TWI239179B - Channel estimation in orthogonal frequency-division multiplexing (OFDM) systems - Google Patents

Abstract

A system and method for estimating channel characteristics in orthogonal frequency-division multiplexing (OFDM) systems with transmitter diversity is presented. The disclosed approach is compatible with the institute of electrical and electronics engineers (IEEE) ""wireless local area network (LAN) medium access control (MAC) and physical layer (PHY) specification."" In the disclosed system and method, an additional training symbol is transmitted during the data period. This provides additional information that may be used to more accurately estimate channel characteristics.

Description

1239179

说明 Description of the invention: [Technical field to which the invention belongs], invents a communication system and method, and particularly relates to a system and method for estimating channel characteristic values, which are applied to orthogonal frequency division of a transmission diversity architecture. Engineering system. " [Previous Technology] Radio-frequency local area network system operation is strictly controlled by the US federal agencies. For example, the use of 5.15-5. 25 GHz, 5. 25-5 · 35 GHz and 5.725-5 · 825 GHz unlicensed national information structure (U-NII) is subject to U.S. federal regulations Regulation (CFR) 15.407 Section 47. Not only does the US Federal Regulations regulate the use of radio frequency networks, other organizations such as the Institute of Electrical and Electronics

Engineers (IEEE) also develop technical specifications for wireless networks to ensure interoperability of wireless systems made by different manufacturers. For example, the "Wireless LAN Medium Access Control Layer and Physical Layer Specification: 5Ghz Band High-Speed Physical Layer" (Wireless LAN Medium Access Control (MAC) and

Physical Layer (PHY) Specifications: High-Speed Physical Layer in the 5 GHz Band, hereinafter referred to as the IEEE 5Ghz standard, sets some specifications for systems operating in the 5Ghz 123917¾ band. In the IEEE 5Ghz standard, a part of it is about a physical layer convergence procedure (PLCP) sublayer of an orthogonal frequency division multiplexing (OFDM). Figure A shows the frame format of a Presentation Protocol Data Unit (PPDU), one of the IEEE 5Ghz standards. As shown in Figure A, the frame of the display agreement data unit includes: a short-training period 110;-a long training period 120, followed by the short training period After no; a signaling period 130 followed by the long training period 120; and a plurality of data periods 140, 142 and 144 followed after the signal period 130. According to the IEEE 5Ghz standard, the long training period 120, signal period 130, and multiple data periods 140, 142, and 144 all include a guard time interval (gUar (j intervai, gi). _ The short training period 110 contains ten symbols Yuan (price, △ ·... "), The functions are signal detection, preliminary frequency acquisition (coarse-freqUency acquisition), diversity reception selection (diversity selection), and other functions developed by 臓 5Ghz. The full specification for the short training period 110 is defined in detail in the 1 £ leg 5Ghz standard, which is not covered here anymore 7 1239179

Do more in-depth discussions. The long training period 120 includes a guard time interval (GI2) and two long training symbols (knife and%). According to the IEEE 5Ghz standard, each long training symbol is composed of 53 subcarriers, and its DC voltage value is zero, and its content is generated by a series of digital sequences / operations. The number sequence J is as follows: X = {1,1, -1, -1,1,1, -1,1, -1,1,1,1,1,1,1, -1, -1,1 , 1, —1,1—1,11m 1, -1, -i, i, i, -i, i, -i, i, -i, -i, -i, _i, -i, i, i , -I, -l, i, —11, —ΐ, ΐ, ΐ, ι, ΐ} [Ειι · 1] · In addition, the IEEE 5Ghz standard defines the operation function for generating long training symbols as y 53 [ Eq · 2], X (') = X ((~ TGI2)

k = Q where is the time axis symbol of one of the long training symbols, whose function is the spectral shaping of the signal; 々 is a subcarrier argument; iU) is a training symbol defined by Eq. 1. One parameter of the element; and-is the guard time interval. In the IEEE 5Ghz standard, the value is 6 s. In addition to the definition of the long training symbols (according to Yang. &Amp;), IEEE 5Ghz also specifies the number of long training symbols to be two (71 and the knife) to increase the accuracy of channel estimation. Also, the IEEE 5Ghz standard It is stipulated that the content of the first Nagasaki rune element second Nagasaki rune element Z is the same. Therefore, the same long run training element I is designed, the first long training rune element / 155 1239179 and the younger second long rune element / 165 scale Light _ two-pass diversity diversity orthogonal frequency division multiplexing system (such as: the second section 120. Therefore, the pair 260 transmits the following: ~ shown in the figure) 'a first pass in the long training period Within 120 minutes / brain in the-channel and;-, practice symbol element / threaten and pass in the signal of paragraph 130 within the time of 'and again, pass 4 is expected to be in the first-⑶ shouted after the 142 At that time, it was called Chuan Na and A and 190a on the _th channel. Similarly, a second transmitter 265 transmits the following: ⑴ Within the time of the long training period, it transmits the two long training symbols Ji55b and J 165b on a second channel; (2) within 13 hours of the bluffing period, send signal information SHOb on the second channel; (3) During the subsequent data periods 140 and 142, the data Λ 18〇b and 190b are transmitted on the second channel and. A receiver 205 receives the transmission signals from the first and second transmitters, and the Receive 5 Fan sign is a function of the transmission symbol and channel characteristic. 1239179 After removing the guard time interval, each receiver ^ follows an inverse Fourier transform operation. Thus, for _ as shown in the second figure The two shown in the figure have a round diversity orthogonal frequency division multiplexing system. The receiving signals on the frequency axis include the first receiving signal 215, the second receiving symbol D 225, and the third receiving symbol t'3 235. The first receiver receives payment ΤΙ 245 and the fifth receiving symbol K 255. The first receiving symbol Γι 215 can be expressed as: yi = (ha ^) ^ Hb.X) + zu [Eq. 3] · where When money receives noise, tolerance and spread are channel-specific females on the frequency axis, and it is assumed that the peak remains at the frame duratiQn, and the transmission delay of the two channels is also assumed to be the same. Since the same-long training symbols are sent to the two transmitters of the two transmission diversity systems, Eq · 3 can be simplified to · · = {ΗΑ + ΗΒ) .χ + Zι. [Eq. 4]. Similarly , In the subsequent receiving data block, the second receiving symbol τ, 2 225, the third receiving symbol T′3 235, the fourth receiving symbol T′4 245, and the fifth receiving symbol Ή255 may be expressed as: [Eq · 5 ], [Eq. 6], [Eq. 7], Υ2 = (^ + ^) · χ + ζ2, Y3 = (HA + HBys + Z3, Y4 = H + HB.Dm + Z4, and [—Ha · DA2 + Ηβ · DB2 + Z5 [Eq · 8] · Ι259Κ79ι [Eq. 9], combining Eqs. 4 and 5, the following equation can be obtained: (^ Γ2) .ζ · = (^ + ^). (2 | χ | 2) + (Zι + ζ2) χ.5 After shifting the term, it can be rewritten as: ηα + ηβ = suitable 2 2, or more precisely: HA (k) + HB (k) = (Zx {k ) + Z2 {k))-X (k) 2-2 [Eq. 10], where #;!: The number of orthogonal sub-purity sub-remainders, and} is the argument of the subcarrier. In Eq · 1, for all buttons, · e {± 1}, so the transmission of the complex number of symbols / 麟 is also the same as the transmission of symbols. Also, because 彻 e㈣, the square term of the transmission symbol iU) 丨 / ⑷ 丨 2 will be Bu. In addition, because the male) e㈣, (then + then) / (magic sum (then + thru)), generally come It is the same. Ignoring the noise term, the comprehensive eigenvalues of the two channels (and the second channel) can be estimated by the following equation:

k = lL, N

[Eq. 11], Although Eq. Π provides a method for calculating comprehensive Tongju㈣, it is obvious that 1239179--*---... .........-..... ..... 一 ......... Repeatedly transmitting the symbol J does not help distinguish the channel feature values of the side channels (forbearance and forbearance). In other words, β Erkou is a single transmission channel (Nuhezhan), and a single symbol γ is transmitted. Therefore, the channel characteristic value of the system can be expressed by a single binary equation. Only the integrated channel characteristic value can be calculated. Learned. In addition, the repeated transmission of symbols increases the signal-to-noise ratio (Signal—10—noise), but the improvement of the signal-to-noise ratio cannot help calculate the characteristic value of individual channels. Although there are currently some complex algorithms that can separate the feature value of individual channels from the feature value of integrated channels, they need to make additional assumptions about channel characteristics before they can be correctly estimated. Eigenvalues of individual channels. Therefore, these channel estimation algorithms are only suitable for avoiding the assumption that these assumptions hold. U is the high computational complexity of these channel / channel estimation algorithms. When these two transmission diversity systems are expanded to more support transmission architectures (such as · Two or four transmissions), the computational complexity will grow exponentially. Therefore, there is a need in this industry for which there is no solution to solve the above-mentioned shortcomings and inadequacy of existing algorithms. [Summary of the Invention] The present invention is a method and method of the side channel probabilistic value, which adopts the orthogonal frequency division multiplexing system environment of the transmission diversity architecture. 12 1239 Difficult, sloppy. / In short, the embodiment of the system of the present invention includes an architecture-transmission unit, the function of which is to transmit in the first period, training to sail in the first channel, and to transmit the training symbol. Yuan Yum in the second miscellaneous series of symbols Yuan-Wei Gongche Fu Yuan ^ the first-channel; at the same time, the lion 丨 practice symbol Yuan _ negative value complex number of women in this first channel. In addition, the present invention provides a channel characteristic value estimation method, which is applied to an orthogonal frequency division multiplexing system environment adopting a transmission diversity architecture. The operation steps of the method of the present invention include: transmitting a training symbol at the _th period to m at the same time, and training the symbol at the second channel; transmitting a plural number of the training symbol at the second period. A conjugate symbol is on the first channel; at the same time, a negative complex conjugate symbol of one of the training symbols is transmitted on the second channel. After reviewing the following illustrations and implementations, the artist should easily understand other systems, methods, functions, and advantages of the present invention. Moreover, all such systems, methods, functions and advantages are within the patent scope of the present invention. [Embodiment] The embodiment shown in the drawings will be described in detail below. Although some of the embodiments have been shown in the above figure, the embodiments of the present invention are not limited thereto; on the contrary, the scope of the present invention covers other related, partially modified or equivalent embodiments. 13 12 79 79 Some embodiments of the present invention will be described below. In these embodiments, the extra __ element is used to achieve the precise side channel feature_ purpose. Unlike previous systems and methods that required red computing power or extra-multiple transmission diversity, additional operating assumptions, the embodiments of the present invention only require simple computing power and do less for multi-transmission and centralized systems. Operating assumptions. The second chart A and the second chart show an embodiment of a system for estimating the channel characteristic value. The third chart A shows the first symbol transmitted by the transmitter, and the second chart shows the first symbol. Symbols transmitted by the two transmitters. Figures A and B show the physical layer convergence procedure (PLCP) pre-e field of the present invention, and the power and material signals are synchronized. As shown in Figures 3A and 3B, the copper block of the physical layer convergence procedure includes: short training period 31G,-long training period coffee, following this short training period 31Q;-signal period 33 °, After the long training period of 32 o'clock; and a plurality of data reference sections 340 342 344, etc. 'are connected after the signal period of 33 o. According to the ieee 5 Han standard, the short training period 310, the long training period 32, the signal period 33, and the multi-data period 340, 342, and 344 all include a guard time interval. Therefore, 'as shown in the third A', the first-wheeler transmits symbols during the short training period 310, according to the leg 5Ghz standard. When the training symbols are transmitted, the long training symbols ^ 14 and JT 365a are transmitted during the long training period 320. Here, uppercase / represents a group of frequency axis symbols of an orthogonal frequency division multiplexing system. J can be regarded as a vector including water elements, and # is the number of subcarriers of the orthogonal frequency division multiplexing system. The elements of the symbol J are transmitted by the first subcarrier. It must be known that before transmitting through a transmitting antenna, the symbol / will first undergo an inverse Fourier transform operation to become a time axis signal, and a cyclic prefix is added. , And then use a radio frequency module to convert into a radio frequency analog signal. Immediately after the repeated transmission of the symbol J, the signal data ^ 37〇a is transmitted in the signal period 330 and the training period 330. After the signal data is transmitted, one of the long training symbols, a total of 385a, is transmitted at the -data period of 34. As mentioned above, because each element of I is a real nuinber, naturally, every element of the family is also a real number. Also, because each element in j is a real number, it is the same. Lu However, it must be known that outside of the 5Ghz standard, 7 does not have to be limited to a real number, it can be a complex number, and has imaginary elements. Similarly, as shown in FIG. 3B, the second transmitter transmits the linguistic test period 31 () according to the dirty standard. When the hybrid Lin Fuyuan ship, the long training session / 355b and j 365b are transmitted during the long training period 32 {). Immediately after the symbol, the weight 15 1239179 is retransmitted, and the signal data S 370b is transmitted in the signal period 330. After transmitting the signal data S370b, one of the 'long training symbols', a negative complex conjugate symbol-/ 385b, is transmitted in a first data period 340. As mentioned above, because each element in / is a real number, naturally, every element in-/ is also a real number. Also, it must be known that outside of the IEEE 5Ghz standard, / is not necessarily limited to real numbers, can be complex numbers, and have imaginary elements. Based on this knowledge, if J is a plural number, the symbols transmitted in the periods 385a and 385b can be (-i; Nai, U; Yu) or (para-private) symbol couples. To simplify the description, the following description will use the symbol couple (/ <-/ time) as an example. As described above, the embodiment of the present invention is not only a system for repeatedly transmitting training symbols 7, the second A picture and the third B picture, but also adding a transmission conjugate symbol / on the first channel, and Teleport negative symbols. The benefits of adding teleportation symbols γ and ^^ will be described below, and illustrated with the fourth figure. The fourth figure shows a two-branch transmission diversity orthogonal frequency division multiplexing system, which includes a wireless device 470 and a receiver 405. The wireless device 47 may be an access point unit of a wireless local area network, a wireless LAN card, a cellular phone, a wireless personal digital assistant (personal postal assistant, PDA), or It is a portable computer with wireless transmission function. As shown in the fourth figure, the wireless device 470 includes two transmitters 460 and 465, which transmit data in a normal 16 crossover multiplexing environment. The receiver 405 receives signals transmitted by the two transmitters 460 and 465. As shown in the fourth figure, a first channel transfer function (yK) changes the signal transmitted by the first transmitter 460, and a second channel transfer function is caused by the signal transmitted by the second transmitter 465. change. This channel transfer function is the channel characteristic value. When Tian Yuanzhang got Ju Ju 460 and the second transmitter 465 to transmit the symbol j (the steps are as follows: first perform the inverse Fourier miscellaneous operation on the symbol j to generate the _ coffee axis signal especially; then add-cycle The w-tuple, Charm, replaces the complement with a radio-frequency analog signal, and transmits xCp using a transmission antenna. The T-th receiving symbol TWi5 on the frequency axis can be expressed as: I⑻ 斗 ⑻.⑻, [Eq. 12] Where% is the noise of the first received symbol. Because the same training symbol it J is transmitted on this second transmission diversity transmitter, EQ · 12 can be simplified as: Ά ^ ΗΛ ^ ΗΒ) .χ ^ Zχ [Eq · 13]. Similar because of the same training The symbol is transmitted again. The second receiving symbol T, 2 425 carried by the two transmitters 460 and 5 can be expressed as: υ ^ ηλ ^ ηβ \ χ ^ ζ [Eq · 14]. Also, if the signal The data 370a is then transmitted as a third receiving symbol TW35, 1239179 and the third receiving symbol T, 3 435 is: ^ {ha + hb) .s + z ^ LEq · 15],… on the 5 疋 frequency axis Signal information. In one embodiment, when transmitting the signal data, "the complex number of long training symbols 70 / 385a is transmitted to the first-password transmitter and becomes the fourth receiving symbol. The number of long training symbols is equal to the symbol. Wu / passing thought on the second transmitter 465 becomes the fourth receiving symbol η peach. As mentioned above, because J is a real number, the complex conjugate symbol and the negative complex number symbol / also P Real numbers. In addition, 'for the same reason, the symbols have the following relations: [Eq · 16], [Eq · 17], and [Eq · 18] ·' The fourth receiving symbol T, 4 445 can be expressed as · [Eq · 19],

丨 Double 々) 丨 2 = 1. Therefore, according to the IEEE 5Ghz standard ^ = (^ .χ) + (// β. (-Χ)) + ζ4, or, further simplified to: [EQ. 20]. Combining 13 * 2Q, we can provide a method Calculate μ and other values separately. In other words, 'different from the prior art, only the integrated channel characteristic values can be calculated (pure ⑽, Ben 18 1239179 invention can be calculated separately for tolerance and development, because: (Y ^ Y,) ^ r = ((HA + HB ) -X + Z ^ r + ((HA-HB) ^ X + Z, yX ^ = 2Ηα · \ χ \ 2 ^ (Z ^ Z4) · χ * [Eq. 21]. It must be noted here that Eq . Each variable item in the formula 21 is a frequency axis signal of an orthogonal frequency division multiplex symbol. If it is described by the angle of the subcarrier, Eq. 21 can be rewritten as · (y (A :) + r4⑹). Φ0 · = 2% (Magic · | × ⑻f + hOSO + Z] ⑻). Z * ⑻, A: = 1, L #, [Eq · 22], where water is the subcarrier in the orthogonal frequency division multiplexing system Number, and 々 is the argument of the subcarrier. After calculating Eci. 13 and 20, the channel transfer function can be obtained by the following equation.

[Eq. 23]. Ηα (/ 〇_ (^) + n (k)) · X (k) (Z, (k) + Z4 (k)) > X (k) According to Eq. 23, It can be estimated as: [Eq. 24], 联 _ 巧)) · trip, called, N or, simplified expression is: 19 1239179 [Eq. 25]. It must be noted here that Eqs. 24 and 25 equations Among them, an estimation error (estimationerror) is related to the noise term (say Shi) / 2. In general, the mean of the estimation error of the noise term (mean) is 0 (^ :( 4 + 24) 1/9 = 0, which is the statistical expectation function). Moreover, the variance of the estimation error is 4/2 (var ((Z + 石) // 2) = variXZ + ^ / ^ hvarix ^ + zj /]): ^ /〗, where var () is the statistics Function of the variance value, and the variance values of 2 and ^ are assumed to be σ). The eigenvalues of the second channel can also be calculated in a similar manner: +-//,). × + ZZ4) .χ * ^ 2ΗΒ · \ Χ \ 2 ^ {zx-z, \ r [Eq. 26] , Which is further simplified as: [Eq. 27].

_ (^-r4) .x izx-z, yx H 「-2 2— or HAk) _ (m) -uk)) 'X (k) {zx (k) -zA (k) yx (k) [Eq. 28]. Therefore, the exhibition can be estimated as: 20 1239179 2 [Eq. 29]. As in Eqs · 24 and 25, one of Eqs · 28 〇 and 29 is estimated. The error is also related to The noise term (Mei J / 2 is related. Therefore, the average value of the estimation error of the flood term is 02 // 2 > 〇), and the variation value of the estimation error is ^ (var ((^ i-^) // 2) = var ((ii-^) / 2) = a ^ / 2) 〇 From the derivation of the equation of Eqs. 12 JL 29, it can be seen that by transmitting Symbols / and-/, the characteristic values of each individual channel can be accurately calculated. Therefore, it is not limited to estimating the characteristic value of the integrated channel, the method of the present invention can also be used to estimate the characteristic value of the individual channel. _ · The present invention In another embodiment, by combining Eqs · 13, 14, and 20, better signal integrity and lower estimation error can be obtained. Because Eqs · 13 and 14 repeatedly transmit the same training symbols /, and then receive signals , So combining these two equations can be regarded as a further spring signal averaging. Therefore, The benefits of increasing the signal-to-noise ratio brought by repeatedly transmitting the training symbol J, the individual channel characteristic values can be calculated according to the following equation: (W 2¾), = 4 see · X | 2 + (4 + Zn2 + 2Z4) · [Eq · 3 0], and 21 12391¾ [Eq. 31],

Ha = (jllI2 + 274) -X (Z1 + Z2 + 2Z4). Χ 4 4 or 'equivalent expression is: HA (k) =: (moxibustion) + 2r4 ⑷) · male) _ (Zx (k) + Z2 ⑷ + 2Z4 ⑷) · X⑻ 7 _ιτ λγ

4 ~ λ, A: = i5L? 7V

[Eq. 32],

Therefore, the tolerance can be estimated as: [Eq · 33] · HA (ir \ ^ k \ ^ Y2 (k) ^ 2YA (k))-X (k) 4 Moreover, it is different from EqS. 24, 25, 28 and In the calculation of 29, the estimation error caused by the noise term in Eq. 32 is (Don't ^ + 22) // 4. Therefore, the average value of the estimation error is 0 (double (/ + 2 + 2 stone) // 4) = 0), and the variation value of the estimation error is 3 # / 8 (var ((Z + ^ f2Z) J / 4) = var ((i! + Z + 2Z4) / 4) = 3a] / 8, where the variation of /, name and Z is assumed to be 4). It can be seen from Eq. 32 that the variation of the estimation error is reduced, and the estimation accuracy is improved. Similarly, the eigenvalue chip of the second channel can also be obtained by the following equation: k = i, L, N [Eq. 34], In the above formula, the average value of the estimation error is 0 (double U + Z2-2Z ) i74) = 〇) and the variation of the estimation error is 3σ〗 〖/ 8 (var (U + Shi-22) // 4) = 22 1239179 var (U + Mod-2 Magic / 4) = 308, where it is assumed that%, The variance of the name and% is g). In general, g, by transmitting an additional long training symbol I, or a complex conjugate payment element of the symbol / and a negative complex conjugate symbol-/, the variation of the estimation error can be further reduced. For the above-mentioned multi-transmission diversity system, another embodiment of the present invention can be used as a method to estimate channel characteristic values. The fifth and sixth figures show embodiments of this method. The fifth figure is a flowchart showing the implementation steps of the method, which operates on one or two transmission diversity quadrature scale H devices 470. According to the dirty 5Ghz, the signals transmitted in the fifth picture all include the guard time interval. As shown in the fifth figure, during a first period, a training symbol is transmitted on the first and second channels (step 52). In one embodiment, the wireless device 470 includes a first channel transmission unit (transmit 10 to 555 and a second channel transmission unit 565, respectively, for transmitting information to the first channel and the second channel. Immediately after the first channel After the training symbols are transmitted during the period (step 52), in the second time ^, a plurality of symbols of the pay unit are transmitted to the first channel (step 530). At the same time, Lu Lu The time period towel, the negative-plural value of the symbol element is transmitted to the second channel (step 540). If the channel estimation method is based on the IEEE 5Ghz standard, the first period is a long training period for the entity layer to receive privacy. The time frame of the slot slot of the sequence, and the second period is one of the time period and the expected period. 23 1239179 The sixth diagram is a flowchart showing a method to estimate the characteristic value of the channel and is implemented in the receiver 405. As shown in the sixth figure, a receiver receives a symbol (step C). After the symbol is received, an individual channel effect can be calculated from the receiving symbol (step 63). This individual channel effect is available Take the characteristic value of the side_channel (step_. In the example, the receiver 405 includes a receiving unit 625, an individual channel effect calculation unit 635, and an estimation unit 645, which are divided into the sixth picture of receiving (step 620), side channel effect calculation (step 630), and estimation ( Step 64) and other steps. Also, in an exemplary embodiment, the received symbol is the analog signal of the transmission signal in the fifth figure. Also, for a 10,000 transmission diversity (^ " branch) system, the reception The receiver 405 receives / 7 symbols in step 620, each of which is a signal after the same training symbols are transformed by different channel effects to form a system of 77 / 7-element simultaneous equations. See Eqs. From the equations of 12 to 34, the π channel characteristic values can be calculated individually. As can be seen from the fifth and sixth graphs, the embodiment of the method can obtain a more accurate estimation of the individual channel characteristic values, and It is not just the estimation of the integrated channel characteristic value, or additional assumptions must be made on the channel characteristic value. Although the exemplary embodiments of the present invention have been mentioned above, practitioners should understand that the above embodiments of the present invention can be easily changed. And changes. For example: For the sake of explanation, one or two transmission diversity systems are shown above. However, practitioners should understand that the method mentioned above can be extended to multiple transmission diversity systems 24 1239179 system (three, four or more). Multi-transmission). In addition, although the fourth picture shows the antenna of the wireless device, the artist should understand that the transmission wheel!! It can be a wireless LAN access point unit, a wireless LAN card, -Cellular phone,-Wireless personal digital assistant, or other similar wireless device that can send and receive data. Also, "Although in the embodiment of the present invention, an additional training symbol is transmitted at a specific time period, this artist It should be understood that the additional training symbol can also be transmitted in the time period of Lai data. Moreover, although Figures 3A and 3B only show an additional training symbol (such as the long training symbol) (Combined with multiple sisters or singularity with common wife), f this art face _, more follow-on symbols can also be applied to this system 'to improve the signal-to-noise ratio in channel estimation, and for Calculate side channel characteristics of multi-branch transmission diversity systems (more than two branches) . In addition, the oil embodiments of the present invention all follow the IEEE 5Ghz standard. Those skilled in the art should understand that the method and system of the present invention can be extended to the transmission environment of any orthogonal frequency division multiplexing. In addition, although this standard is used to describe some of the concepts of the present invention, those skilled in the art should understand that the system and method of this day and month are also applicable to the class 2 bird standard (job: 802.11g) or Other similar wireless standards, no matter what operating frequency band is used, such changes or modifications should be within the scope of the patent of the present invention. [Schematic explanation] Lu In order to explain the mosquito resilience in this article, let me give you some instructions and a simple explanation. Figures -A and -B are packet message block diagrams, showing the standard framework for presenting a communication protocol (presentati〇n pr0t〇c〇1 Data, pp 卯). . The second picture is a frame-turning mouth _ two transmission division orthogonal frequency division multiplexing system, 25 1239179 The operation mode follows the IEEE 5Ghz standard. Figures 3A and 3B illustrate an embodiment of a system of the present invention for estimating channel characteristic values. The fourth figure is an architecture diagram. According to an embodiment of the present invention, a channel eigenvalue estimation system is used for one or two transmission diversity orthogonal frequency division multiplexing systems. The fifth figure is a flowchart illustrating one embodiment of a method of the present invention, which is applied to a transmitter of one or two transmission diversity orthogonal frequency division multiplexing systems to estimate channel characteristic values. The sixth diagram is a flowchart illustrating one embodiment of a method of the present invention, which is applied to one receiver end of a transmission diversity orthogonal orthogonal division multiplexing system for estimating channel characteristic values. [Illustration of graphical symbols] 110 short training period 120 long training period 130 signal period 140 data period 142 data period 144 data period 150 first long training symbol 155 first long training symbol J 160 second long training symbol 165 Two long training symbols / 26 1239179 170 signal data S 180 transmission data Λ 190 transmission data and 155a long training symbols / *

155b long training symbol J 165a long training symbol J '165b long training symbol / 170a signal data S 170b signal data S 180a transmission data Λ 180b transmission data Λ 190a transmission data and 190b transmission data and 205 receiver 215 first Received symbol Γ! 225 Second received symbol Γ2 235 Third received symbol Γ3. 245 Fourth received symbol Γ4

255 Fifth receiving symbol TS 260 First transmitter 265 Second transmitter 310 Short training period 320 Long training period 330 Signal period _

340 information riding section W 342 data period 344 data period 355a long training symbol / 355b long training symbol / 365a long training symbol / 365b long training symbol /

370a signal data S 370b signal data S 385a long training symbol / one complex conjugate symbol / 385b long training symbol / one negative complex conjugate symbol_ / 27 1239179 390a transmission data / ¾ 390b transmission data and 405 receiver 415 first receiving symbol Γ! '425 second receiving symbol Tf2 435 third receiving symbol Ή " 445 fourth receiving symbol Ή 460 first transmitter 465 second transmitter 470 wireless device 555 first One-channel transmission unit 565 Second-channel transmission unit 625 Receiving unit 635 Calculation unit for individual channel effects 645 Estimation unit

28

Claims (1)

Patent application scope: The method of estimating channel characteristic values is applied to one or two transmission diversity orthogonal frequency division multiplex wireless communication systems. The steps include: transmitting long training symbols during a long training period. In the first channel, the specifications of the long training, training time & are in line with the "Media Access Control Layer and Physical Layer of the Wireless Local Area Network" formulated by the American Electronic Motors King Buying Association; During the training period, the long training symbol is transmitted on the second channel. During the period of ##, the transmission message is "expected on the-channel, and the specifications of the miscellaneous number period are in accordance with the regulations formulated by the Institute of Fine Electronic Ball Masters." The media access control layer and physical layer standards of the secret domain network are not transmitted; within the signal period, the signal data is transmitted on the second channel; during the data period, one of the long training symbols—the complex common secret element is transmitted. On the first channel; during the data period, transmitting the long scale symbol element-negative value complex number element to the second channel; «practical symbol element number complex number element and negative value number element conjugate symbol element; And the long training character received , The long training symbol complex conjugate of the symbol, and: cut 9179 ', Shu East pay 7C plurality of negative total light symbols, through the operation to obtain the channel characteristic value. 2. A method for estimating the characteristic value of a channel, the steps of which include:-transmitting a-symbol symbol to a-channel within a first period; transmitting the symbol symbol to a-second channel within the first period Channel; In the first period, 'transmitting' signal data is in the first channel; In the first period, transmitting a signal data in the second channel; In the second period, transmitting the Lai Jing symbol element-the miscellaneous symbol element During the first read through :; and in the third period, 'transmit the outline symbols—negative plural complex symbols to the first channel. 3. The method as described in item 2 of the scope of patent application, wherein the step of transmitting the training unit on the first channel in the first period includes: setting the long training packet in the header field before the 1-layer convergence program packet. The symbol is on the first channel. Transmitting • The method described in item 3 of the scope of patent application, further comprising: transmitting the training symbol to the first channel again during the long training period in the header block before the physical layer convergence program packet. . 5. The method as described in item 2 of the scope of patent application, wherein the steps of transmitting training I239ί79,.. .5 in the second channel in the first period, including the step of -_ before the entity purely touches the vehicle package During the long period in the file, the training symbol is transmitted to the second channel. 6. The method as described in item 5 of the scope of patent application, further comprising: transmitting the training symbol to the second channel again within the entity's purely concentrating packet packet _ block money seeking training period. 7. The method described in item 2 of the scope of patent application, the step of transmitting the complex conjugate symbol of the training symbol on the first channel in the third period, including ... During the period, the complex conjugate symbol of the training symbol is transmitted to the first channel. 8. The method according to item 2 of the patent application, wherein the step of transmitting the negative complex conjugate symbol of the training symbol to the second channel in the third period includes:-converging the program packet at a physical layer- During the data period, the negative complex conjugate symbol of the training symbol is transmitted to the second channel. 9. The method according to item 2 of the scope of patent application, further comprising: transmitting additional training symbols to the first channel during other periods. 10. The method according to item 9 of the scope of patent application, wherein the number of other periods is proportional to the number of transmission channels. • The method described in claim 2 of the patent scope, further comprising: transmitting additional training symbols to the second channel within ', other time, and again. 12 · —A method for estimating channel characteristic values, including: receiving a first-receiving, and the first-character element includes: training symbol 7G, transmitted to a first channel within a first period, and the training, east, and east Symbols 'are transmitted on the second channel during the first period; pure 4 遽 data, and the signal data are transmitted on the first channel during the second period' are fed on the second channel during the second period Receive-the m-th, and the second symbol includes: one of the training symbols is a complex number of symbols, transmitted to the first channel in the third period, and one of the training symbols is a negative complex number The yoke symbol is transmitted to the second channel in the third period; and the received first symbol and second symbol are used to estimate the channel characteristic value. 13. The method according to item 12 of the scope of patent application, wherein the step of estimating the channel characteristic value comprises: separating the first channel effect from the first symbol and the second symbol; and the first symbol In the element and the second symbol, the second channel effect is separated. ΓΙ239179 14. The method according to item 13 of the scope of patent application, further comprising: estimating the characteristic value of a first channel from the separated first channel effect; and the separated second channel effect from the separated first channel effect, Estimate the characteristic value of a second channel. 15. A system for estimating channel characteristic values, comprising: transmitting a training symbol to a transmission unit of a first channel in a first period; transmitting the training symbol to a second period in a first period; A transmission unit of the channel; a signal unit transmitting the signal data to the transmission unit of the first channel within a second period; a signal unit transmitting the signal data to the transmission unit of the second channel within the second period; and a third period Transmitting a complex conjugate symbol of one of the training symbols to the transmission unit of the first channel; and transmitting a negative complex conjugate symbol of one of the training symbols to the second channel during the third period; Transmission unit. 16. The system according to item 15 of the scope of the patent application, wherein the transmission unit transmitting the complex conjugate symbol of the training symbol to the first channel in the third period includes: one of the convergence program packets at a physical layer During the data period, the complex conjugate symbol of the training symbol is transmitted to the transmission unit of the first channel. 5 1239179 R The system described in item 15 of the scope of the patent application, which is transmitted in the third period and conveys the knowledge of the negative number of puppets in the third period. The scale elements in the second channel include. During a data period of the packet, the negative complex conjugate symbol of the training symbol is transmitted to the transmission unit of the second channel. 18. The system described in item 15 of the scope of patent application, further comprising: at other times, the ribs, objects, and objects transport a single-sided transmission unit. 19β A system for estimating channel characteristic values, including a receiving unit that receives a -th-symbol, and the first symbol includes:-a training symbol, which is transmitted on the _th channel in the _th period; and the The training symbol it is transmitted on the second channel in the first period. The first = Γ: unit_in-* second_ is transmitted on the second channel in the first period. Receive-the second symbol The receiving unit of the element, and the second symbol includes: Road: The transmission of the symbol element-the woman element is transmitted to the first communication platform side in the second period: the coffee is transmitted to the second value: the receipt Γ: The system described in the item 19 of the scope 'where-measuring channel characteristics 1239179 乂 the first element and the first symbol, separating the receiving unit of the first channel effect, and the first symbol and the second symbol, The receiving unit of the second channel effect is separated. 21. The system as described in item 20 of the scope of patent application, further comprising: a first channel effect derived from the powder, a receiving unit for estimating a characteristic value of the first channel; and a second channel effect derived from υ, A receiving unit for estimating a characteristic value of a second channel. A system according to item 15 of the scope of patent application, including a wireless device composed of the transmission early 70, the wireless device being a access point unit of a wireless local area network. 23-A method of estimating channel characteristic values, the steps of which include: transmitting a training symbol to the first channel during the -th period; transmitting the training symbol it to the second channel during the first period Transmitting the training symbol to the second channel again during the first period; transmitting a complex conjugate symbol of one of the training symbols to the first channel within the second period; and Second, a negative complex number of the training symbols is transmitted to the second channel. 24. The method as described in item 23 of the scope of patent application, wherein the step of transmitting training symbols on the first channel in the first period includes: "setting the header block before converging the program packet at a physical layer During the long training period, transmit the training symbol to the first channel. 25 1239179 • The method described in item 24 of the scope of patent application, further including: ▲ The guilin receives the package of the long touch towel During the period, the person again transmits the training symbol to the first channel. _ • The method as described in item 23 of the patent application scope, wherein the step of transmitting the training symbol to the second channel during the first period includes: · Sending the training symbol to the second channel during a long training period in the slot header field before a physical layer convergence program packet. 27. The method described in item 26 of the patent application scope further includes: Within the long training period in which the header block is placed before the physical layer convergence program packet, the training symbol is transmitted again on the second channel.