CN101778062B - A kind of method of the single carrier frequency domain equalization frame constructed under short wave communication channel - Google Patents
A kind of method of the single carrier frequency domain equalization frame constructed under short wave communication channel Download PDFInfo
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- CN101778062B CN101778062B CN200910243890.8A CN200910243890A CN101778062B CN 101778062 B CN101778062 B CN 101778062B CN 200910243890 A CN200910243890 A CN 200910243890A CN 101778062 B CN101778062 B CN 101778062B
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Abstract
The invention discloses a kind of for the single carrier frequency domain equalization frame structure under short wave communication channel, described frame structure comprises frame head and several time slots, and wherein, each described time slot comprises a leader block and several packets further.The present invention is directed to the single carrier frequency domain equalization frame structure under short wave communication channel, adaptive frequency domain equilibrium can be utilized to carry out equilibrium treatment, can reach good portfolio effect, and along with the increase of multi-path delay spread, complexity of equalization is compared time domain equalization and is greatly reduced.Compare parallel system, peak-to-average force ratio is low, and mitigating frequency-selective fading ability is strong, at identical conditions, can reach higher transmission rate and the lower error rate.
Description
Technical field
The present invention relates to New Technology Of Shortwave Communication field, particularly relate to for a kind of single carrier frequency domain equalization (Single Carrier Frequency Domain Equalization, the SC-FDE) frame structure under short wave communication channel.
Background technology
According to the division of Consultative Committee on International Radio (CCIR) CCIR (Consultative Committee of International Radio), shortwave refers to the electromagnetic wave of wavelength 100m ~ 10m (frequency is 3MHz ~ 30MHz).The radio communication that radiothermy carries out is called short wave communication.
The frequency range of the actual use of short wave communication is 1.5MHz ~ 30MHz, available frequency range only has 28.5MHz, and according to international regulations, each short-wave radio set takies the band width of 3.7kHz, communication space is very crowded, greatly limit the capacity of communication and the speed of transfer of data.
Short wave communication is all the form adopting sky-wave transmission, ionospheric one or many is namely relied on to reflect into Serial Communication, therefore there is serious multipath effect, statistics shows, multipath way is the highest with 3 occurrence probabilities, multidiameter representative value 2 ~ 8ms, becomes the main restriction of short-wave link transfer of data.
The sky wave channels could of shortwave is variable-parameter channel, and stable signal transmission is poor.Hf radio communication mainly relies on ionosphere and carries out distant signal transmission, and ionosphere as the weakness of signal reflex medium is, the changeability of parameter is very large.Its feature is path loss, time delay expansion, Noise and Interference, all with round the clock, frequency, place and constantly vary.Ionospheric change makes signal produce decline on the one hand, and amplitude and the frequency of decline constantly change.
In addition, air and wireless industrial electrical noise interference serious.Air and wireless industrial electrical noise mainly concentrate on the low side of radio-frequency spectrum, and along with the rising of frequency, intensity reduces gradually.Although low at this kind of noise interference of shortwave frequency range medium-long wave band, intensity is still very high, affects the reliability of short wave communication, especially impulse type burst noise, transfer of data often can be made to occur burst error, have a strong impact on communication quality.
, there are parallel and serial two kinds of systems in a new generation's Shortwave Communication System mainly high speed HF digital communication system.The main thought of parallel system is exactly short wave channel is divided into some parallel subchannels, transmits a subcarrier on each of the sub-channels, adopts frequency division quadrature modulation, improves speed, be also called multitone by the method for multiple subcarrier parallel transmission.Typical system has the realization means of French Thomson (Thomson) company, adopts OFDM (Frequency Division Multiplexing, OFDM) system, subcarrier number 79.
Serial system adopts the send mode of single carrier wave, because only adopting a carrier wave, also referred to as single-tone.Data modulate transmission in a serial fashion, and symbol width is short, reach higher speed, and as 2400bps, intersymbol interference will be very serious.Suitable balancing technique is adopted to resist intersymbol interference in reality.
There is following shortcoming in parallel system technology: transmitting power is disperseed, and signal peak-to-average ratio is large, and mitigating frequency-selective fading is poor, is difficult to the technology of the anti-intersymbol interference utilizing the serial systems such as decision feedback equalization to use.
There is following shortcoming in serial system technology: the serial system for short wave communication mostly adopts Time Domain Equalization techniques, and along with the raising of message transmission rate, when transmission bandwidth is more close to the coherence bandwidth of channel, time dispersive will be more serious.Now contain the multipath ripple of experience decay and time delay in Received signal strength, cause frequency selective fading, thus cause serious intersymbol interference.If alone time domain equalization alleviates intersymbol interference, need more filter tap just can obtain acceptable portfolio effect, be difficult to like this reach requirement of real-time, and along with the increase of multi-path delay spread, complexity of equalization even may increase by exponentially.
Summary of the invention
The invention provides a kind of for the single carrier frequency domain equalization frame structure under short wave communication channel, there is the parallel problem that system mitigating frequency-selective fading is poor, serial system complexity of equalization is high in order to solve in prior art.
For reaching above-mentioned purpose, the invention provides a kind of for the single carrier frequency domain equalization frame structure under short wave communication channel, described frame structure comprises frame head and several time slots, and wherein, each described time slot comprises a leader block and several packets further.
Wherein, it is the UW sequence of 8 and unloaded data that described frame head comprises Baud Length further, and wherein, UW sequence is several.
Wherein, described leader block comprises further: Baud Length is the Cyclic Prefix sequence of 32, two Baud Lengths be 64 UW sequence and Baud Length be 32 UW sequence.
Wherein, described packet comprises further: Baud Length be 224 data segment and Baud Length be 32 UW sequence.
Wherein, the duration of described frame head is 96ms.
Wherein, described frame head comprises the UW sequence that 18 Baud Lengths are 8.
Wherein, each described time slot comprises 11 packets.
Wherein, described frame head is used for input and frequency deviation estimation first.
Wherein, the leader block of each described time slot, estimates and channel estimating for timing estimation, frequency deviation.
Wherein, several packets of each described time slot, for realizing frequency domain equalization, frequency deviation tracking, timing tracking, channel tracking, decoding successively.
Beneficial effect of the present invention is as follows:
The present invention is directed to the single carrier frequency domain equalization frame structure under short wave communication channel, adaptive frequency domain equilibrium can be utilized to carry out equilibrium treatment, can reach good portfolio effect, and along with the increase of multi-path delay spread, complexity of equalization is compared time domain equalization and is greatly reduced.Compare parallel system, peak-to-average force ratio is low, and mitigating frequency-selective fading ability is strong, at identical conditions, can reach higher transmission rate and the lower error rate.
Accompanying drawing explanation
Fig. 1 is a kind of structural representation for the single carrier frequency domain equalization frame structure under short wave communication channel of the embodiment of the present invention;
Fig. 2 is the structural representation of a kind of time slot for the single carrier frequency domain equalization frame structure under short wave communication channel of the embodiment of the present invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, do not limit the present invention.
The present invention proposes the data frame structure being applicable to short wave communication based on single carrier frequency domain equalization (SC-FDE) technology and technical scheme.Single-carrier frequency domain equalization system is a kind of effectively method to anti-multipath jamming in broad band wireless transmission.Compare parallel system, peak-to-average force ratio is low, and mitigating frequency-selective fading ability is strong, can reach higher transmission rate and the lower error rate at identical conditions; Compare general serial system, complexity also reduces greatly, and is applicable to higher transmission rate.
SC-FDE technology sends signal with symbolic blocks structure, needs to insert Cyclic Prefix within the data block and carries out frequency domain equalization.SC-FDE system data transmits frame by frame, based on SC-FDE technology the frame structure being applicable to short wave communication as shown in Figure 1, the frame structure of every frame comprises frame head and N number of time slot, and each time slot is become with M data packet group by 1 leader block again.Wherein frame head comprises L UW sequence (Unique Word, unique word sequence, be generally chu sequence, frank-zadaff sequence, PN sequence that IEEE802.16a standard specifies) and unloaded data, the Baud Length of each UW sequence is 8 (being labeled as UW8 in figure).Fig. 2 is the structural representation of each time slot, as shown in the figure, the UW sequence (being labeled as UW64 in figure) that leader block comprises Cyclic Prefix (CP, the Cyclic Prefix) sequence of 32 Baud Lengths, two Baud Lengths are 64, Baud Length are the UW sequence (being labeled as UW32 in figure) of 32; Packet comprises the UW sequence (being labeled as UW32 in figure) that the data segment (being labeled as Data in figure) of 224 Baud Lengths and Baud Length are 32.Wherein CP is used for the Cyclic Prefix of UW64, and UW32 is used for the Cyclic Prefix of packet.
The frame structure of the present embodiment, frame head is used for input and frequency deviation estimation first; The leader block of each time slot is used for timing estimation, frequency deviation is estimated and channel estimating; In M packet of each time slot, realize frequency domain equalization, frequency deviation tracking, timing tracking, channel tracking, decoding successively.Frame is used for input, frequency deviation estimation first, timing estimation, frequency deviation estimation, channel estimating, frequency domain equalization, frequency deviation tracking, timing tracking, channel tracking and decoding, to be used for realizing above-mentioned functions identical with other Frame, can be realized by existing method, the present embodiment no longer describes in detail.
Due to the particularity of short wave communication, its maximum symbol transmission rate is generally 3kHz, and namely element duration is 1/3ms.Arranging frame head duration is 96ms, and L value is wherein 18, and the duration of such frame head is 8 × 1/3 × 18=48ms, enough for preamble detecting.Remaining 48ms duration not transmitting data, can be used for carrying out receiving terminal and returns the feedback of transmitting terminal.Consider that the maximum delay expansion of short wave channel is approximately 8ms simultaneously; the UW sequence that Cyclic Prefix is 32 Baud Lengths is set; the time delay protected of such Cyclic Prefix is 10.67ms (32/3ms), is greater than the maximum delay expansion 8ms of channel, can resists the impact that multipath brings.
The leader block duration of each time slot is (64 × 2+32 × 2)/3ms=64ms, packet in each time slot is set to 256 (224+32) individual Baud Length, each like this packet is approximately 256/3ms=85.33ms, setting data bag number M=11, each like this time slot is approximately 1s (85.33 × 11ms+64ms), because the Doppler shift of short wave channel is approximately 1Hz, namely 1s is approximately the coherence time of channel, therefore it is suitable in 1s, carrying out a channel estimating, the accurate of channel estimating can be ensured, the transmission rate of valid data can be ensured again.
Because in each preamble detecting process, unloaded data can carry out the feedback of receiving terminal to transmitting terminal, the number N of the time slot of every frame is set, determine the feedback passback that every N can carry out a receiving terminal second, feedback data can be used for realizing the functions such as the adaptively selected tranmitting frequency of transmitting terminal.
As can be seen from the above-described embodiment, the embodiment of the present invention utilizes adaptive frequency domain equilibrium to carry out equilibrium treatment, can reach good portfolio effect, and along with the increase of multi-path delay spread, complexity of equalization is compared time domain equalization and greatly reduced.Compare parallel system, peak-to-average force ratio is low, and mitigating frequency-selective fading ability is strong, at identical conditions, can reach higher transmission rate and the lower error rate.Follow the trail of in conjunction with frequency deviation in balancing procedure, timing is followed the trail of, channel tracking, can reach the effect being difficult to realization in parallel system.
Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (9)
1. construct a method for the single carrier frequency domain equalization frame under short wave communication channel, it is characterized in that, comprising:
Structure frame head and several time slots, and in each described time slot, be provided with a leader block and several packets;
Described frame head is used for input and frequency deviation estimation first;
Described leader block is used for timing estimation, frequency deviation is estimated and channel estimating;
Several described packets realize frequency domain equalization successively, frequency deviation is followed the trail of, regularly tracking, channel tracking and decoding;
Being provided with Baud Length in described frame head is the UW sequence of 8 and unloaded data, and wherein, UW sequence is several.
2. the method for claim 1, is characterized in that, is provided with in described leader block: Baud Length is the Cyclic Prefix sequence of 32, two Baud Lengths be 64 UW sequence and Baud Length be 32 UW sequence.
3. method as claimed in claim 2, is characterized in that, be provided with in described packet: Baud Length be 224 data segment and Baud Length be 32 UW sequence.
4. method as claimed in claim 3, it is characterized in that, the duration of described frame head is 96ms.
5. method as claimed in claim 4, it is characterized in that, described frame head comprises the UW sequence that 18 Baud Lengths are 8.
6. method as claimed in claim 5, it is characterized in that, each described time slot comprises 11 packets.
7. the method for claim 1, is characterized in that, described frame head is used for input and frequency deviation estimation first.
8. the method for claim 1, is characterized in that, the leader block of each described time slot, estimates and channel estimating for timing estimation, frequency deviation.
9. the method for claim 1, is characterized in that, several packets of each described time slot, for realizing frequency domain equalization, frequency deviation tracking, timing tracking, channel tracking, decoding successively.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102437906B (en) * | 2012-01-20 | 2013-12-04 | 中国科学院上海微系统与信息技术研究所 | Design method of HARQ (Hybrid Automatic Repeat-request) communication way applied to SC-FDE (Signal Carrier Frequency-Domain Equalization) baseband system |
| CN105049388B (en) * | 2015-07-05 | 2018-02-27 | 新华通讯社 | A kind of Shortwave Communication System and its transmission method based on fountain codes and single carrier frequency domain equalization |
| CN105119856B (en) * | 2015-07-14 | 2018-03-06 | 西安电子科技大学 | Single carrier frequency domain equalization method based on sub-block analysis |
| CN105162737A (en) * | 2015-09-11 | 2015-12-16 | 中国人民解放军国防科学技术大学 | Low-complexity self-adapting single carrier frequency domain equalization method and device for software radio system |
| CN111245755B (en) * | 2020-01-08 | 2022-09-13 | 中国船舶重工集团公司第七二四研究所 | Self-adaptive rate transmission method of low-complexity single carrier frequency domain equalization system |
| CN114302179A (en) * | 2022-03-09 | 2022-04-08 | 北京理工大学 | Video transmission method and device, electronic equipment and storage medium |
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| US7190681B1 (en) * | 1996-07-10 | 2007-03-13 | Wu William W | Error coding in asynchronous transfer mode, internet and satellites |
| CN101267419A (en) * | 2007-03-16 | 2008-09-17 | 富士通株式会社 | A time advance adjustment method and device for OFDM symbol timing |
| CN101414990A (en) * | 2008-12-02 | 2009-04-22 | 北京韦加航通科技有限责任公司 | Method for capturing carrier frequency bias and time delay of single carrier frequency domain equalizing system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7190681B1 (en) * | 1996-07-10 | 2007-03-13 | Wu William W | Error coding in asynchronous transfer mode, internet and satellites |
| CN101267419A (en) * | 2007-03-16 | 2008-09-17 | 富士通株式会社 | A time advance adjustment method and device for OFDM symbol timing |
| CN101414990A (en) * | 2008-12-02 | 2009-04-22 | 北京韦加航通科技有限责任公司 | Method for capturing carrier frequency bias and time delay of single carrier frequency domain equalizing system |
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