TW595151B - Carrier sensing, signal quality and link quality in a receiver - Google Patents

Abstract

In a receiver, two low-pass equivalent signal detection criterions when the timing, phase and amplitude of the received signal are known and unknown, respectively, are provided for the detection of the presence of a Barker sequence in a received signal by Neyman-Pearson hypothesis testing rule. In addition, signal quality and link quality to measure the current quality of environments for signal reception are provided by the employment of a differential decoder and a Viterbi decoder in the baseband receiver.

Description

595151 V. Description of the invention (l) Technical field to which the invention belongs The present invention relates to a wireless communication method and system of a factory, in particular to a carrier and signal quality applied to a baseband receiver of a wireless communication system And the link (11111〇 quality sensing method of the prior art wireless communication is widely used between separate electronic devices, for example, the second wireless area UlreleSS L〇Cal —k;

AN) is a secondary system with a dagger, which may be an extension or variation of a building's mid-line area network (LAN). In a wireless communication system, the transmission characteristics of a channel or a medium are important factors in the communication system. The medium will affect or distort the transmitted signal in different ways. For example, change the amplitude and / or phase of the frequency. As far as wireless communication is concerned, radio frequency (RF) technology has been well developed. For example, IEEE 8 0 2. 1 1 defines a standard for radio frequency systems to comply. :: # #The signal sent may be significantly affected by the radio frequency ☆ in the transmission of the medium in multiple paths (UuUiPath): mn "ight; l〇s) frequency-dependence of the signal received by the path . in action

Multi-path transmission may distort the received cheek ^ i, especially in the environment of the object between the transmitter and the receiver. Multi-path is due to multiple simultaneous :: 偟 on $ has hindered T ^ received signal

Page 5

595151 V. Description of the invention (2) ^ ~ The "from the transmitter is transmitted from a transmitter through a medium through a medium RF transmission", especially in indoor environments using wireless communication systems. A large number of multiple signal reflections occur. The reflection causes the signal to be blurred in time, for example, time dispersion (time-jamming), which has a great impact on the performance of the straightforward waVef0rm encoding system. 'Various path lengths lead to the signals being received The relative differences in delay, amplitude, and phase are combined approximately linearly at the receiver. Generally speaking, multiple paths are a frequency-dependent phenomenon, that is, their adverse effects change with frequency. The modulation method used to resist multiple path transmission is called spire ad spectrum. In a spread spectrum communication system, a bandwidth occupied by digital data is transmitted by a spreading signal in the transmitter. ) Or sequence (seqUence) multiplied by the digital signal to be extended or extended, the effect of the extension is amplified in the receiver Elimination of joint procedures (pr 〇cess 〇fc 〇rre 1 ati 〇η). Since multiple paths are frequency dependent, only part of the extended signal is significantly interfered. RF communication systems using spread spectrum technology are known and Widely used 'For example, WLAN products often use certain types of spread spectrum technology, such as direct sequence spread spectrum (DSSS) and freqUenCy hopping spread spectrum (FHSS)' Communication between mobile stations and access points (AP). One of the characteristics that distinguishes the spread spectrum technology is that the modulated output signal occupies a larger transmission frequency.

595151 V. Description of the invention (3) The bandwidth it occupies is greater than the required baseband information bandwidth. Conventional receivers use matched filters to improve the detection of spread spectrum signals. The matched filtering technique uses an optimized receiver filter, which has a frequency transfer function H * (f) that matches the frequency transfer function H (f) of the channel, where H * (f) is H (f) Conjugate complex numbers. Spread spectrum communications have been used in various applications, such as mobile phone communications, to provide robustness against jamming, good resistance to interference and multiple paths, and inherently confidential communications to prevent interception For example, in U.S. Patent No. 5,515,396 to 0816 Jean 07:21] 1. In US Patent No. 6,115,411 issued to van Driest, the time interval in a WLAN spread spectrum encoder is further loosened to increase the data rate in the communication system. Spreading sequence is a type of reference signal in radio frequency communication. It is known to be advantageous to transmit simultaneously a reference signal in a transmitter system along with the same information-bearing signal. In the receiver system, the reference signal has various uses, for example, to achieve baud and synchronization of the carrier and the transmitter system. The reference signal can also be used to determine the impulse response of the RF transmission (impu 1 se response). For example, U.S. Patent No. 5,748,677 to Kumar provides a method and system for transmitting and receiving changing reference signals simultaneously with a composite modulation data signal, which represents the source information bit information to reduce to a transmission wheel The power of the reference signal and improving the determination of the transmitted reference signal. On the other hand, WLAN is usually based on a medium access control (Medium

Page 7 595151 V. Description of the invention (4)

Access Control (MAC), which uses a listen-before-talk architecture, for example, Carrier Sense Multiple Access with Co 1 ii si 〇n Avoidance · CSMA / CA). For WLAN, the IEEE 802.11 standard is an industrial, scientific, and medical (industrial,

Scientific and Medical; ISM) standard for systems in the ISM band, which is a worldwide band and allows operating a spread spectrum system without a license. IEEE 802.11 is focused on the MAC and physical layer (PHY) protocols of access points based on networks and ad-hoc networks. It supports BPSK (DBPSK) and QPSK with differential coding. Direct sequence spread spectrum (DSSS), frequency hopping spread spectrum (FHSS) with Gaussian frequency key shift (GFSK), and infrared with pulse position modulation (Pulse Position M odu 1 ati η; Ρ Ρ Μ). In particular, under the IEEE 802.1.1b protocol, in order to indicate that the status of the medium is busy or headroom, a receiver should implement a Channel Clear Assessment (CCA) procedure. The CCA mechanism can be implemented by This is achieved by measuring the energy received in the medium and / or a specific signal pattern. For the architecture for measuring the energy received in the medium 'A technique was used to detect the start edge of the income packet and the energy received accumulated in a window of a certain length L, issued to the US patent of Boer et al. No. 5, 9 8 7, 0 3 3 provides an example of monitoring the received energy by a WLAN with an enhanced capture provision. There are several different spreading codes for other architectures that measure specific signal patterns in a medium.

595151

V. Description of the invention (5) The variation of (5) can be used, and the most significant one is called the maximal length sequence (m-sequence) extension signal (pseud ο η oise) or PN stone horse. One of the changes is to make

Gold codes used in the Global Positioning System ^ GPS, as well as Kasami codes and W a 1 sh codes used in the IS95 system. Codes and Fahrenheit codes are not exact extension codes, but they are also listed here for reference. In IEEE 8 0 2.1 1 b, the Barker sequence is a specific signal state of the CCA mechanism. Barker codes were originally developed for radar systems, and they are actually a PN code. The sub-set is a short code with a length of 1 to 3, which makes them commonly used in radar systems. The feature is the so-called one-shot association, not a smooth-end association. This function has 0 and − Side 1 obes, such as correlation coefficients, and in general this is not the case for p N codes. Figures 1 A and 1 B show a basic 7-bit Buck sequence or codeword [+++-+-] and auto-correlation on the basis of one-click, respectively, so that they are displayed in the center Peak and cross-correlation of 10 and -1. As shown in FIG. 1B, the example clock diagram provides an ideal correlator (corre 1 at 〇r) output, and the Barker sequence generates a spike and side peaks at a fixed level. However, FIG. 1 The small side peaks in B are only for reference. The size, shape and spacing of these side peaks are not intended to be proportional to the size. These side peaks are shown to illustrate that the correlator usually has some close to zero during the processing of the symbol (symb ο 1). A tiny output value.

595151 V. Description of the invention (6) In the related art, US Patent No. 5,184,135 issued to Par ad ise, US Patent No. 5,327,496 issued to Russell et al. 11 (US Patent No. 5,073,898 to 10 et al., U.S. Patent No. 5,4 7 1,4 9 7 to 26118 ¥, and U.S. Patent No. 5,371 to A 1 1 e η, 760 states transmission using the PN sequence. US Patent No. 5, 4 1 2, 6 2 0 issued to Cafarella et al. Uses a sequence of chips in a spread spectrum signal. US Patent No. awarded to Snel 1 5, 9 8 2, 8 0 7 discloses a high data rate spread spectrum transceiver that uses improved Fahrenheit codes to enhance overall system performance. Furthermore, US Patent No. 5,9 0 9 issued to Kamerman et al. 4 6 2 provides a system and method for improving a radio frequency receiver, which can be quickly trained with the preamb part of the data packet (preamb 1 e) to use the shortest preamble, and can be used under poor channel conditions. The transmitted signal is trained quickly and accurately. US Pat. No. 5, issued to Padovani et al. 5 3 5, 2 3 9, US Patent No. 5, 4 1 6, 7 9 7, issued to Gi lhousen, et al., US Patent No. 5, 3 0 9, 4 7 4 to Gi lhousen, et al., And US Patent No. 5,1 3,4 5 9 to Gilhousen discloses a CDMA spread spectrum mobile phone communication system using Fahrenheit spreading codes. US Patent No. 6, 2 1 9, 3 5 6 to Beukema describes a multiple path Multipath resistant wave form coding method 'It adds an extended chip code to an optimized set of waveforms to compensate for the expected time shift during transmission in the wireless channel and demodulation of the transmitted wave The chip code extension method can be used in BPSK, QPSK, and code architecture.

7. Description of the invention (7) __ There is a demand, value, and _ of the Barker sequence, and in addition, it can be detected in a single way in a channel or medium. It can be immediately adapted to the quality of each report signal and link, making it convenient for users. However, the environment of the automobile to enhance the quality of transmission and reception is' the conventional technology has not provided such quality services. SUMMARY OF THE INVENTION Accordingly, one of the objectives of the present invention is to disclose a method and system for measuring and detecting the carrier wave in a baseband receiver of a two-wire communication system. —The shape of the Mou Qishi loses A ”Man—Pearson's fictional test, the existence of the“ Buck sequence ”is determined by the use of a new rule. With the rule (Neyman-Pears〇n testing is not known and The amplitude, clock, and phase of the received signal are unknown. The standard of the catfish is to supply the sequence in a simple format. The comparison of the set threshold is broken, so the papaver is detected, which corresponds to : It was proposed 'to measure the difference of the signal and the link's quality and measure the quality of the signal and the link ViterbU (ViterbU decoding example is in Wu. 2 j quality is measured by monitoring the receiver: the cumulative phase = cumulative phase The difference is evaluated. By evaluating J's symbol 5 ^ 1 SUrV1Vlng) path and other paths combined (mer. Inch ratio decoding? F distance 'the link quality is provided. G 1 ng] to the most: f for The discussion received in the receiver system is based on the solution in Figure 2. At the transmitter end and baseband signal funding ^ bar, ° to '^ first modulated sequence g

Page 11 595151 V. Description of Invention (8) Process. An XOR gate 10 is used to combine the signals DATA and PN codes PRN 'from its input terminals 12 and 14, respectively, to generate a modulated signal 0υτ at its output terminal 16. In this embodiment, 'DA Τ is a binary code, and p R Ν is an 11-bit Barker code that complies with IEEE802.11b. A bit period TDATA of data is equal to 11 chip codes in the Barker code. The total period T p RN, the Barker code is composed of 11 chip codes, with the sequence "1 〇1 1 1 〇1 〇q 〇", where the rightmost chip code is the first to be output in time In a binary waveform coding, the waveform is formed from a sequence of N separate chip code values, each chip code has a value of 0 or 1, typically, the waveform sequence is a set of orthogonal sequences (Orthogonal sequences). There are several coding methods that can be used to map data bits (ma ρ) to wave patterns. Examples of these methods include binary phase shift (B inar y. Phase Shift Keying; BPSK), Quadrature PhaseShift Keying (QPSK) and Quaternary Binary Phase Shift Keying (QBPSK). Typically, the PN signal PRN is not related to the data source DATA to be transmitted Bit sequence and is stable St at i ο nary, that is, the order of the chip signal is the same for all symbol intervals (symb ο 1 intervals). The Barker code consists of 0 and 1 values (non-polar signals ) A sequence of chip codes is mutually exclusive with the information bit to be transmitted. A PN sequence is composed of multiple chip code signals. The polarity of these signals is a type of binary polynomial. Decision, so the chip signal is said to be modulated, however, the individual chip signal is not the PN signal, the complete sequence of the chip signal is. A complete Barker code sequence

Page 12 595151 V. Description of the invention (9) It is transmitted in the time period occupied by the symbols containing information. Therefore, if the symbol rate is 1 M Baud, 11 of the chips in the Buck sequence are exhausted. The chip code rate is 11MHz. By using the 11MHz chip rate signal to modulate the carrier instead of the original 1 MB B aud information signal, the spectrum occupied by the transmitted signal is increased by a factor of 11. Therefore, it is interpreted in the receiver. The response signal after reconciliation (c ore 1 ated) includes a series of sig η-inverted buck sequences to represent binary logic π 1 π information bits and non-inverted (ηοη— inverted) Barker sequence to represent binary logic π ″ information bits. The composite or modulated signal ουτ is then digitally-to-analog converter (Digital-to-Analog Converter;

D A C) is converted from a digital representation to an analog representation, transferred to a radio frequency band, amplified power, and transmitted by an antenna. Systems that transmit an unmodulated spread spectrum signal modulated with the same data to achieve synchronization and demodulation are known.

FIG. 3 shows a functional block diagram of an embodiment of a receiver system according to the present invention. In the receiver system, an antenna 20 is used to receive a radio frequency signal, which represents a data signal and a Barker sequence signal (that is, the entire composite signal). The received RF signal is first amplified in an RF tuner 22 and filtered by a band-pass filter to remove interference and noise outside the bandwidth of the entire composite signal being transmitted. Further processing, the received radio frequency signal is typically frequency-translated to a lower frequency, known as Intermediate Frequency (IF), in order to simplify the actual implementation, in some digital In the system, the F frequency is zero, which requires the rest of the procedures

595151 V. Description of the invention (ίο) 2 complex digital operations (real and imaginary parts) are implemented. The low-frequency signal from the output of the RF tuner 22 is an analog signal, which is further amplified by a power amplifier 24 and is further amplified by a power amplifier 24. An analog-to-digital converter (ADC) 26 converts from an analog representation to a digital representation. 1¾ The received and quantized signal is synchronized with the transmitter by the signal symbol frequency and carrier frequency. This synchronization also establishes the appropriate clock (ie, phase relationship). Demodulate the received composite signal. ADC 2 6 The sampling clock frequency is typically synchronized with the frequency of the signal symbol (ie, the inverse of the symbol interval) and is an integer multiple of the baud rate. For example, if the sampling rate of each ADC is the chip code rate Twice as much,

And the mother-A D C is 8-bits wide, then an ideal (perfectly received) non-inverted buck sequence will contain 22 8-bit ADC samples. The receiver 18 also has the function of Automatic Gain Control (AGC) 28. By transmitting an adjustment signal 30 to adjust the power gain of the amplifier 24, the energy of the received signal is maintained in subsequent procedures. Near-constant 'AGC is a control structure that eliminates channel gain changes at the front end of the demodulator, which may affect subsequent digital signal processing. The returned digital signal 3 2 is supplied to the carrier sensing 3 4. Timing acquisition (timingacquisiti ο η) 3 6 and the Viterbi decoder 40. The carrier sensing 3 4 receives the signal 32 and determines a carrier signal Arrival. In a communication system with matched filter associated demodulation, a decimal system called meteor addition (m e t r i c) is determined with respect to a finite interval called a sampling point. The phase synchronization of the transmitter and receiver symbol intervals ensures that the sampling points are established correctly. The clock capture 3 6 extracts the clock information X • and sends it to the Viterbi solution.

Page 14 595151 V. Description of the invention (11) Encoder 40, this clock captures 3 6 series of conventional techniques. — — The received digital baseband signal 32 is a —differential detector ⑼ :: ground = a signal quality SQ is used as a system performance parameter, for example; in order to decode and decode the waveform code modulation, it is connected to the MAC . The correlation is processed by the -correlator structure, and the waveform in the evaluation region ^ = normally represents an orthogonal or approximately positive. Since the base correlation will result in a low correlation value, ^ τ 2; * set mouth, all Relatively large correlation. The bit pattern corresponding to the ground waveform provided by the connection = w = Exception 'is used for the evaluation of the maximum correlation at _ = ^ = S. The shape of the fundamental frequency waveform is perfectly square; the information of the code is ::, but in practice, it will be-so that it does not interfere with other possible user skins in the frequency domain ::: + + the exception of transmission, It will output a large value. ] = In addition to the baseband signal becoming data, the Wittby calcite horse 40 is also ^ = :: However, the method of the present invention further generates a link quality LQ from the Witt j4〇 as system performance parameter. According to the present invention, in a wireless communication system, a row existing in a received signal is detected, for example, a signal received by a transceiver or a receiver in an e-port of a mobile station is modeled as a fabricated test problem ' And its performance depends on the statistics in the following. In particular, a method is proposed to indicate the existence of a sequence by the Newman-Pearson fiction test rule. The test rule is also called the maximum neighborhood binary decision. Rule (maximum likelihood binary decision rule) 595151 V. Description of the invention (12) It is the best solution under a restricted phase alarm probability PFA by maximizing the detection probability Pd. Generally speaking, a false The alarm is less severe than not detecting a packet at all 'The reason is that the receiver will try to synchronize to a non-existent packet after a false alarm, and will detect the first complete check of the received data. An error was detected. The transmitted and received low-pass equivalent signal model is provided under the assumption of additive white Nans noise (A dditive W hite G aussia η N 〇ise; AWGN) channel. Superimposed or added to the signal `` white 'noise has a power spectral density that is the same at all frequencies of interest' '' Gaussian 'means that the probability density function of the noise is Gaussian, the purpose of which is to Receive the sampling sequence to detect the presence of the Barker sequence. Let Equation 1 represent the signature wavef0rm composed of the Barker sequence. The support is [0, Fanchang, here). [〇Ue-i} is the sequence of the Barker sequence, and A) has the support. [〇A) Pulse shaping function. A pulse shaping function is used to provide the ability to sink the extra bandwidth beyond the theoretical minimum into the original signal spectrum. The received low-pass equivalent signal is

Page 16 595151 V. Description of the invention (13) s (t) = Rc {sl (t) e ^ t} [Formula 2] Here, 々⑴ is usually called the real-valued signal (rea 1 signa 1). ) Complex envelop, and is basically equivalent to a low signal. Because the real value signal has a frequency content concentrated in a narrow frequency band near the frequency 乂, it is called a band signal. In Equation 2, the received base frequency signal can be written as

[Formula 3] Here, when the Buck signal is present & ㈣, and when the Buck signal is not present, 0 = {〇}; P, 歹 and F are the magnitude, phase and timing of the received Buck signal; r = see is the symbol interval of the Buck signal; and zip (0 is the low-pass equivalent signal received, the power spectral density on both sides is from η. 1. Carrier sensing (1) when the received signal When the clock, phase, and amplitude are known, the detection criterion of the low-pass equivalent signal uses the 2 / & amp rate to sample the received signal ~ (0, sampled 595151. V. Description of the invention (14) The signal is mT-\-nTc + q- f ^ j9b {m-anA: x) d {n-) ^ c) p Here, if αΤ < ηΤ

Tc (gD: t〇 + z (m9n9g) Formula 4] If -βΤ0 < q ^ ~ T \ <-( β-1) Τ0 then z (m, ny q) = zLP (mT + nT + q —) 2 'is a sequence that is independent and equivalently distributed with a zero mean Gaussian random variable with a deviation value of ~. Without loss of universality and for ease of explanation, a rectangular pulse shaping function is considered, so the received sample is simplified as Equation 5] r {m9n, q)-pe ^ b (m-α ^) ά ^ η -) ^) + z (m9n9g) where, == O'lniV'c —1, and 7 = 〇, 1 〇 Therefore, the artificial test problem in detecting the Barker signal is:

Page 18 595151 V. Description of the invention (15) / 70: r {m, n > q) = z (m9n? Q)

Hx: rim.nq) = paj9b {m-an ^) d ((n-^) Nc) + z (m? N? G) [Formula 6] where "= ο ，] · ， " · ， # . -1 'And? =. Based on observations in a symbol interval, the neighborhood function is exp < i (factory) = Ν ^ \ 22 \ r (m, nyg)-peJ9b {m-) ά ^ ι-βχ? 2 = 0 5 = 0 exp l 0 J ^ J ^ \ r (mynyq) \ n = 0 $ * 02 ^ lr and according to the Newman-Pearson rule, the optimization test is X if then 4 ⑺ 2 < V, if: (r 2) 77 Λ if)) < 7 where 7 7 / is the designed critical value such that γ = Pr (z (r) > η \ Η ^ v Pr (i (r) = η \ Η ^)

[Formula 7] [Formula 8]

[Formula 9] 595151 V. Description of the invention (16) Here, γ is the designated value, which is the significant level of the test, and ν e [0,1] 〇 (2) when the clock of the received signal, When the phase and amplitude are unknown, the detection information of the low-pass equivalent signal is received. The previous information of the clock, phase, and amplitude of the Buck signal is not always known. However, when widely used in practical communication systems, At this time, AGC 2 8 provides previous information of the received amplitude, so it is left to a fictional test that takes into account the information of the clock and phase that were not received. When the received clock and phase are unknown, the simple artificial test problem in Equation 6 becomes a composite artificial test problem H0: r {m, n, q) ~ z {m > n, q): r (m9n9q ) =) d (^ n-fiq >,) Nc) + z (m, n9q) with [〇, magic and? ^ [〇, 7〇 [formula 1 0] neighborhood in this composite fictional test problem The function thus becomes

Page 20 595151 V. Explanation of the invention (17) [Formula 11] Here, P⑼ and outside) are the previous distribution functions of the random variables 3 and F, respectively. If it is a uniform sentence distribution, then formula 1 1 becomes L {r) k άτ

n = 0 qQ 丨 丨 Σ / 〇ΛΓ-1 J ^^ r (m? nyq) b (m · n = 0 ¢ = 0 h, Xt) [Equation 1 2] Here, the modified zero order Bessel (B esse 1) function, that is, j / \ _ 1 xcosff 0 In, and this second equation comes from the discrete-time nature of A and r on r. The test for the corresponding optimization of the received clock and phase information is 4 (factory): [Equation 1 3] rl if i (r)> 7 v if i (r) =?; 0 if Z㈠ < ?? Here, π is the critical value of the design, and V is a predefined random test factor of 0.

Page 21 595151 V. Description of the invention (18) In addition, due to the monotonic increasing characteristic of 4 (_), the optimization test can be approximated as [Formula 1 4] "1 if 2 (factory)"> 77 μif 2 (Factory) = ?? If 2 (factory) < ?? Here [Formula 1 5] That is, the neighborhood statistical value is the sum of the sizes of the received samples of the Buck association in a symbol interval. In Equation 15, the operation to get the Buck-related output size comes from the uncertainty of the received carrier phase, and the operation added on a symbol interval is used to average the unknown received clock. 2 Signal quality and link quality Both signal quality and link quality are measurements of the current environmental quality of signal reception. Since two decoders are used in the baseband receiver 18, that is, the difference shown in FIG. 3 Detector 3 8 and Viterbi decoder 4 0

Page 22 595151 V. Description of the invention (19) For two measurements named signal quality S Q and link quality L Q, corresponding to the reception quality of the differential detector 38 and the Viterbi decoder 40 respectively. (1) Signal quality In the proposed IEEE 8 0 2.1 lb baseband receiver 18, a differential detector 38 is used to generate a training sequence in the foreword to the channel estimator for training. A channel evaluator in a receiver to improve the receiver's receiving performance is known, such as impulse response training, however, the new system performance parameter SQ and the algorithms it uses are provided here by reference difference A block diagram of one embodiment of the detector 38 is shown in FIG. 4. Theoretically, the differential detector 38 determines the received information bit according to the accumulation of the phase difference between consecutive symbols. When the accumulated value is greater than 0, the decoded bit is set to 1, When the accumulated value is less than 0, the bit is set to 0. The quality of the differential detector 38 can be measured by the size of the accumulated value. A larger accumulated value implies a lower probability of decoding errors. The magnitude of the accumulated value is thus defined as the signal quality SQ in the baseband receiver 18. In other words, in FIG. 4, the sampled signal r (m, n, q) at the input terminal 42 is a combination of a series of delay units 44, a series of multiplication units 46, and an addition unit 48. And for dispread or pattern matching, the total number of the delay units 46 is 21, and the total number of the multiplication units 48 is 22. The sampling signal r (m, η, q) and each delay unit The output of 44 is multiplied by the individual chip code of the Barker sequence, as if the

Page 23 595151 V. Description of the invention (20) ---

The transmitted data is the same. After de-stretching, the output 50 of the addition unit 48 is squared by a square function 52 to generate a signal 54 for the clock capture 36 of FIG. 3. In addition, the de-stretching signal 50 is obtained by 22 The combination of the delay units 58, a yoke function, and a multiplication unit 60 that multiplies the output of the delay unit 5 8 by the conjugate despread signal is decoded differentially. The output 62 of the multiplication unit 60 further uses a real part function 64 takes out the actual part, an addition unit 68 accumulates the rounded out function 6 4 by adding round out 66 to the delayed accumulated signal 7 2, and the delayed accumulated signal 72 is The output of the adding unit 68 is generated by feedback to the adding unit 68 after a delay unit 70, which is reset by a reset signal 7 4 every 2 2 samples. The signal quality s Q is From the output of the delay unit 70, 'a decision unit 78 is used to generate a differential detection output 82'. Similarly, the decision unit 78 is activated every 22 samples to make a binary decision. (2) Link quality

On the other hand, when the channel bandwidth is close to the signal bandwidth, the extension will exceed a symbol interval and cause signal pulse overlap. In the D sss system 'if the channel bandwidth is close to the signal spectrum that has been stretched by a p N code', then the channel's spreading effect will exceed the period of one chip and cause chip code pulses to overlap. This bearer (pay 1 〇ad) The decoding is realized by a decision feedback Witby decoder 40, which effectively mitigates the Inter-Symbol Interference (ISI) and the chip code.

Page 24 595151 V. Description of the invention (21) Inter-Chip Interference (ICI). Therefore, another measurement is provided for the Viterbi decoder 40 in response to the quality of the bearer reception. In the Viterbi decoding, all paths are finally merged into a final state. Therefore, the distance between the paths merged to the final state determines the quality detected by the Viterbi decoder. In the baseband receiver 18, it is defined The minimum distance between the surviving path and other paths merged into the final state is taken as the link quality. As a result, it is convenient to report the quality of the signal and link, so that the user can adapt to the actual environment in real time to enhance the quality of transmission and reception. The above description of the preferred embodiments of the present invention is for the purpose of clarification, and is not intended to limit the present invention to exactly the disclosed form. Modifications or changes are possible based on the above teachings or learning from the embodiments of the present invention. The embodiments are selected and described in order to explain the principle of the present invention and allow those skilled in the art to use the present invention in practical applications in various embodiments. The technical idea of the present invention is intended to be covered by the following patent application scopes and their equivalents. Decide.

595151 Schematic description for those skilled in the art, from the following detailed description and accompanying drawings, the present invention will be more clearly understood, its above and other objectives and advantages will become It is more obvious, in which: Fig. 1 A and 1 B respectively show a 7-bit length Barker code and its autocorrelation function curve; Fig. 2 shows the modulation process of the baseband signal data and the Barker serial code at the transmitter end; Fig. 3 It is a functional block diagram of an embodiment of a receiver system according to the present invention; and FIG. 4 shows an embodiment of a differential detector for measuring signal quality. Description of drawings: 10 mutually exclusive or (XOR) gate 12 XOR gate 1 0 input terminal 14 XOR gate 10 input terminal 16 XOR gate 1 0 output terminal 18 receiver system 2 0 antenna 22 radio frequency tuner 24 Power amplifier 26 Analog-to-digital converter (ADC) 28 Automatic gain controller (AGC) 30 Conditioning signal 32 Recovered digital signal

Page 595151 Brief description of the diagram 34 Carrier detection 36 Clock capture 38 Differential detector 40 Viterbi decoder 42 Input of the differential detector 44 Delay unit 4 6 Multiplication unit 4 8 Addition unit 50 The output of the addition unit 48 5 The squared function 54 The output of the squared function 52 5 6 The total function 5 8 The delay unit 6 0 The multiplication unit 62 The output of the multiplication unit 60 6 4 The real part function 66 The output of the real part function 64 6 8 Addition Unit 7 0 Delay unit 72 Feedback from delay unit 70 7 4 Reset signal 7 8 Decision unit 82 Output of differential detector

Page 27

Claims (1)

595151 6. Scope of patent application 1. A method of carrier sensing, suitable for a receiver in a spread spectrum communication system, which uses a Barker sequence as the spread spectrum code / despread spectrum code, and is used in the transmitter The method performs spread-spectrum calculation on a data signal, and performs spread-spectrum calculation on a received signal at the receiver. The method includes the following steps: converting the received signal into a digital signal; detecting the digital signal according to a prepared test rule Whether to include the buck sequence; and to determine whether the carrier sensing result is the presence or absence of a carrier according to the detection result. 2 · If the method of the scope of patent application is No. 1, wherein the artificial test method is a Newman-Pearson artificial test method. 3. The method of item 2 in the scope of patent application, wherein the artificial test rule is a artificial test rule when the amplitude, clock and phase of the digital signal are known. 4. The method of item 2 in the scope of patent application, wherein the artificial test method is a artificial test method 1J when the amplitude of the digital signal is known but the clock and phase are unknown. 5 · A method for estimating signal quality, which is suitable for a receiver in a communication system and is used to calculate a signal quality value to reflect the signal quality status of a received signal. The signal modulation method used by the communication system is differential phase Modulation, the method includes the following steps: converting the received signal into a first digital signal; delaying the first digital signal to obtain a second digital signal; calculating a one between the first digital signal and the second digital signal difference 595151 6. Patent application phase angle value; accumulate the differential phase angle value to obtain an accumulated differential phase angle value; and generate the signal quality value according to the accumulated differential phase angle value. 6 · If the method of claim 5 of the scope of patent application, the method further includes performing a spread spectrum operation on the first digital signal. 7. The method according to item 6 of the patent application, wherein the differential phase angle value is an absolute value of a phase difference between the first digital signal and the second digital signal. 8. —A method for estimating link quality, applicable to a receiver in a communication system, for calculating a link quality value to reflect the signal transmission quality status of a communication link between a sender and a receiver, the receiving The decoder includes a Viterbi decoder for performing a Viterbi algorithm. By calculating the signal path length in a signal trellis, comparing the length of each possible signal path, and performing signal decoding processing based on the shortest signal path The method includes the following steps: converting a received signal into a digital signal; decoding the digital signal according to the Witby algorithm; and according to the length of the shortest signal path in the Witby algorithm and other signal paths. The length calculates this link quality value. 9 · The method according to item 8 in the scope of patent application, wherein the link quality value is the minimum value of the absolute difference between the shortest signal path length and other signal path lengths in the Witby algorithm. 10. The method according to item 9 of the scope of patent application further includes normalizing the quality value of the link. 1 1. A receiver in a spread spectrum communication system, which uses Page 29 595151 6. Patent scope: One Barker sequence is used as spread spectrum code / despread spectrum code. The receiver includes: an antenna to receive an analog radio signal; and a radio frequency tuner to convert the analog signal into A baseband analog signal; an analog-to-digital converter to convert the baseband analog signal into a digital signal; and a carrier sensing unit to detect whether the digital signal contains the Barker sequence in a digital test rule. 12. The receiver according to item 11 of the scope of patent application, wherein the proposed test method is a Newman-Pearson test method. 1 3 · If the receiver of the scope of patent application No. 12, wherein the artificial test method is a artificial test method in which the amplitude, clock and phase of the digital signal are known. 14. The receiver according to item 12 of the scope of patent application, wherein the artificial test method is a artificial test method in which the amplitude of the digital signal is known but the clock and phase are unknown. 15. A receiver in a wireless communication system. The communication system uses a differential phase modulation method to modulate a signal. The receiver includes: an antenna for receiving analog radio signals; and a radio frequency tuner for converting the signal. The analog signal becomes a baseband analog signal; an analog digital converter to convert the baseband analog signal into a first digital signal; and a signal quality estimation device for calculating a signal quality value to invert 595151 6. The scope of the patent application should receive the signal quality status of the signal. The signal quality estimation device includes: a delay unit to delay the first digital signal to obtain a second digital signal; a calculation unit to calculate the first digital A differential phase angle value between the signal and the second digital signal; and an accumulator to accumulate the differential phase angle value to obtain an accumulated differential phase angle value, and generate the signal quality value accordingly. 16. The receiver according to item 15 of the patent application scope further includes a despreading unit for despreading the first digital signal. 17. The receiver according to item 15 of the scope of patent application, wherein the differential phase angle value is an absolute value of a phase difference between the first digital signal and the second digital signal. 18. A receiver in a wireless communication system. The communication system uses a differential phase modulation method to modulate a signal. The receiver includes: an antenna for receiving analog radio signals; and a radio frequency tuner for converting the signal. The analog signal becomes a baseband analog signal; an analog digital converter to convert the baseband analog signal into a digital signal; a Viterbi decoder for performing a Witby algorithm and calculating a signal grid The length of the signal path in the figure, the length of each possible signal path is compared, and the signal path based on the shortest length signal is decoded; and a link quality estimation device is based on the shortest signal in the Viterbi algorithm. 595151 6. Scope of patent application The length of the number path and the length of other signal paths are used to calculate a link quality value. 19. The receiver of item 18 in the scope of patent application, wherein the quality value of the link is the minimum value of the absolute difference between the shortest signal path length and other signal path lengths in the Viterbi algorithm. 2 0. If the receiver in the 19th scope of the patent application, it further includes normalizing the link quality value. Page 32