CN1227993A - Frame structure suitable for wide-band code division multiple access signal transmission - Google Patents
Frame structure suitable for wide-band code division multiple access signal transmission Download PDFInfo
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- CN1227993A CN1227993A CN99100060A CN99100060A CN1227993A CN 1227993 A CN1227993 A CN 1227993A CN 99100060 A CN99100060 A CN 99100060A CN 99100060 A CN99100060 A CN 99100060A CN 1227993 A CN1227993 A CN 1227993A
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Abstract
A frame structure suitable for wide-band code division multiple access (CDMA) signal transmission features that a time-sharing multiplexing frame structure for dedicated physical control channel (CPCCH) and dedicated physical data channel (DPDCH) is used in forward link. Each frame is composed of 16 time slots, each being 0.625 ms. Each time slot contains pilot sign, function control sign, transmission speed indication and data. Several pilot signs are uniformly inserted in each time slot. In the condition of not adding the pilot signs, the frequency to insert pilot signs can be changed to make the frame structure more suitable for mobile channel and better track the variation in mobile channels, so effectively compensating the phase drift caused by the channel.
Description
The present invention relates to the method for channel estimating in a kind of digital mobile communication system and the frame structure of signal transmission, exactly, relate to the form of the signal transmission in broadband CDMA system and the method for coherent detection, the signal that belongs to digital mobile communication receives the field, is an important component part of digital receiver.
At present, code division multiple access (CDMA) successfully is applied in the second generation mobile communication system.IS-95 based on CDMA became American National Standard in 1993, obtain approval afterwards in the All Around The World scope, became international standard.Second generation mobile communication system based on CDMA has millions of business users in the whole world now.Many in the world countries all are being devoted to 3-G (Generation Three mobile communication system).Because many advantages of wideband CDMA (Wideband CDMA) system, WCDMA system most possibly become the access mode that 3-G (Generation Three mobile communication system) adopts.Japan, Europe, the U.S. etc. seem very active in the research of broadband CDMA communication system, they have proposed the standard of the 3-G (Generation Three mobile communication system) of oneself now.
In Europe and the Japanese wideband CDMA system that is proposed, all adopted the auxiliary coherent receiver structure of frequency pilot sign at the uplink and downlink link.Promptly in Frame, periodically insert frequency pilot sign, utilize these frequency pilot signs that periodically insert to form a logic pilot channel, under the situation that does not increase physical channel, channel parameter is estimated, realize the coherent demodulation of data-signal, thereby improve systematic function.
In the WCDMA system, the frame structure of forward link as shown in Figure 1.Adopted Dedicated Physical Control Channel (DPCCH) and the time-multiplexed frame structure of Dedicated Physical Data Channel (DPDCH) in forward link, every frame is made of 16 time slots, comprises frequency pilot sign in each time slot again, power control symbol, transmission rate indication and data.Form superframe by 72 continuous frames.
Referring to Fig. 1, every frame has 16 time slots, and every time slot is 0.625 millisecond, and the front end of each time slot is inserted with several frequency pilot signs P, and its number is N (referring to Fig. 2).The signal that receives in the pilot frequency symbol position utilization comes the channel fading at estimating pilot frequency symbol place, then the pilot signal of being received is averaged, thereby obtains estimating channel corresponding to the frequency pilot sign position intermediate.For data division, for realizing coherent demodulation, also must estimate its phase deviation, in the method in current Japan and Europe, they have adopted following dual mode to realize the coherent demodulation of data-signal:
(1) utilize the evaluation phase that obtains at pilot frequency symbol position, the mode of employing linear interpolation obtains the phase drift corresponding to data division, thereby realizes the coherent demodulation of data-signal.
(2) utilize the frequency pilot sign channel guess value in the adjacent a plurality of time slots in front and back to be weighted, and, realize the coherent demodulation of data division the phase drift of the weighted value that obtains as data-signal part correspondence.
The auxiliary relevant demodulation method of the frequency pilot sign that Japan proposes is just estimated once in 0.625 millisecond, does not catch up with the speed of channel fading, will make the phase estimation inaccuracy of data division like this, and systematic function descends.Fig. 2 has provided the signal transmission frame-form in Japan and European proposal, and wherein several information symbols of front are pilot signal symbols, represent with P, the back be data symbol, represent with data.Wherein a kind of typical numerical value is, the number of frequency pilot sign is 4, and the number of data symbol is 36, that is to say that the amount of information that frequency pilot sign takies is 10%.
Because the insertion of frequency pilot sign and the error of channel guess value between desirable coherent demodulation and the auxiliary coherent demodulation of frequency pilot sign, certainly exist certain performance difference, and the inevitable number with the frequency pilot sign insertion of this performance difference are relevant.
The purpose of this invention is to provide a kind of frame structure that is applicable to the wide-band code division multiple access signal transmission, a kind of problem that solves frequency pilot sign insertion frequency in the structure of time slot just is provided, transmits frame structure thereby propose a kind of signal that is more suitable in the high-speed mobile environment.
The object of the present invention is achieved like this: it is to have adopted Dedicated Physical Control Channel (DPCCH) and the time-multiplexed frame structure of Dedicated Physical Data Channel (DPDCH) in forward link, every frame is made of 16 time slots, each time slot is 0.625 millisecond, comprising frequency pilot sign, power control symbol, transmission rate indication and data are arranged, it is characterized in that: in each time slot, evenly disperse to be inserted with several frequency pilot signs.Frequency pilot sign is evenly spread in each time slot, under the situation that does not increase the frequency pilot sign number, changed the frequency that frequency pilot sign inserts, be more suitable for mobile channel, can follow the tracks of the variation of mobile channel better, more effectively compensation is because the phase drift that channel causes.
Can evenly disperse to be inserted with 3 frequency pilot signs in each time slot, each frequency pilot sign is made up of 2 bits, corresponds to I road signal and Q road signal respectively.
This frame structure also goes in the reverse link.
This frame structure also goes in the transformat of a certain road signal of transmission control signal in the I/Q multiplex mode.
Under certain data rate, the number of the frequency pilot sign of this frame structure should remain unchanged with the ratio of the number of corresponding data symbol.
Main thought of the present invention is in frequency pilot sign mean allocation to a time slot, thereby makes reduce the blanking time of channel estimating, and the variation of easier tracking channel that is to say, frequency pilot sign is distributed in the time slot, estimates channel better.Realize the mobile communication system channel fading at the frequency pilot sign that this utilization is distributed in each time slot, it mainly is the Doppler frequency shift that the relative motion owing to Receiver And Transmitter causes, because the Doppler frequency shift that is produced can cause the variation of signal phase, in the present invention, in case after the frame synchronization, the position of frequency pilot sign is known, and receiving-transmitting sides can be determined the state of frequency pilot sign simultaneously, utilize the frequency pilot sign that receives to determine like this because the channel phase drift that channel fading causes, utilize the phase drift of frequency pilot sign position to come the phase drift of specified data signal then, thereby realize the coherent demodulation of data-signal.
In addition, in the present invention who is proposed, behind the channel fading that estimates the pilot frequency symbol position place, also can adopt the channel fading at a plurality of pilot frequency symbol positions of weighting place to obtain the phase drift of data-signal, that is to say, the channel estimation value that a plurality of frequency pilot signs of adjacent a plurality of time slots are obtained is weighted, and the value that obtains at last is as the channel fading of data-signal, thus the coherent demodulation of realization data-signal part.
Frame structure of the present invention mainly be in the digital mobile communication since receiver constantly move, can produce Doppler frequency shift, if the speed of a motor vehicle is too high, can make Doppler frequency shift become big, and the method before adopting just occurs the fast inadequately problem of tracking velocity, and make the performance of the auxiliary coherent demodulation of frequency pilot sign descend greatly, can not realize its intended purposes.
Further specifically introduce the present invention below in conjunction with accompanying drawing and l-G simulation test chart:
Fig. 1 is a forward link frame structure schematic diagram in the broadband CDMA system.
Fig. 2 is the structure of time slot schematic diagram in the forward link frame structure in the broadband CDMA system.
Fig. 3 is each the structure of time slot schematic diagram among the present invention.
Fig. 4 be among the present invention signal at the schematic diagram of channel mode.
Fig. 5 is a theoretical analysis result schematic diagram of the present invention.
Fig. 6 is the structure of time slot schematic diagram of day this programme.
Fig. 7 is the structure of time slot schematic diagram among the present invention.
Fig. 8 is the present invention under the different business speed and the comparison diagram of traditional scheme.
Fig. 9 is the comparison diagram of the present invention and traditional scheme under different vehicle speed condition.
The present invention is a kind of frame structure that is applicable to the wide-band code division multiple access signal transmission, it is that frequency pilot sign is evenly spread in each time slot, under the situation that does not increase the frequency pilot sign number, changed the frequency that frequency pilot sign inserts, be more suitable for mobile channel, can follow the tracks of the variation of mobile channel better, more effectively compensation is because the phase drift that channel causes.Introduce the method for a kind of specific implementation of the present invention below:
Referring to shown in Figure 3, be inserted with 3 frequency pilot sign P in each time slot in the frame structure of the present invention, each frequency pilot sign P is made up of 2 bits, correspond to I road signal and Q road signal respectively, the frequency pilot sign that in each time slot, contains 6 bits like this, utilize current frequency pilot sign and Next frequency pilot sign to realize channel estimating, and the channel fading that data-signal experienced between two frequency pilot signs estimated, so the number of pilot symbols that the estimation of data-signal is adopted in the time slot is 4 (first frequency pilot signs that comprise a back time slot.Because used the QPSK modulation, so contain 8 pilot bits), carry out QPSK like this and be behind the serial to parallel conversion in the signal on I road and Q road, all comprising pilot bits.The structure of time slot of signal as shown in Figure 3.
The signal transmission form that carries out QPSK modulation back channel that is to say as shown in Figure 4, frequency pilot sign and data message through behind the serial to parallel conversion as shown in Figure 4.
Aspect channel estimating, can utilize frequency pilot sign to determine the channel fading situation, utilize the method for linear interpolation to obtain the phase drift of data division then, thereby realize the coherent demodulation of data-signal part.Conjugate multiplication received signal and estimated channel decline in order to overcome the channel fading drift, realizes the coherent demodulation that frequency pilot sign is auxiliary.
The present invention equally also can be applied in the reverse link.
In some mobile communication system, in link, might use the multiplexing mode of I/Q, at this moment might be therein a road in transmit frequency pilot sign and other control informations, data signal in other one tunnel, the same control signal that transmits of utilizing is carried out channel estimating, and the channel fading that data division utilization estimation obtains is realized coherent demodulation.Under this kind situation, for certain the road signal that transmits control signal, the structure of time slot that the insertion frequency of its frequency pilot sign promptly transmits also can be realized according to the present invention.
The present invention can also be applied to following situation: under certain data rate, according to the present invention, the ratio of the number of frequency pilot sign and data symbol number is a definite value, when data symbol increases, the number of corresponding frequency pilot sign also will increase, but can keep the constant rate of itself and data symbol.
The generation of frequency pilot sign can be adopted a pseudo-random sequence generator among the present invention, like this as long as the state consistency of receiving-transmitting sides pseudo-random sequence generator, that is to say that receiving-transmitting sides is synchronous, receiving-transmitting sides just can be determined the next state of frequency pilot sign simultaneously, thereby further strengthens the randomness that signal transmits.
Certainly, implementation method can be flexible more in the system of reality.
Superiority of the present invention can be found out clearly by following Simulation results:
Can find by theory analysis, when mobile station speed is higher, if consider because the dual decline that frequency pilot sign inserts and channel estimating is brought will be found if the frequency that frequency pilot sign inserts is not high enough, will make that decline is bigger, can not reach the purpose of the auxiliary coherent demodulation of frequency pilot sign.Result of theoretic analysis as shown in Figure 5, Fig. 5 is based on the carrier frequency of 1900MHz, abscissa NUMBER represents that frequency pilot sign inserts the number of data symbol afterwards among the figure, also expressed simultaneously the frequency that frequency pilot sign inserts, ordinate LOSS represents the decline between desirable coherent demodulation and the auxiliary coherent demodulation of frequency pilot sign.As can be seen from Figure, consider the accuracy of information efficiency and channel estimating, exist a frequency pilot sign to insert the optimum of frequency.
The present invention compares with the time slot format of day this programme: for the business of 64 kilobits per seconds, every time slot is 40 bits, and supposing to have 6 bits is frequency pilot signs, and then expense is 15%.Japan WCDMA suggestion in, the time slot format of general service channel as shown in Figure 6, each time slot front is the frequency pilot sign Pilot of 6 bits, the back is the data symbol DATA of 34 bits, forms a frame by 16 time slots.
Time slot format among the present invention as shown in Figure 7, wherein P represents frequency pilot sign, has three groups of frequency pilot signs, every group can be made of 2 bits, be dispersed in the time slot.DATA is a data symbol, has 34 bits.Form a frame by 16 time slots equally.
Day this programme and the performance comparison simulation curve of the present invention under different business speed have been shown among Fig. 8, ordinate BER among the figure represents bit error rate, abscissa is represented information rate, and its unit is KBPS, and the simulated environment of Fig. 8 is that 36 kilometers/hour changes of speed of a motor vehicle service rate obtains.Curve 1 among the figure is day this programme, and curve 2 is of the present invention.
It is under the situation of 64 kilobits per seconds that Fig. 9 shows at data rate, a present invention and day pairing characteristic curve of error code of this programme under the different mobile station speeds, ordinate BER among the figure represents bit error rate, and abscissa is represented the speed of travelling carriage, and its unit is metre per second (m/s) (m/s).Curve 3 among the figure is day this programme, and curve 4 is of the present invention.As seen from Figure 9, when the speed of a motor vehicle increased slightly to some extent, neoteric performance promptly was better than traditional scheme.
Be not difficult to find out that by simulation result performance of the present invention is better than existing program, especially when mobile station speed was higher, the present invention more had superiority.
Claims (5)
1. frame structure that is applicable to wide-band code division multiple access signal transmission, it is to have adopted Dedicated Physical Control Channel (DPCCH) and the time-multiplexed frame structure of Dedicated Physical Data Channel (DPDCH) in forward link, every frame is made of 16 time slots, each time slot is 0.625 millisecond, comprising frequency pilot sign, power control symbol, transmission rate indication and data are arranged, it is characterized in that: in each time slot, evenly disperse to be inserted with several frequency pilot signs.
2. the frame structure that is applicable to the wide-band code division multiple access signal transmission as claimed in claim 1, it is characterized in that: in each time slot, can evenly disperse to be inserted with 3 frequency pilot signs, each frequency pilot sign is made up of 2 bits, corresponds to I road signal and Q road signal respectively.
3. the frame structure that is applicable to the wide-band code division multiple access signal transmission as claimed in claim 1, it is characterized in that: this frame structure also goes in the reverse link.
4. the frame structure that is applicable to the wide-band code division multiple access signal transmission as claimed in claim 1 is characterized in that: this frame structure also goes in the transformat of a certain road signal of transmission control signal in the I/Q multiplex mode.
5. the frame structure that is applicable to wide-band code division multiple access signal transmission as claimed in claim 1 is characterized in that: under certain data rate, the number of the frequency pilot sign of this frame structure should remain unchanged with the ratio of the number of corresponding data symbol.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99100060A CN1081416C (en) | 1999-01-04 | 1999-01-04 | Frame structure suitable for wide-band code division multiple access signal transmission |
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| Application Number | Priority Date | Filing Date | Title |
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| CN99100060A CN1081416C (en) | 1999-01-04 | 1999-01-04 | Frame structure suitable for wide-band code division multiple access signal transmission |
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| CN1227993A true CN1227993A (en) | 1999-09-08 |
| CN1081416C CN1081416C (en) | 2002-03-20 |
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| CN99100060A Expired - Fee Related CN1081416C (en) | 1999-01-04 | 1999-01-04 | Frame structure suitable for wide-band code division multiple access signal transmission |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001011793A1 (en) * | 1999-08-09 | 2001-02-15 | Huawei Technologies Co., Ltd | A pilot synchronous channel structure for mobile communication systems |
| CN1859056B (en) * | 2005-10-25 | 2010-05-05 | 华为技术有限公司 | Method and device for optimizing pilot frequency in honey comb communication system |
| CN101292471B (en) * | 2005-07-27 | 2010-12-22 | 高通股份有限公司 | System and method for a forward link only physical layer |
| WO2010148945A1 (en) * | 2009-06-22 | 2010-12-29 | 华为技术有限公司 | Method and device for sending uplink data |
| WO2011009375A1 (en) * | 2009-07-22 | 2011-01-27 | 华为技术有限公司 | Method and user equipment for transmitting precoding control indication information |
| CN101523970B (en) * | 2006-08-22 | 2012-01-11 | 株式会社Ntt都科摩 | Radio base station used in mobile communication system |
| CN101061648B (en) * | 2004-11-19 | 2012-09-26 | 株式会社Ntt都科摩 | Mobile communication method and mobile station |
| CN106685877A (en) * | 2014-03-28 | 2017-05-17 | 上海数字电视国家工程研究中心有限公司 | Processing method of received signals of receiving end |
| CN114070383A (en) * | 2021-11-18 | 2022-02-18 | 东方红卫星移动通信有限公司 | Communication method and device for improving spectrum efficiency in low-orbit satellite communication system |
-
1999
- 1999-01-04 CN CN99100060A patent/CN1081416C/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001011793A1 (en) * | 1999-08-09 | 2001-02-15 | Huawei Technologies Co., Ltd | A pilot synchronous channel structure for mobile communication systems |
| US6965633B2 (en) | 1999-08-09 | 2005-11-15 | Huawei Technologies Co. Ltd. | Pilot synchronization channel structure for CDMA mobile communication system |
| CN101061648B (en) * | 2004-11-19 | 2012-09-26 | 株式会社Ntt都科摩 | Mobile communication method and mobile station |
| CN101292471B (en) * | 2005-07-27 | 2010-12-22 | 高通股份有限公司 | System and method for a forward link only physical layer |
| CN1859056B (en) * | 2005-10-25 | 2010-05-05 | 华为技术有限公司 | Method and device for optimizing pilot frequency in honey comb communication system |
| CN101523970B (en) * | 2006-08-22 | 2012-01-11 | 株式会社Ntt都科摩 | Radio base station used in mobile communication system |
| WO2010148945A1 (en) * | 2009-06-22 | 2010-12-29 | 华为技术有限公司 | Method and device for sending uplink data |
| WO2011009375A1 (en) * | 2009-07-22 | 2011-01-27 | 华为技术有限公司 | Method and user equipment for transmitting precoding control indication information |
| CN101964675A (en) * | 2009-07-22 | 2011-02-02 | 华为技术有限公司 | Method for transmitting precoding control instruction (PCI) information and user equipment (UE) |
| CN106685877A (en) * | 2014-03-28 | 2017-05-17 | 上海数字电视国家工程研究中心有限公司 | Processing method of received signals of receiving end |
| CN114070383A (en) * | 2021-11-18 | 2022-02-18 | 东方红卫星移动通信有限公司 | Communication method and device for improving spectrum efficiency in low-orbit satellite communication system |
| CN114070383B (en) * | 2021-11-18 | 2023-06-27 | 东方红卫星移动通信有限公司 | Communication method and device for improving spectrum efficiency in low-orbit satellite communication system |
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| CN1081416C (en) | 2002-03-20 |
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