to time and/or frequency reuse. For example, 96 (128) different PRS patterns are present in a normal CP case when three PDCCH symbols are assumed.

(152) Complexity can be reduced by the different PRS patterns.

(153) Fractional reuse can be performed by controlling the probability of PRS transmission from each cell.

(154) Multiple pits or poor auto correlation profile is present because of null subcarrier in a subframe. This characteristic is very important in neighbor cell measurement performed at a very low SINR level.

(155) Proposers include company F, company G, and company H.

(156) Among the above proposals, position determination performance is investigated. Different modulation sequences are applied to different PRS patterns. For calculation, boosting of different RSs depending on the PRS patterns is considered. Here, a boosting level makes transmission energy even in one OFDM symbol.

(157) Company A, company E: 6 dB

(158) Company F, company G: 9 dB

(159) Company B: 3 dB

(160) FIG. 46 shows a result of performance comparison of different PRS patterns on ideal timing assumption. Referring to FIG. 46, timing accuracies for the different PRS patterns are not different from each other because of a narrow timing measurement window.

(161) The pattern of company B has position determination accuracy lower than those of other companies because of low symbol energy (two OFDM symbols in one subframe). However, interference for a resource element given in one cell is mitigated when cell ID planning is applied.

(162) Hearibility from a fractional reuse based pattern is slightly lower due to larger frequency reuse 12.

(163) The ideal timing assumption cannot reflect characteristic of auto correlation profile from different PRS patterns.

(164) FIG. 47 shows a result of performance comparison of different PRS patterns on practical timing assumption.

(165) Referring to FIG. 47, it is apparent that orthogonal reuse based patterns (company A and company E) show the best performance because of better auto correlation profile (no null subcarrier is present in a subframe). The pattern of company B has the worst performance because of auto correlation profile having low energy due to null subcarrier and time reuse. For the pattern of company A, an orthogonal PRS pattern seems to collide with a PRS pattern of a neighbor cell for all PRS elements having different propagation delays.

(166) Position determination performances of fractional reuse based patterns (company F, company G, and company H) are poorer than that of the orthogonal reuse based pattern due to poor auto correlation profile.

(167) Since planning is performed in consideration of collision between CRS and PRS, the pattern of company F shows the best position determination performance.

(168) The proposals have different null subcarrier locations, and thus auto correlation profile depends on null subcarrier.

(169) When Es/Iot threshold value is determined from a pattern according to a false alarm rate, hearibility is not actually increased.

(170) The practical timing assumption can affect the auto correlation profile effectively from different PRS patterns.

(171) FIG. 48 is a block diagram of a device capable of being applied to a base station and user equipment and performing the above-described methods. Referring to FIG. 48, the device 100 includes a processing unit 101, a memory unit 102, an RF (Radio Frequency) unit 103, a display unit 104, and a user interface unit 105. A physical interface protocol layer is processed in the processing unit 101. The processing unit 101 provides a control plane and a user plane. A function of each layer can be executed in the processing unit 101. The processing unit 101 can perform the above-mentioned embodiments of the present invention. More specifically, the processing unit 101 can generate a subframe for user equipment position determination or receive the subframe to execute a function of determining the position of user equipment. The memory unit 102 is electrically connected to the processing unit 101 and stores an operating system, application and normal files. If the device 100 is user equipment, the display unit 104 can display various information items and can be implemented using LCD (Liquid Crystal Display, OLED (Organic Light Emitting Diode), etc. The user interface unit 105 may be combined with a conventional user interface such as a keypad, touch-screen, etc. The RF unit 103 is electrically connected to the processing unit 101 and transmits or receives RF signals.

(172) The embodiments described above are combinations of elements and features of the present invention. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, an embodiment of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. It is obvious to those skilled in the art that claims that are not explicitly cited in each other in the appended claims may be presented in combination as an embodiment of the present invention or included as a new claim by a subsequent amendment after the application is filed.

(173) In the present invention, user equipment can be replaced with a MS (Mobile Station), SS (Subscriber Station), MSS (Mobile Subscriber Station), or mobile terminal.

(174) The user equipment can use a cellular phone, PCS (Personal Communication Service) phone, GSM (Global System for Mobile) phone, WCDMA (Wideband CDMA) phone, MBS (Mobile Broadband System) phone, etc.

MODE FOR CARRYING OUT THE INVENTION

(175) The embodiments of the present invention can be implemented by various means. For example, the embodiments of the present invention can be implemented by hardware, firmware, software, or combination thereof.

(176) In a hardware configuration, the embodiments of the present invention may be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, microprocessors, etc.

(177) In a firmware or software configuration, the embodiments of the present invention can be implemented by a type of a module, a procedure, or a function, which performs functions or operations described above. Software code may be stored in a memory unit and then may be executed by a processor. The memory unit may be located inside or outside the processor to transmit and receive data to and from the processor through various means which are well known.

(178) Those skilled in the art will appreciate that the present invention may be embodied in other specific forms than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above description is therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all changes coming within the equivalency range of the invention are intended to be within the scope of the invention.

INDUSTRIAL APPLICABILITY

(179) The present invention can be used for terminals, base stations, or other equipment of a wireless mobile communication system.