TWI244284B - Isotropic code division multiple access communication system - Google Patents

Abstract

This invention relates to an isotropic code division multiple access (CDMA) communication system, which comprises a transmitting device and a receiving device. The transmitting device is for transmission of user date signals, and comprises at least two direct sequence spreading modulators, at least two carrier modulators and a transmitting signal combiner. The receiving device is for reception of the combined signal from the transmitting device, and comprises at least two carrier demodulators, at least two direct sequence dispreading units as well as an output signal combiner. Each user in the CDMA system uses a flock of complete complementary codes as its signature code simultaneously to spread the user data signal at the transmitting device by direct sequence spreading and to despread the received signal at the receiving device, ensuring zero cross-correlation and zero out-of-phase auto-correlation at any possible relative time shift between any pair of user signature codes in both synchronous down-link channel and asynchronous up-link channel. Therefore, in this way, the CDMA communication system based on the invention can successfully remove all harmful multiple access interference (MAI) and multipath interference (MI) in order to greatly improve the quality of signal reception.

Description

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Second, the invention belongs to the present invention I. The present invention relates to a code division multiplex communication system. In other words, it relates to a two-way homogeneous code division multiplex communication system and method. Taxi, previous technology While the third-generation wireless communication system is about to enter the global deployment, the implementation architecture of the fourth-generation system has become one of the most common research topics in the communications industry. However, the efficiency of aiMnterface technology currently used in the third generation system should be further improved to meet the needs of the fourth generation system. At present, the most common problem is the ulMink of the second and third generation systems (such as IS_95, w_cdma, and Cdma2000) based on traditional CDMA technology. In a mobile communication system, "uplink" refers to the transmission from the mobile phone to the base station, and this part is usually far more vulnerable than the "downlink" (that is, the transmission from the base station to the mobile phone). Interference so as to affect performance. The up-chain channel is usually asynchronous and prone to many problems, thus becoming a weak point in the entire wireless transmission loop. 'Because the orthogonality between the user identification codes will completely disappear in the up-slot channel, resulting in a lower ratio than in the down-chain area. More severe Multiple Access Interference (MAI). This non-synchronous transmission characteristic in the uplink region also causes the data transmission speed of the uplink channel to be much lower than that of the downlink channel, thus limiting the total data throughput of the entire system. Due to the constant movement of mobile phone users in a cell and the change in the relative distance between different users and different base stations, the uplink chain of a mobile communication system must work in asynchronous transmission mode. The non-synchronous nature of the uplink channel makes it impossible for us to use ideal orthogonal codes when transmitting on the chain (such as Walsh- -6- This paper size applies to the Chinese National Standard (CNS) A4 specification (210 X 297 mm)

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1244284 A7 B7 V. Description of the invention (2)

Hadamard codes and OVSF codes, ... etc.). Therefore, non-ideal orthogonal codes (such as Gold codes and Kasami codes) are used in the uplink channels of the existing second and third generation systems, because non-ideal orthogonal codes will be better than ideal orthogonal codes in non-synchronous channels. More effective. However, the use of non-ideal orthogonal codes in the uplink channel alone cannot fundamentally solve the problem, because the cross-correlation characteristics between Gold codes or Kasami codes and codes in an asynchronous uplink channel are to be controlled. It is very difficult, sometimes because the cross-correlation value of the odd or even period that is unacceptably high is generated, the wireless transmission efficiency in this area will be greatly reduced. So far, in mobile communication systems based on traditional CDMA technology (such as IS-95, W-CDMA, and cdma2000), there is still no way to ensure that there is a "two-way homogeneity" in the synchronous downlink channel and the asynchronous uplink channel. (Isotropic) or similar uplink and downlink wireless transmission performance. First of all, because the amount of signal power in the uplink part is mainly determined by the mobile phone's lithium battery. And because users often make mobile phones indoors, it will greatly reduce the signal energy transmitted outdoors, that is, most of the signal energy emitted by mobile phones will be blocked indoors, and only a small part of the energy can be transmitted through the windows. Go outdoors to pass to the base station. Secondly, the difference in antenna height between the mobile phone and the base station also determines that it will be more susceptible to the effects of shielding, local scattering or transmission / penetration loss, etc. in the uplink channel. Third, because the data transmitted from the mobile phone to the base station in the same cell are not synchronized, some non-periodic cross-correlation functions between user identifiers, rather than periodic correlation functions, determine the chain. Part of the wireless transmission performance; unfortunately, the former is usually more difficult to control than the latter, which also leads to the application of the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 1244284 A7 than the paper standard of the downlink.

More serious multiple access interference problems in the channel. Therefore, it is necessary to provide an innovative and progressive multiplexing system to solve the above problems. The object of the present invention is to provide a two-way homogeneous code division multiplex communication system ', which includes: a transmitting device and a receiving device. The transmitting device is used for transmitting user's communication data. The transmitting device includes: at least two direct sequence spread spectrum modulators, at least two carrier frequency modulators and a transmitting signal synthesizer. ^ At least two direct sequence spread spectrum modulators include a first direct sequence spread spectrum modulator and a second direct sequence spread spectrum modulator. The first direct-sequence spread-spectrum alternator uses a first sub-code to spread the communication data to form a first spread-spectrum # number, and the second direct-sequence spread-spectrum modulator uses a second sub-code to the communication. The data spread spectrum forms a second spread spectrum signal, and the first subcode and the second subcode are complementary codes. The at least two carrier frequency modulators include a first carrier frequency modulator and a second carrier frequency modulator. The first carrier frequency modulator uses a first carrier frequency to modulate the first spread spectrum signal. The second carrier frequency modulator uses a second carrier frequency to modulate the second spread spectrum signal. The transmitting signal synthesizer is used for synthesizing the first spread spectrum signal having a first carrier frequency and the second spread spectrum signal having a second carrier frequency. The receiving device is used for receiving a composite signal of the transmitting device. The receiving device includes at least two carrier frequency demodulators, at least two direct sequence demodulators, and a received signal synthesizer. -8- This paper size applies to China National Standard (CNS) A4 (210X297 mm)

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1244284 A7-—- ________B7 V. Description of the invention () 4 7 f Two less carrier demodulators include H-wave demodulator and -2 carrier frequency demodulator. The first carrier frequency demodulator uses a first carrier frequency to demodulate the synthesized signal into a first spread spectrum signal, and the second carrier j frequency demodulator uses a second carrier frequency to demodulate the synthesized signal into the Second spread spectrum signal. * At least two self-directed sequence demodulators include a first-direct sequence demodulator and a first-direct sequence demultiplexer. The far-first-direct shore demodulator uses the first subcode to the first-spread spectrum signal. Demodulation, the second direct sequence demodulator uses the second subcode to demodulate the second spread spectrum signal. The received signal synthesizer is used to synthesize the demodulated first spread spectrum signal and the second spread spectrum signal to receive the communication signal of the user. Using the two-way homogeneous code division multiplex communication system of the present invention can have the characteristics of "two-way homogeneity without multiple access interference" and "two-way homogeneity without multiple path interference". The “two-way homogeneity without multiple access interference” means that the cross-correlation value between any two user codes at any relative time shift is zero in the uplink or downlink as well as in the synchronous or asynchronous channel. "Two-way homogeneity without multipath interference" means that the auto-correlation sub-peak value of any user code at any relative time shift is zero regardless of whether it is in the synchronous or non-synchronous channel of the uplink or downlink. Therefore, the two-way homogeneous code division multiplex communication system of the present invention can successfully eliminate all harmful multiple access interference and multipath interference, and greatly improve signal reception.口 口 Referring to FIG. 1, the two-way homogeneous code division multiplex communication system 10 of the present invention includes: a transmitting device 20, a multi-path channel 40, and a receiving device 30. · The launch

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The device 20 is used to transmit communication data of a plurality of users. As shown in the figure, the first user signal to the KK user signal. In order to simplify the description, KK = 2 in this embodiment indicates that there are currently two users. The transmitting device 20 includes a first user < spread spectrum and carrier modulator 21, a second user's spread spectrum and carrier modulator 22, and a transmit signal synthesizer 23. The first user's spread spectrum and carrier modulator 21 includes at least two direct sequence spread spectrum modulators and at least two carrier frequency modulators. As shown in the figure, the spread spectrum and carrier modulator 21 of the first user includes a first direct sequence spread spectrum modulator 211 of a first user, a first carrier frequency modulator 212 of a first user, a first A user's second direct sequence spread spectrum modulator 213 and a first user's second carrier frequency modulator 214. Similarly, M 2 in this embodiment. That is, the first direct-sequence spread spectrum modulator 2 1 1 of the first user makes use of the -number " -user's -sub-code C11 to spread the first user's communication data to form a first user's first Spread spectrum signal, the second user's second direct sequence spread spectrum modulator 213 uses a second sub code cu of a first user to spread the first user communication data to form a second user's second spread signal. The first sub-code cu of the -user and the second sub-code of the first user are not equal to one's complement. The first carrier frequency modulator 212 of the first user uses a first carrier frequency Π to modulate the first spread spectrum signal of the first user, and the second carrier frequency modulator 214 of the first user uses a second The carrier frequency f2 modulates the second spread spectrum signal of the first Z. Similarly, the spread spectrum and carrier modulator 22 of the second user includes at least two direct sequence spread spectrum modulators and at least two carrier frequency modulators. The second Zhang scale is applicable to @a 家 鲜 (CNS) 铁 格 (2iqχ297 公 董) Chuan ------------ 1244284 A7 B7 V. Description of the invention (6 households' spread spectrum and carrier modulator 22 includes a first direct sequence spread spectrum modulator 221 of a second user, a first carrier frequency modulator 222 of a second user, a second direct sequence spread spectrum modulator 223 of a second user, and a first The second carrier frequency modulator 224 of the two users. The first direct sequence spread spectrum fader 211 of the second user uses a first subcode C21 of the second user to spread the second user communication data to form a first The first spread spectrum signal of two users, the first direct sequence spread spectrum modulator of the second user 2 1 3 uses a second subcode C22 of the second user to spread the second user communication data to form a second The user's second spread spectrum number. The first subcode C11 of the second user and the second subcode C12 of the second user are complementary codes; and the complementary code with the first user constitutes the complementary code family. Two members. The first carrier frequency modulator 222 of the second user uses a first carrier frequency fl to modulate the frequency of the second user. A spread-spectrum signal, the first carrier frequency modulator 224 of the second user uses a second carrier frequency f2 to modulate the second spread-spectrum signal of the second user. The transmitting signal synthesizer 23 is configured to synthesize the first A first spread spectrum signal of a first user with a carrier frequency, a second spread spectrum signal of the first user with a second carrier frequency, a second spread spectrum signal of the second user with a first carrier frequency and the The second spreading number of the second user of the second carrier frequency is used to transmit a signal to the receiving device 30 via the multipath channel 40. The receiving device 30 is used to receive the first user number from the transmitting device 20 The receiving device 30 includes: at least two carrier frequency demodulators, at least two direct sequence demodulators, and a received signal synthesizer. As shown in the figure, the receiving device 30 includes: a first carrier of a first user Frequency demodulator 32, -11-

This paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm) 7 1244284 V. Description of the invention A first user first direct sequence demodulator 33, a first user _ carrier frequency demodulator 34. A second direct sequence demodulator 35 for a first user, a received signal synthesizer 36 and a decision device 37. W ° The synthesized signal from the transmitting device 20 first passes through a multiple rear channel 40. Then, the first carrier frequency demodulator 32 of the first user demodulates and converts the composite signal to the first user's first spread spectrum number 5. The second carrier frequency demodulator 34 of the first user uses a second carrier and pico frequency f2 to demodulate the synthesized signal into a second spread spectrum signal of the first user. The first direct sequence demodulator 3 3 of the first user uses the first subcode C11 of the first user to demodulate the first spread spectrum signal of the first user. The second direct sequence demodulator 35 of the first user uses the second subcode C 12 of the first user to demodulate the second spread spectrum signal of the first user. The received signal synthesizer 36 is used to synthesize the first spread spectrum signal and the second spread spectrum signal of the demodulated first user, and then pass the Decision Device 37 to perform soft judgment of communication data Or a hard decision, then the communication signal of the first user is obtained. Referring to FIG. 2 and FIG. 3, in order to illustrate how the two-way homogeneous code multiplexing communication system of the present invention can overcome the interference problem of multiple paths and multiple accesses by using the illustrated method, the simplest two-way homogeneous code multiplexing is multiplexed. The communication system is taken as an example. 'The spreading code used is: 匸 11 = (+ + +-), (^ 12 = (4 ·-+ +)' C21 = (+ +-+), C22 = (+ ---), which are complementary codes to each other. In this embodiment, we assume that K = M = 2, the first user uses C11 and C12, and the first user uses C 2 1, C 2 2 as the signature (signature c〇de), and it is assumed that the receiving device wants to detect the signal of the first user. The paper size is suitable for CNS A4 specification (21GX297 public-12-1244284) V. Description of the invention (Figures 2 and 3 show the In the two-way homogeneous code division multiplexing communication system of the present invention, the entire process of demodulation is performed using complementary codes (CC codes), and the interference problem of the heavy path is solved. Figure 2 illustrates the demodulation of The process of digits to ^ bits. Figure 3 illustrates the process of demodulating the first to third bits during upload. In order not to lose the generality ' Suppose that the first user's message is a continuous string of characters, whose value is {川 '⑴'⑴ 卜 ⑴' ... The name of the second user is mi'bl2'bl; 3} = {+ l '+ 1'_1}', and there are 2 paths (ie, the -path and the second path) in the transmission channel of each user signal, and the difference between the first path and the second path is 1 chip period (chip It can be easily seen from Figure 2 and Figure 3 that multipath interference will not affect the decoding result, even if only using a simple correlator to demodulate. As the delay value assumed above (_Slice periods) is just for convenience and discussion in the description, even if different delay values (for example: two or three slice periods) are used, the result will not affect the decoding result. Therefore, through the above-mentioned verification, the two-way homogeneous multiplexing communication system of the present invention can solve the problem of multipath interference. Moreover, it is not necessary to use a complex receiver in a conventional multiplexing communication system such as Rake. 4 and 5 to illustrate the two-way homogeneity of the present invention The code multiplex communication system does not have the problem of multiple access interference during the on-chain and off-chain. The chain is shown in Figure 4, so it is assumed that the signals of the first user and the second user are synchronized. The table is on the chain in Figure 5, so it is assumed that the The signal between one user and the second user differs by one chip, and the period is as long as the first subcode cu and the second subcode C12 of the first user are used to demodulate whether it is on-chain or down-chain. User communication information-13 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1244284 A7

It is completely unaffected by the second user. Similarly, if the first subcode C2 1 and the second subcode C22 of the second user are demodulated, the communication information of the first user can be obtained, and it is also completely unaffected by the first user. — Therefore, the two-way homogeneous code division multiplex communication system of the present invention provides a good air interface environment for the new generation of line communication, which can achieve no multi-channel and multiple access interference, thereby further increasing the capacity of the overall communication system. Toilet = material transfer speed. 〃 The bidirectional homogeneous code multiplexing communication system 10 of the present invention further includes a multi-path receiver (RAKE) to further improve the detection efficiency, and at the same time, maintain its excellent multi-path-free and multiple access interference characteristics. 6 and FIG. 7, it is shown that during uplink and downlink, a multi-path receiver (RAKE) of a two-path channel is used to demodulate a bit signal. Therefore, it can be known from Figs. 6 and 7 that the output of the receiving device 30 at this time will be doubled by using a simple matched filter ^, which is 16 (8 + 8, refer to Figs. 2 to 5 are 8). Referring to FIG. 8 to FIG. 10, the two-way homogeneous code division multiplex communication system of the present invention can provide more excellent characteristics than the conventional code division multiplex communication system. Among them, FIG. 8 shows the comparison of multiple access interference sensitivities in the upload channel between the two-way homogeneous code division multiplex communication system (cc / ds_CDMA) of the present invention and the conventional code division multiplex communication system (DS_CDMA). Among them, the conventional code division multiplex communication system uses Gold and Walsh codes (the lengths are 63 and 64, respectively). The two-way homogeneous code division multiplex communication system of the present invention uses a completely complementary code for direct sequence spread spectrum modulation. The subcode length is 16 and each user uses 4 subcodes for spread spectrum modulation. The system accommodates a total of four different users, each with a delay of 5 c h i p.

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Shows the two-way homogeneous code division multiplex communication system of the present invention and the conventional non-returning: the working mode (synchronization or synchronization) of the Tonglu system in the uploading and downloading channels affects the system bit error rate. Only awgn is considered Channel. Among them, the conventional multiplex communication system of knife code uses Goll and w code h (the lengths are 63 and 64 respectively). The two-way homogeneous multiplex communication system of the present invention uses full complementary codes for direct sequence exhibition. Frequency modulation, the length of its subcode is 16, each user uses 4 subcodes to spread the frequency modulation. The system can accommodate a total of four different users. In the upload channel, the delay between users is 5 chips. Figure 10 It shows that the two-way homogeneous code division multiplex communication system of the present invention and the conventional code division multiplex communication system of the present invention in the upload and download channels, the frequency selective attenuation of the channels existing in the channel to the bit error rate of the system. The path or four-path channel (composed of four equal-strength signals with a delay of 5 chips between paths) has the same normalized received power (in unit values). Among them, the conventional division code multiplex communication system uses G. ld and Walsh codes Are ^ and 64). The two-way homogeneous code division multiplex communication system of the present invention uses a completely complementary code for direct sequence spread spectrum modulation, and its subcode length is 16, and each user uses 4 subcodes for spread spectrum modulation. Receive The device uses the same gain combination (EGC) RAKE. In summary, the advantages of the bidirectional homogeneous code multiplexing communication system of the present invention are as follows: First, the bidirectional homogeneous code multiplexing communication system of the present invention does not need to use a RAKE receiver. To overcome the frequency selective attenuation in the channel. On the contrary, as long as a simple relevant receiving device can achieve good detection benefits, so the hardware cost of the receiver can be greatly reduced. Similarly, the double _____________________- 15 of the present invention: This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1244284 A7

In the process of signal detection, the receiving device of the homogeneous CDMA communication system does not need to estimate the channel information. In other words, in order to successfully achieve the maximum ratio combining (MRC) RAKE operation, the IRAKE receiver of the conventional code division multiplex communication system must obtain detailed channel information, such as the delay and amplitude of multipath reflections, thereby greatly improving The complexity of the phone hardware. Second point, as mentioned earlier, in order to obtain better detection performance, the present invention confuses the two-way homogeneous code multiplexing communication system to more effectively separate multipath reflections by using a conventional rake receiver to achieve its name. "Multipath diversity". Because the output of each branch in RAKE is only related to the peak value of the autocorrelation of a specific time parameter, the RAKE receiver is used in the two-way homogeneous multiplexing multiplexing communication system of the present invention relative to the conventional multiplexing multiplexing communication system. Can produce better signal detection results. In contrast, in a conventional multiplexed communication system, the output of each branch is a mixture of the useful part (the autocorrelation peak of the signal itself) and a large number of other unwanted components. The so-called unwanted components include the autocorrelation side peaks of their own multipath reflection signals and the cross-correlation main peaks and side peaks of other user multipath reflection signals. Therefore, due to the unique anti-frequency selective attenuation capability of the bidirectional homogeneous code multiplexing communication system of the present invention, it is particularly suitable for operation in channels with severe multipath interference. The second point is that in the two-way homogeneous code division multiplex communication system of the present invention, in essence, the signals of different users have undergone de-multiple access interference processing before transmission, or have undergone pre-correlation processing. . Therefore, the bidirectional homogeneous code division multiplex communication system architecture of the present invention has the characteristics of bidirectional homogeneity and no multiple access interference, making it unnecessary to use _-This paper standard is applicable to China National Standard (CNS) A4 specification (210X297 (Mm) 1244284 A7 ------------ B7_ V. Description of the invention (12) A multi-user detection technology to decorrelate the received signals (decorrelatmg). In other words, the signal design of the two-way homogeneous code multiplexing communication system of the present invention has long considered the multi-user signal decorrelation mechanism, so even if no complicated and error-prone multi-user detection algorithm is used, the two-way homogeneous code multiplexing of the present invention The signal detection performance of the receiving device of the communication system is still quite reliable. Fourth, in the relevant receiver of the two-way homogeneous code division multiplexing communication system of the present invention, if the bit synchronization can be guaranteed, due to its two-way homogeneity without multiple path interference, the near-far problem will not Damage to signal detection processing. In general, with the help of pilot signals, it is not difficult to achieve bit synchronization before data detection and processing. In other words, the bidirectional homogeneous code multiplexing communication system of the present invention is a system that has been carefully designed and has good near-far resistance. Therefore, the two-way homogeneous code division multiplex communication system of the present invention does not require a complicated accurate power control system. More precisely, the power control system of the two-way homogeneous code division multiplex communication system of the present invention is only used to reduce the power loss at the user end and unnecessary power transmission, so that the requirements for response time and accuracy of power control can be transmitted. It is looser than the conventional code division multiplex communication system. Fifth point: Due to the bidirectional homogeneity of the bidirectional homogeneous code multiplexing communication system of the present invention, the bidirectional homogeneity has no multiple access interference, so its operation is basically not affected by co-channel interference. Therefore, as long as the system does not require specific spatial information (such as the direction in which the received signal arrives), the signal processing advantages obtained by beamforming provided by smart antenna technology have been in the two-way homogeneous code division multiplex communication system of the present invention. The improvement in signal detection performance has little relevance. Therefore, the two-way homogeneous code division multiplexing of the present invention -17 · This paper size applies to China National Standard (CNS) A4 specification (210X297 mm) '' ------ 1244284 A7

The communication system does not necessarily need to adopt complex smart antenna technology to improve its signal detection performance. Summary 'The two-way homogeneous code division multiplex communication system architecture of the present invention, which is based on the two-way homogeneous access technology, can work in a non-interference operation due to its superior two-way homogeneity without multipath interference and multiple access interference characteristics. in environment. Using this nature, we can successfully transform an operating environment that is limited by interference into an operating environment that is limited only by noise. Therefore, the system capacity and data transmission rate can be greatly improved. Table i lists the main operational advantages of the bidirectional homogeneous multiplexed multiplex communication system architecture of the present invention and comparison with the conventional multiplexed multiplexed communication system. The above embodiments are only for explaining the principle of the present invention and its effects, but not for limiting the present invention. Therefore, those skilled in the art can modify and change the above embodiments without departing from the spirit of the present invention. The scope of rights of the present invention should be listed in the patent application scope mentioned later. L______ _-18- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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4 1244284 A7 B7 14 V. Description of the invention (Table 1, Comparison of CC / DS-CDMA and conventional DS-CDMA

CC / DS-CDMA DC-CDMA

Signal detection efficiency Multi-path diversity performance RAKE receiver anti-FSF + capability Near-far capability accurate power control multi-user detection uplink synchronization control smart antenna receiver hardware system capacity down-chain MAT up-chain MAI down-chain MΓ> MI Excellent (with or without RAKE) Excellent No need Excellent Excellent No need No need No need Simple Simple Low Low Low Low Medium ~ Good (Rake required) Medium No (no RAKE required) No need Advice Need Advice Need Advice Need complexity Low to medium low, 1 1 2 3, 1 1 combined ~ ^ ^ Middle, Middle and 1 FSF: Frequency-selective fading 2 ΜΑΙ: Multiple access interference 3 MI: Multipath Interference (multipath interference) 5. Brief description of the diagram FIG. 1 is a schematic structural diagram of a bidirectional homogeneous code multiplexing communication system according to the present invention; FIG. 2 illustrates the detection process of the present invention without multipath interference when the chain is down; FIG. 3 illustrates the present invention The detection process without multi-path interference when the chain is up; Figure 4 illustrates the detection process without multiple access interference when the invention is down chain; Figure 5 illustrates this The invention detects the detection process without multiple access interference when it is on the chain; Figure 6 illustrates the detection process where the RAKE receiver of the present invention has no multipath interference and multiple access interference when it is off the chain; Figure 7 illustrates the use of the RAKE receiver in the present invention. There is no multi-path when winding _-19- This paper size applies Chinese National Standard (CNS) A4 specifications (210 X 297 mm) 1244284 A7 B7 V. Description of the invention (15) Detection process of interference and multiple access interference; FIG. 8 shows a comparison of the sensitivity of multiple access interference in the upload channel between the two-way homogeneous code division multiplex communication system of the present invention and the conventional multiplexed code division multiplex communication system of the present invention; FIG. 9 shows the two-way homogeneous code division multiplex communication system of the present invention; The impact of the working mode (synchronous or non-synchronous) on the system bit error rate in the uploading and downloading channels of the conventional code division multiplex communication system; Figure 10 shows the two-way homogeneous code division multiplex communication system of the present invention and its application The impact of the frequency selective attenuation of the multiplexed communication system in the upload and download channels on the system's bit error rate. -20- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

Ι2Φ42 ^ 491135551 Patent Application Chinese Patent Application Replacement (August 1994) W 8 丨 1 _ A two-way homogeneous multiplexed multiplex communication system including: a transmitting device for transmitting user communication data, the The transmitting device includes: at least two direct sequence spread spectrum modulators, including a first direct sequence spread spectrum modulator and a second direct sequence spread spectrum modulator, the first direct sequence spread spectrum modulator uses a The first sub-code spreads a first spread signal to the communication material, and the second direct sequence spread-spectrum modulator uses a second sub-code to spread a second spread signal to the communication material. A subcode and a second subcode are complementary codes. At least two carrier frequency modulators have a first carrier frequency fader and a first carrier frequency modulator. The first carrier frequency modulator uses A first carrier frequency modulates the first spread spectrum signal, the second carrier frequency modulator modulates the second spread spectrum signal with a second carrier frequency; and a transmit signal synthesizer 'is used to synthesize the first spread spectrum signal. Carrier frequency The first spread spectrum signal and the second spread spectrum signal modulated by the second carrier frequency; a receiving device for receiving the composite signal of the transmitting device, the receiving device including: at least two carrier frequency demodulator Has a first carrier frequency demodulator and a first carrier frequency demodulator, the first carrier frequency demodulator uses the -th -carrier frequency demodulation to transform the synthesized signal into a first spread spectrum signal, and the first The two-carrier frequency demodulator uses a second carrier frequency to demodulate the composite signal into the second spread spectrum signal. 81050-940802.doc 1244284 At least two direct sequence demodulators having a first direct sequence demodulator and a second direct sequence demodulator, the first direct sequence solution # 1 generator uses the first subcode to the first spread spectrum signal. Demodulation, the second direct sequence demodulator uses the second subcode to demodulate the second spread spectrum signal; and a received signal synthesizer for synthesizing the demodulated first spread spectrum signal And a second spread spectrum signal. 2. If the two-way homogeneous code division multiplex communication system of item 丨 of the patent application scope, the child receiving device further includes a judgment device for soft or hard judgment of the communication signal, and then the user's transmitted communication signal is received. 3. If the two-way homogeneous code division multiplex communication system of item 丨 of the patent application scope includes a multi-path receiver, the multi-path receiver has a plurality of branches to obtain the communication signal in each of the carrier frequency channels. Multipath signal. 4. A transmitting device for a two-way homogeneous code division multiplex communication system for transmitting user communication data, the transmitting device includes: at least two direct sequence spread spectrum modulators with a first direct sequence spread spectrum 展And a second direct-sequence spread-spectrum modulator, the first direct-sequence spread-spectrum modulator uses a first subcode to spread the communication data to form a first spread-spectrum signal, and the second direct-sequence spread-spectrum The frequency modulator uses a first subcode to spread the communication data to form a second spread spectrum signal. The first subcode and the first subcode are complementary codes. At least two carrier frequency modulators have a The first carrier frequency modulator and a second carrier frequency modulator, the first carrier frequency modulator is 81050-940802.doc -2-repair (replace) the first carrier frequency modulation The first-spread-spectrum signal, the second carrier-frequency converter uses a second carrier frequency to modulate the second-spread-spectrum signal; and a transmit signal synthesizer for synthesizing the first-carrier frequency modulation -Spread spectrum signal and the second: carrier frequency modulation second Pilot signal. 5.- A receiving device for a two-way homogeneous code division multiplex communication system for receiving user communication data, the receiving device includes: at least two carrier frequency demodulators, having a first carrier frequency demodulator and A second carrier frequency demodulator, the first carrier frequency demodulator uses a first carrier frequency demodulation to transform the received communication signal into a first spread spectrum k number, and the second carrier frequency demodulator uses a The second carrier frequency demodulates the received communication signal into a second spread spectrum signal. At least two direct sequence demodulators have a first direct sequence demodulator and a second direct sequence demodulator. -The direct sequence demodulator uses the first subcode to demodulate the first spread spectrum signal, and the second direct sequence demodulator uses the second subcode to demodulate the second spread spectrum signal; and The received signal synthesizer is used for synthesizing the demodulated first spread spectrum signal and the second spread spectrum signal. 6. If the receiving device in the scope of patent application No. 5 further includes a judgment device for soft or hard judgment of the communication signal, the user can receive the transmitted communication signal. 81050-940802.doc • 3-