Orthogonal pilot frequency sequence design method

The orthogonal pilot frequency sequence design method

technical field

The invention relates to a pilot frequency sequence design method, to a orthogonal pilot frequency sequence design method of.

background technology

On OFDM transmission technology's wireless communication system, the temporal frequency selective fading channel of metal in time and different rotor carrier the transmission signal decline degree of the. The is fixed system pilot symbols distributed generally the frequency two-dimensional grid space; the grid density jointly fixed by system and other channel quality, the expansion time and frequency Doppler line of the channel are greater, a pilot quantity of the precise channel estimation lower are multiple, therefore based on pilot symbols for estimating method generally the widespread use in fast channel decline. A based on pilot frequency sequence estimation method, the sequence length of long, generally of the clamped or symbols OFDM timing, the estimated algorithm is simple, a straight rod very high performance of the channel of slow speed. And due to the multi-antenna technology the multiple key preset application of MIMO-OFDM wireless communication system for providing a high data rate service transmission a low - speed of. The mainly aims at the MIMO-OFDM system for pilot frequency sequence-based method end on pilot frequency sequence design and estimating channel.

MIMO-OFDM system for consideration NT×NR the antenna, and subcarrier number of ALUMINIUM,) is a sampling time intervals of system, B=1/T is a system bandwidth; and TS= (K+Ng) T=NST is a symbol OFDM cycle, Ng is a circular prefix is usually, need to the ALUMINIUM? Ng ensuring consistency between datum power system, a ideal synchronous timing, wherein the antenna with the same time delay spectrum power, the multi-path) is L-SHAPED, at Ng≥L-1 to prevent between the marks interference (ISI), and time TS? LT, indicated of subcarrier system bandwidth is less than from relative bandwidth; and time domain a received signal and n time i ohm receiving antenna is ri (n); =Σ j=1NT&Sigmal=0L-1hij (n, l) uj (n-l); +&omegai (n),) >1≤i≤nr), a ∞≤n≤+∞ (1) nij (n, l), uj (n) and is a n j time transmitting antenna the l-shaped diameter of decline coefficient of the i ohm receiving antenna and a command signal and antenna j; ω i (n) is a n time receiving antenna i additive white Gaussian noises, when is 2 σω. By (1), multiple command signal, received signal and a writing-proof vector and u (n) is the two and (n), u2 (n); L, uNT (n)) is T) through >r (n) is the two resistor (n), r2 (n); L, rNR (n) through holes T); >&omega(n) is the two ω (1) n, ω (2) n, shape; ω NR (N) through a t-shaped through holes >

Wherein the clamping maximum delay L-SHAPED is less than Ng, the it is provided between the marks interference, a whole surface of the circular prefix; the n ohm OFDM mark time's received signal can be represented according <img and id= of idf0005 of file= of A20061002413800041.TIF of wi= " 392” he= " 21” img-content= of the positive img-format= of tif of/> <img id= of idf0006 of file= of A20061002413800042.TIF of wi= " 406” he= " 76” img-content= of the positive img-format= of tif of/><img id= of idf0007 of file= of A20061002413800043.TIF of wi= " 407” he= " 76” img-content= of the positive img-format= of tif of/><img id= of idf0008 of file= of the A20061002413800044.TIF wi= " 410” he= " 75” img-content= of the positive img-format= of tif of/><img id= of idf0009 of file= of A20061002413800045.TIF of wi= " 402” he= " 23” img-content= of the positive img-format= of tif of/>  is a Kronecker product, x (n) is a n time frequency domain multi-antenna the signal, <img id= of idf0010 of file= of A20061002413800046.TIF of wi= " 19” he= " 16” img-content= of the positive img-format= of tif of/> is KNR×KNT Uygur's block cyclic matrix <img id= of idf0011 of file= of A20061002413800047.TIF of wi= " 578” he= " 207” img-content= of the positive img-format= of tif of/>g (l) for receiving and transmitting antenna arrayThe middle of the shape of the matrix, wherein size of NR×NT, G (L) =h11 (L) h12 (L) Lh1NT (L) h21 (L) h22 (L) LH2NT (L) MMOMHNR1 (L) LLhNRNT (L)---(8) Through the > FFT converting frequency domain received signal of

<img id= of idf0013 of file= of A20061002413800051.TIF of wi= " 151” he= " 17” img-content= of the positive img-format= of tif of/><img id= of idf0014 of file= of A20061002413800052.TIF of wi= " 433” he= " 26” img-content= of the positive img-format= of tif of/> made UDFT=F⊗ INR),); >udft-1=f-1&circletimesINT),) > they is a Earthly Branch matrices. F is Fourier transform matrix, WKkl=e-j2π kl/K),) > SECTION has following: indicatedF=11L11WK1LWKK-1MMOM1WKK-1LWK (K-1) K-1)---(10) Through holes > using cover matrix's and matrix cyclic of the theorem of diagonalization, <img id= of idf0019 of file= of A20061002413800057.TIF of wi= " 378” he= " 21” img-content= of the positive img-format= of tif of/>diag {; &Lambdak DEG; =&Sigmal=0L-1G (l); e-j2&pikl/Nc) >); therefore obtaining y (n) is the Λ x (n) +z (n (13) z (n) is a frequency domain and vector, wherein DFT is a Earthly Branch conversion, which is exchange noise statistical property; z (n) are located element meets the independent with distributed Gaussian distribution, when for σ z2. Λ is inclined block substrate; &Lambda=H(n,0)L0MOM0LH(n, K-1)---(14) Through holes >h (n, k) =H11 (n, k) H12 (n, k) LH1NT (n, k) H21 (n, k) H22 (n.k) LH2NT (n, k) MMOMHNR1 (n, k) LLHNRNT (n, k)---(15) Through holes in > n the received signal of swage block carrier k can be represented for adjusting and (n, k); =&Sigmaj=1NTHij(n, k)xj(n, k)+z(n, k)---(16) Through holes > a vector form of y (n, k) =H (n, k) x (n, k) +z (n, k (17)

And x (n, ends of the two x1 (n, k), x2 (n, k); L, xNT (n, k) through T,) through >h (n, k) Hij element (N, K) is a n time to the i ohm receiving antenna for frequency responds Hij (N, K) =&Sigma the j transmitting antenna in subcarrier ends; anl=0L-1hij(n, l)WKkl---(18) Through holes > a writing-proof the vector formed hij= (hij (n, 0), hij (n, 1); L, hij (n, L-1) through T, 1<i<nr, 1<j<nt (19) is (17) is fixed to the see to the middle OF the diameter time domain in response j transmitting antenna to the i ohm receiving antenna in the MIMO-OFDM system, a signal transmitting multiple antennas' sub-carriers, wherein the sub-carriers experiences the inner decline, a receiver is an independent detection of the sub-carriers to machine primary information Bit. Need for estimating frequency domain channel to respond H (N, K) is detector beforehand, <img id= of idf0026 of file= of A20061002413800063.TIF of wi= " 54” he= " 20” img-content= of the positive img-format= of tif of/> can receive the direct estimation of the frequency domain pilot symbols, wherein the leads wireless channel is generally the sparse multi-path, and first estimation time domain in response value hij (n, l) and automatically according to (18) to obtain the frequency range decline coefficient of the pilot frequency sequence the estimation.

Wherein each antenna housing from multiple antenna for multi-path signal, a channel estimation performing the estimated on each receiving antenna cable. The access signals is i ohm receiving antenna K subcarrier a vector the form of y=Σ j=1NTXjgij+z---(20) Through holes > y= two adjusting (n, 0), easy (n, 1); L, easy (n, K-1) through Tz= two z (n, 0); z (n, 1), shape; z (n, K-1) TXj), for pilot frequency sequence K×K opposite angle, wherein the pilot frequency sequence length of P=K, ends of the diagonal element is xj (n, k), a pilot frequency sequence vector of defined is xj= (xj (n, 0), xj (n, 1); L, xj (n, P-1) through TXj=diag {xj} gij= (Hij (n, 0), Hij (n, 1); L, Hij (n, K-1) through a T (18) and define Fourier transform matrix F

; F&OverBar=11L11WK1LWKL-1MMOM1WKK-1LWK (K-1) L-1)---(21) Through holes > gij=Hij (n, 0) MHij (n, K-1); =F&OverBarhij (n, 0) Mhij (n, L-1); =F&OverBarhij---(22) Through holes of > (20) and (22) can perform a y=Σ ; j=1NTXjF‾ hij+z=Ah&OverBar+z---(23) Through holes > in one A= (X1F‾ , X2, F‾ , Shape; XNTF&OverBar);)); >h&overbarThe two hi1, hi2, shape; hiNT) T) >) is MIMO-OFDM j system to transmit the pilot frequency sequence of antenna is xj, wherein the end known; and square least received; the channel response a straight h&OverBar through the minimum a charging function; ; ^LS=argminh&OverBar{TerminalTerminal; y-Ah&OverBarTerminalTerminal2 DEG---(24) Through holes > computing value of h‾ ^= (AHA) is 1AHy---(25) Through holes > (AHA) is 1AH is a matrix A pseudo inverse, wherein the substrate is A size of P×LNT, Rank (A) =min (P, LNT), the work and P≥LNT, inner product matrix AHA is a non-singular is one, A pseudo inverse and is equal to the AHA) is 1AH, therefore the MIMO-OFDM system for training sequence's minimum length of the P≥LNT (26), wherein the pilot frequency sequence the transceiving two sides alarm oneself knowledge, a matrix A pseudo inverse of equal to or unit and memory, a speed of the terminal channel estimation method thereof. The LS channel estimation no need a known channel and noise statistical property; the computing complexity is a. A formula (23), and is a maximum likelihood to receive the estimating channel similar to respond, wherein the clamping and a additive and vain Gaussian, wherein covariance substrate is Rz=E {zzH DEG; =&sigmaz2I),) > channel vector's maximum likelihood estimation <img id= of idf0036 of file= of A20061002413800079.TIF of wi= " 23” he= " 23” img-content= of the positive img-format= of tif of/> is

; h‾ ^ML=argminh&OverBar{TerminalTerminal; y-Ah&OverBarTerminalTerminal; 2/&sigmaz2 DEG---(27) Through holes > compares (24) and (27), wherein the noise when hood is considered and a constant, obviously the maximum likelihood estimation and a square estimation is equal, wherein estimation's performance of the same.

Inspection (25), a writing-proof; h‾ ^=h&OverBarInterface (AHA) is 1AHz---(28) Through >); h&OverBar^= (H^i1, h^i2, shape; h^iNT) T,) through > in the differential the second one of the channel estimation and term. The channel estimation expectation is AN {; h&OverBarVoltage DEG; =h&OverBarInterface (AHA) is 1AHE {z DEG; =h&OverBar---(29) Through holes > of which can be known (28) is a unbiased estimate, the covariance matrix of the channel estimator output is Rh‾ ; ^=&sigma(z2 AHA) is 1) through > estimation averaging error (MSE); MSE=&sigmaz2LNTTr {(AHA) is 1 DEG---(31) Through holes > two B= (AHA) IS 1; the matrix size of LNT×LNTB=F‾ ; HX1HX1F‾ LF‾ HX1HXNTF‾ F‾ HX2HX1F‾ LF‾ HX2HXNTF‾ MOMF‾ HXNTHX1F‾ LF‾ HXNTHXNTF&OverBar---(32) Through holes > hypothesis pilot frequency sequence xj (n, k) is normally mould signal, andTerminalxj (n, k) 2=1 terminal, and F‾ ; HXjHXjF&OverBar=PI---(33) Through >) is not less than the geometric mean theorem by averaging operation, a averaging error of exchange for; MSE=σ z2LNT&Sigmaj=1LNT (B); j≥ σ z2LNTLNT&Pij=1LNT(B)jLNT---(34) Through holes > (B) j unit of THE matrix j diagonal member of matrix, inequality (34) when (B) 1= (B) 2=L= (B) LNT) through > taking a, and hada code (Hardamard) inequality; &Pij=1LNT (B); j&GreaterEqualdet(B); ; KLNT&GreaterEqualdet (B-1) is the two det (B)) is 1---(35) Through holes > inequality is opposite angle obtaining equal in a, B of therefore (34) and (35) can perform a

; MSE≥ &sigmaz2P---(36) Through >b) is opposite angle of the inclined element of substrate are all are (36) and equal a, the inferential reasoning method of applied to transmit the antenna of the plastic MIMO-OFDM system, and transmitting antenna value of non-referring in particular to claim 2 peculiar circumstances. From the plurality of the MIMO-OFDM system for pilot frequency sequence to the F‾ ; HXmHXnF‾ =0L&timesShape; m≠ ; nα IL&timesShape; m=n---(37) Through holes > α is a constant, 1≤m, n≤NT, at the time matrix AND is opposite angle, and diagonal member of substrate is equal.

The existing propose techniques the simple the pneumoelectric of two antenna meets the condition's production method of layer and pilot sequence's, can promote wherein to circumstances and <img id= of idf0050 of file= of A20061002413800093.TIF of wi= " 459” he= " 38” img-content= of the positive img-format= of tif of/> is leanedTerminalx1 (n, k) terminal the α, at the time matrix AHA diagonal member of matrix, wherein, when m=n, XmHXm=I)); >f&overbar; HXmHXmF‾ =F‾ HF‾ =PIL&timesAN---(39) Through holes in > non-diagonal element of matrix, wherein m≠n, diag {XmHXn DEG layer is the cycle of the 2NT-1 periodic sequence, only a work for pilot frequency sequence length; P&GreaterEqual2NT-1L) through the >, F‾ ; HXmHXnF‾ =0L&timesShape; m≠ n---(40) Through holes > pilot frequency sequence of therefore the formula (38) is installed while the length; P&GreaterEqual2NT-1L) through the > satisfies the orthogonality contact (37); the time's channel estimation a straight mean error's world of mortals.

When the MIMO-OFDM system for transmitting antenna are provided NT, wherein the channel and length is L-SHAPED, (25) and know on each receiving antenna needs to the estimated by a parameter is LNT, lower; P&GreaterEqual2NT-1L) through > the length pilot frequency sequence; the length sequence as the exponential growing along with the transmission antenna of; when the transmitting antenna are provided with (for example base station and more 4 the antenna), a pilot frequency sequence and lower is very long, so system power transmission to thereof.

invention content

The technical problem that the invention flowing solve is to provide the orthogonal pilot frequency sequence design method, the method may with a to the channel estimation averaging error requiring minimum length orthogonal pilot frequency sequence, wherein the reduced pilot sequence's, overhead messages of the MIMO-OFDM system transmission power.

In turn to solve the problem network, the technical solution of the invention is used: The orthogonal pilot frequency sequence design method: First; the definition pilot frequency sequence is composed of a matrix parallel bar vector; the orthogonal matrix for Fourier substrate; , And the pilot frequency sequence to harass, wherein added to harass sequence ck to theTerminaland ck terminal =1 be added the pilot frequency sequence without affect the other orthogonal.

The orthogonal pilot frequency sequence design method for the invention claims a obtaining widespread application in broadband wireless communication and mobile communication field, especially a OFDM transmission system with a one of prospects and fourth generation of mobile communication, multi-carrier and a. An for designing frequency domain pilot frequency sequence of transmission, and maintaining pilot frequency sequence of transmission for on the mould signal, improving receiver channel estimation the high-precision, wherein improving performance receiver.

detailed description of illustrated embodiments

The invention claims a orthogonal pilot frequency sequence design method: First; the definition pilot frequency sequence is composed of a matrix parallel bar vector; the orthogonal matrix for Fourier substrate; , And the pilot frequency sequence end of the perturbation, a causing harassed the time domain the signal of the ratio 1. The specific inferential reasoning process of the method is as follows: The system MIMO-OFDM the frequency domain pilot symbols transmitting of the frequency range sub-carriers, the inspection orthogonal pilot frequency sequence the other (37), wherein F is a unitary matrix, wherein Xj, 1≤j≤NT satisfies orthogonality contact; XmHXn=0L&timesShape; m≠ ; nα IL&timesShape; m=n---(41) Through holes >fxmhxnf further satisfies the orthogonality contact, inevitably, opposite angle of XmH pilot frequency sequence, a Xn and conjugated transpose matrix. Therefore when Xj, 1≤j≤NT of Fourier array substrate, satisfies the orthogonality contact inevitably, which is capable defined and substrate-processing the pilot frequency sequence of antenna is xm (n, k) =ej2 π kmL/K, m=0, shape; NT-1 (42) P=K is a sequence, length L is a maximum time length of the channel. The K≥LNT, a pilot frequency sequence capable of think is a motors and a matrix Fourier. At the time pilot symbols substrate; Xm=10L00ej2π mL/KL0MLOM00Lej2&pi(K-1)mL/K---(43) Through holes >

Satisfies the orthogonal pilot frequency sequence the other (37).

The emitting end frequency domain pilot frequency sequence converting the FFT, a time domain signal transmission of a writing-proof sm (n); =&Sigmak=0K-1xm (n, k); 1Kej2&pikn/K,0≤ ; n&leK-1---(44) Through holes running > (44), and time domain signal possibly is a pulse signal, wherein the pulling system is larger than the (PAPR), a consider used to harass groove Pm (N, K) =ckxm (N, K (45) is added according to harass sequence ck to theTerminaland ck terminal =1 be added the pilot frequency sequence without affect the other orthogonal (37) or (41), and normally multi-phase mould positioning pin (here A sequence); ck=ej4π &xik2/K,0≤ ; k&leK-1---(46) Through holes > ξ of the ALUMINIUM prime number, K is even number. Is added at the time in be time domain the signal transmission wherein the ratio 1.

A pilot frequency sequence is configured designed satisfies the orthogonality contact; and channel response's LS computing value (25) capable of simplifying is h‾ ^=AHy---(47) Through holes > wherein when it can be seen the pilot frequency sequence satisfies the orthogonal, wherein the voltage least square estimation with low realizing device of complexity.

Based on MIMO-OFDM system in the initially orthogonal pilot frequency sequence design method, for simulating method confirm to the pilot frequency sequence design method and device for estimating performance the circular claims, a simulation system for shown and a Table 1 on IEEE802.11a wireless and Hipperlan/2 similar OFDM configuration; the focusing channel time length and circular prefix length of the same, is 16; the clamping delay spectrum power and shown the digital 1 is a negative exponent), a stroke speed is 3km/h. Wherein ML and LS channel estimation realizing performance are the same; therefore the estimated algorithm for LS, a channel estimation averaging error (MSE) and weight target.

The 1MIMO-OFDM simulation system parameter parameter value transmission system AND 20MHz subcarrier are 64 K motor rotor type number 52 sub-intercarrier distance Δ f 312.5kHz signal duration TU3.2 μ sCP located in time 0.8 μ sOFDM mark cycle 4 μ s for coding convolutional coding, production (171,133) 8

The voltage-reducing decoded to Viterbi decoding sentence code rate 1/2 adjusting system QPSK and 16QAM with multiple digital 2×2 2) electrically connected with the MIMO-OFDM system soft when the transmitting antenna are respectively 2 and 4, which is orthogonal pilot frequency sequence the channel estimation's averaging error (MSE) performance, the existing technology without of initially is suitable for NT=2 orthogonal pilot, wherein the method according the invention claims a small is the antenna of orthogonal pilot frequency sequence design rope, shape as the NT=2, a pilot performance of the performance platform, the invention claims a design and performance of pilot rendering does the pilot performance, which is provided with a performance platform, wherein the orthogonal pilot frequency sequence estimation MSE performance of universal mortals, and then the antenna of, A pilot frequency interference between antenna without increasing.

Digital 3 charges is worked and subcarrier number of 128, wherein transmission speed of antenna, prior technology's the promoted method and invention of pilot design claims a method for estimating channel MSE performance of. Wherein the traditional orthogonal pilot design method other; P&GreaterEqual2NT-1L) through >, wherein the P=K=128, NT=4 orthogonal pilot design of achieve the MSE performance of universal mortals, the MSE performance of NT>4 worsened, and design method for the invention claims with the antenna of robustness, which achieve the MSE performance of NT=4,5,8 the universal of mortals.

Digital 4 in digital 5) are provided with the convolution encodings 64 of the QPSK modulation and 16QAM modulation 2×2 MIMO-OFDM system BER performance, wherein the coding mode is very high; the gain for orthogonal pilot frequency sequence design with reduced; and a through the series design of the 10-5 performance under the QPSK the position of the gain and a ideal channel estimation of 0.8dB without and 0.1dB disparity, and gain and without differs 0.2dB with the ideal channel estimation of 1.8dB the lower 16QAM modulation. From which are used the invention claims a orthogonal pilot frequency sequence design method of can reduce the sequence the length, improving performance system.

Brief description for drawings

Digital 1 is a channel time delay spectrum power.

Digital 2) is sequence length is 52, wherein the transmitting antenna value is 2 and 4 MSE performance comparisons schematic drawing.

Digital 3) is sequence length is 128; and transmitting the number of 4, 5 and 8 MSE performance comparisons schematic drawing.

Digital is 4 QPSK or the BER performance comparing the schematic drawing.

Digital is 5 16QAM or the BER performance said drawing schematic.