CN102571660B

CN102571660B - In a communications system based on the continuous OFDM method and apparatus in N rank of RT

Info

Publication number: CN102571660B
Application number: CN201010600915.8A
Authority: CN
Inventors: 梁其辉; 肖悦; 刘辰; 薛梅; 黄若愚; 李品; 李少谦
Original assignee: Alcatel Lucent Shanghai Bell Co Ltd; University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China; Nokia Shanghai Bell Co Ltd
Priority date: 2010-12-20
Filing date: 2010-12-20
Publication date: 2016-01-13
Anticipated expiration: 2030-12-20
Also published as: CN102571660A

Abstract

The object of this invention is to provide a kind of method and apparatus carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency.Wherein, equipment is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission; OFDM process is carried out, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.The present invention introduces the method (RT) adopting reserved frequency in an ofdm system, and for Received signal strength, receiver is easy to abandon the signal for reserved frequency, and the remaining digital signal of making an uproar that adds is sent to detector and normally detected.Therefore, do not need operation bidirectional to carry out restoring signal at receiver end based on the implementation method of the N rank continuous signal of RT, the method brings more freedom to resist the distortion caused by channel and noise in the downlink to receiver simultaneously.

Description

In a communications system based on the continuous OFDM method and apparatus in N rank of RT

Technical field

The present invention relates to the communication technical field based on OFDM, particularly relate to a kind of technology of carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency.

Background technology

OFDM (OFDM) is a very welcome modulation technique possessing many performance advantages, and by IEEE802.11a, IEEE802.11g, IEEE802.16, European digital audio broadcast (DAB), the technical standards such as Digital European broadcast of images (DVB) adopted.But the relatively slow frequency spectrum edge attenuation effect of this technology becomes its subject matter applied in wireless communication system and wired communication system.

Many side lobe suppression methods are suggested and address this problem, but the target of all these methods is all directly reduce out-of-band power; And most methods is all set up the optimal models of a Sidelobe Suppression target function, this makes transmitting terminal become very complicated.Being different from said method, a kind of new method being called N rank continuity method, by keeping N order derivative in the continuity of the time domain boundary point of continuous OFDM symbol, greatly directly can reducing out-of-band power.The enforcement of N rank continuity method is very simple, only needs the inversion operation of compute matrix, even can calculate in advance.A shortcoming of the method introduces distortion, in order to overcome distortion, requires that receiver possesses higher complexity.

Traditional N rank continuity method transmitter terminal implementation as shown in Figure 1, comprise the following steps:

1) i-th OFDM symbol d of length K on frequency domain _i, be sent to mapping block to produce it is i-th OFDM symbol of the reality with very low out-of-band power.Under most simple case, d _ibe made up of phase-shifts keying or integration amplitude modulation symbols.Map mode as shown in equation (1),

{\overset{&OverBar;}{d}}_{i} = (I - P) d_{i} + P F^{H} {\overset{&OverBar;}{d}}_{i - 1}, - - - (1),

Wherein, P=F ^ha ^h(AA ^h) ^-1aF, P are constants determined by exponent number N and the data carrier relative position of N order derivative, and I is with the unit square formation of P matrix with size. it is (i-1) individual OFDM symbol finally delivering to inverse discrete Fourier transform (IDFT) module.() ^hcomplex conjugate transpose, () ^-1it is matrix inversion.Suppose s _it () is the weighted sum of OFDM subcarrier, wherein k ∈ κ={ k ₀, k ₁., k _k-1, T _gfor circulating prefix-length, T _sthe length before not adding Cyclic Prefix in OFDM symbol. and wherein acquired results must be delayed by or preserve in memory for next OFDM symbol mapping process.

2) i-th ofdm signal is on frequency domain the signal in corresponding time domain is obtained by inverse discrete Fourier transform (IDFT) module.

3) head that Cyclic Prefix is placed to time-domain signal comes anti-multipath jamming.

4) digital baseband signal launched finally is produced by Pulse shaped filter.

5) by step 4) in the baseband signal that produces by D/A converter module, be converted to analog signal, then by radiofrequency emitting module, signal moved on suitable frequency band, generate final transmitting.

Find out thus, the continuous OFDM method in traditional N rank introduces distortion to primary signal, needs have extra operation to remove distortion at receiver end.Although this removal distortion operation is not optimum detection signal method, owing to needing at receiver end to carry out iterative processing, receiver end is made to have relatively high complexity.

Therefore, how to provide a kind of and keep N rank continuity OFDM method while avoiding digital signal to introduce distortion, become one of current urgent problem.

Summary of the invention

The object of this invention is to provide a kind of method and apparatus carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency.

According to an aspect of the present invention, provide a kind of method of carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency, wherein, the method comprises the following steps:

A is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission;

B carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.

According to another aspect of the present invention, additionally provide a kind of equipment carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency, wherein, this equipment comprises:

Generating apparatus, for by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, it is for keeping the N rank continuity of signal transmission;

Processing unit, for carrying out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.

Compared with prior art, the present invention introduces the method (RT) adopting reserved frequency in an ofdm system, all available subcarrier is divided into two parts, part subcarrier is used for transfer of data, another part is as reserved frequency, for Sidelobe Suppression, thus keep the N rank continuity of transmission signal.Data-signal d _iwith reserved frequency signal C _ioccupy different frequency domains, such as d _ic _i=0.For Received signal strength, receiver is easy to abandon the signal for reserved frequency, and the remaining digital signal of making an uproar that adds is sent to detector and normally detected.Therefore, do not need operation bidirectional to carry out restoring signal at receiver end based on the implementation method of the N rank continuous signal of RT, the method brings more freedom to resist the distortion caused by channel and noise in the downlink to receiver simultaneously.

Accompanying drawing explanation

By reading the detailed description done non-limiting example done with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:

Fig. 1 is the traditional N rank continuity method high-level schematic functional block diagram in emitter terminals;

Fig. 2 is the method flow diagram carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency according to an aspect of the present invention;

Fig. 3 is the power spectral density plot of traditional N rank continuity method;

Fig. 4 is the power spectral density plot of equidistantly placing the N rank continuity OFDM of reserved frequency based on 32 according to an aspect of the present invention;

Fig. 5 is the power spectral density plot of placing the N rank continuity OFDM of reserved frequency based on 32 at random according to an aspect of the present invention;

Fig. 6 is the power spectral density plot of equidistantly placing the N rank continuity OFDM of reserved frequency based on 64 according to an aspect of the present invention;

Fig. 7 is the power spectral density plot of placing the N rank continuity OFDM of reserved frequency based on 64 at random according to an aspect of the present invention;

Fig. 8 is the high-level schematic functional block diagram in emitter terminals of carrying out the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency according to an aspect of the present invention;

Fig. 9 is the schematic diagram of 3 kinds of reserved frequency modes of emplacements;

Figure 10 is the schematic diagram carrying out the equipment of the continuous OFDM process in N rank in the transmitter of the communication system based on OFDM based on reserved frequency according to another aspect of the present invention.

In accompanying drawing, same or analogous Reference numeral represents same or analogous parts.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

Fig. 2 is the method flow diagram according to one aspect of the invention, and the process of carrying out the continuous OFDM process in N rank in the transmitter based on the communication system of OFDM based on reserved frequency is shown.Wherein, in step sl, transmitter 1 is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission; In step s 2, transmitter 1 carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.At this, described communication system comprises wired communication system or wireless communication system.

Particularly, in step sl, transmitter 1 is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission.More specifically, in step sl, transmitter 1 places data carrier signal and reserved frequency signal by the such as mode such as continuous, equidistant or random, and makes to treat that the data signal sequence of OFDM process generates corresponding preserved signal sequence by the mode mapped.Such as, carrier index set κ is divided into two parts: κ ₁={ k ₀, k ₁..., k _k-nTR-1and κ ₂=k ' _k-nTR, k ' _k-nTR+1..., k ' _k-1, wherein, nTR represents the number of subcarriers of cutting down for reserved and out-of-band power, k ₀< k ₁< ... < k _k-nTR-1, k ' _k-nTR< k ' _k-nTR+1< ... < k ' _k-1; For any p ₁∈ κ ₁, p ₂∈ κ ₂, can not think p ₁< p ₂or p ₁> p ₂; Suppose and

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix}),

Wherein, the F ' of K-nTR row and A ' corresponding digital signals, last nTR row F ' reserved frequency signal corresponding to A '; If B=A ' F ', A ' and the B of first K-nTR row are denoted as respectively as A ₁and B ₁, A ₂with B ₂represent A ' and the B of most rank rear.So preserved signal is for the frequency domain value C of i-th OFDM symbol _iequation specific as follows (2) represents:

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'}, - - - (2),

Accordingly, transmitter 1 is according to treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence.

In step s 2, transmitter 1 carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.Such as, data signal sequence and the preserved signal sequence that generates according to this data signal sequence in step sl combine by transmitter 1, and by inverse discrete Fourier transformer inverse-discrete module (IDFT) by Sequence Transformed for the frequency-region signal after integrating be corresponding time-domain signal; Then adding Cyclic Prefix in the front end of time domain OFDM signal comes anti-multipath jamming, digital baseband signal is produced by Pulse shaped filter, this digital baseband signal is passed through D/A converter module, be converted to analog signal, then by radiofrequency emitting module, signal is moved on suitable frequency band, generate final OFDM symbol waiting for transmission.

Preferably, in step sl, transmitter 1 also generates described preserved signal sequence according to following formula:

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'},

Wherein, C _irepresent the frequency domain value for the preserved signal of i-th OFDM symbol; A ₁and B ₁be respectively following matrix A ' the A ' of first K-nTR row and B, A ₂with B ₂be respectively following matrix A ' A ' of last nTR row and B,

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix})

And B=A ' F ', such as, carrier index set κ is divided into two parts: κ ₁={ k ₀, k ₁., k _k-nTR-1and κ ₂=k ' _k-nTR, k ' _k-nTR+1..., k ' _k-1, wherein, nTR represents the number of subcarriers of cutting down for reserved and out-of-band power, k ₀< k ₁< ... < k _k-nTR-1, k ' _k-nTR< k ' _k-nTR+1< ... < k ' _k-1; For any p ₁∈ κ ₁, p ₂∈ κ ₂, can not think p ₁< p ₂or p ₁> p ₂; Suppose and

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix}),

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'}, - - - (2),

According to equation (2), the value of reserved frequency signal not only depends on data-signal, also depends on the position of data subcarrier and the position of reserved frequency simultaneously.Therefore, for reserved frequency, different preserved signal positions may cause different peak powers and average power.

Following example is based on the ofdm system of 256 subcarriers, and 16QAM modulates.For initial OFDM symbol, C is set ₀=0.By being sampling period Tsamp=Ts/2048=Tg/144, wherein the sampled signal of Ts=1/15ms carrys out estimating power spectrum density (PSD), and after sampling, ofdm signal length is 2048, and circulating prefix-length is 144.Obtain power spectral density (PSD) according to figure average period of 4096 Hamming windows (4096-sampleHanningwindow), sampling overlap length is 512.

For comparison purposes, Fig. 3 illustrates traditional N rank continuity OFDM performance, and wherein, band internal power spectrum is almost flat, and out-of-band power can drop to-80dB simultaneously.

Fig. 4 and Fig. 5 illustrates that 32 the reserved frequencies out-of-band power when equidistant type and casual cnalogy based on the continuous OFDM technology in N rank of RT cuts down performance respectively.The out-of-band power that the present invention can realize about 27db is cut down, and therefore the out-of-band power of N rank continuous print ofdm signal can drop to-72dB.Meanwhile, along with the increase gradually (0-2) of derivative progression, it is more and more faster that transmission bandwidth is decayed.In addition, owing to inserting reserved frequency, the fluctuation of band internal power is about 10db, and does not have the successional signal band internal power fluctuation of N rank to be about 5dB.

As shown in Figure 6 and Figure 7, when reserved frequency is increased to 64 by 32, the reduction of out-of-band power has the gain of extra 3dB, but the fluctuation not too large change of band internal power.

Respectively measurement data subcarrier and reserved average power frequently, to determine that the continuous OFDM technology in N rank based on RT is in the power consumption of reserved frequency and passband fluctuation, table 1 and table 2 illustrate the statistics example based on 20000 OFDM symbol.

Table 1: based on average power consumption (preserved signal quantity=32) example of the continuous OFDM technology in N rank of RT

Table 2: based on average power consumption (preserved signal quantity=32) example of the continuous OFDM technology in N rank of RT

When the placement type of reserved frequency is fixed, and when quantity increases, the power of reserved frequency is linear growth along with the increase of derivative exponent number N.When there being 32 reserved frequencies, the average power of reserved frequency may exceed the power of data-signal.But when adopting more reserved frequency, as 64, the average power of reserved frequency is exactly the half of data-signal average power at the most.In addition, derivative exponent number N is usually much little than data subcarrier K.Therefore, when number of subcarriers is very large, the power consumption of reserved frequency is negligible.

For the type of placing continuously, reserved frequency signal is too concentrated, cause the power being greater than data-signal the peak power average in reserved frequency, but the performance that its out-of-band power is cut down almost with is equidistantly placed, is placed identical at random, does not repeat them here.

Preferably, in step s 2, transmitter 1 also carries out subcarrier mapping to described data signal sequence and described preserved signal sequence; OFDM process is carried out, to generate OFDM symbol waiting for transmission to the described data signal sequence mapped through subcarrier and described preserved signal sequence.As shown in Figure 8, realize according to the following steps in the continuous OFDM technology in N rank of transmitter terminal based on RT:

1) in i-th OFDM symbol, by the frequency-region signal d ' of K-nTR length _idelivering to mapping block according to equation (2) computational length is the C ' of nTR _ivalue;

2) by sub-carrier mapping module, signal d ' _iwith C ' _ibe integrated together and be mapped on their each self-corresponding subcarriers and produce complete OFDM symbol

3) the frequency-region signal d of i-th OFDM symbol _icorresponding time-domain signal is converted into by inverse discrete Fourier transformer inverse-discrete module (IDFT);

4) adding Cyclic Prefix in the front end of time domain OFDM signal comes anti-multipath jamming;

5) the final digital baseband signal launched is produced by pulse shaping filter module;

6) by step 5) in produce digital baseband signal turn modular converter by digital-to-analogue, be converted to analog signal, then by radiofrequency emitting module, signal moved on suitable frequency band, generate final OFDM symbol waiting for transmission.

More preferably, described subcarrier maps and includes but not limited to, any one mode below:

1) by extremely continuous for the described preserved signal sequence mapping subcarrier placed;

2) by described preserved signal sequence mapping to the subcarrier be equally spaced;

3) by described preserved signal sequence mapping to the subcarrier of random distribution.

Wherein, for continuous print type, all reserved frequencies must put together; For equidistant type, reserved frequency is distributed in all carrier waves equally spacedly; For casual cnalogy, reserved frequency is random distribution, and remaining frequency is for transmitting data carrier.As shown in Figure 9, the sub-block of oblique line represents that the position of transfer of data subcarrier, the sub-block of grid line represent the position of reserved frequency.

Figure 10 is equipment schematic diagram according to a further aspect of the present invention, and the equipment carrying out the continuous OFDM process in N rank in the transmitter based on the communication system of OFDM based on reserved frequency is shown.Wherein, equipment 1 comprises generating apparatus 11 and processing unit 12.Particularly, generating apparatus 11 is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission; Processing unit 12 carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.At this, described communication system comprises wired communication system or wireless communication system.

Particularly, generating apparatus 11 is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, and it is for keeping the N rank continuity of signal transmission.More specifically, generating apparatus 11 places data carrier signal and reserved frequency signal by the such as mode such as continuous, equidistant or random, and makes to treat that the data signal sequence of OFDM process generates corresponding preserved signal sequence by the mode mapped.Such as, carrier index set κ is divided into two parts: κ ₁={ k ₀, k ₁..., k _k-nTR-1and κ ₂=k ' _k-nTR, k ' _k-nTR+1..., k ' _k-1, wherein, nTR represents the number of subcarriers of cutting down for reserved and out-of-band power, k ₀< k ₁< ... < k _k-nTR-1, k ' _k-nTR< k ' _k-nTR+1< ... < k ' _k-1; For any p ₁∈ κ ₁, p ₂∈ κ ₂, can not think p ₁< p ₂or p ₁> p ₂; Suppose and

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix}),

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'}, - - - (2),

Accordingly, generating apparatus 11 is according to treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence.

Processing unit 12 carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence.Such as, the preserved signal sequence that data signal sequence and generating apparatus 11 generate according to this data signal sequence combines by processing unit 12, and by inverse discrete Fourier transformer inverse-discrete module (IDFT) by integrate after frequency-region signal Sequence Transformed be corresponding time-domain signal; Then adding Cyclic Prefix in the front end of time domain OFDM signal comes anti-multipath jamming, digital baseband signal is produced by Pulse shaped filter, this digital baseband signal is passed through D/A converter module, be converted to analog signal, then by radiofrequency emitting module, signal is moved on suitable frequency band, generate final OFDM symbol waiting for transmission.

Preferably, generating apparatus 11 also generates described preserved signal sequence according to following formula:

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'},

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix})

And B=A ' F ', such as, carrier index set κ is divided into two parts: κ ₁={ k ₀, k ₁..., k _k-nTR-1and κ ₂=k ' _k-nTR, k ' _k-nTR+1..., k ' _k-1, wherein, nTR represents the number of subcarriers of cutting down for reserved and out-of-band power, k ₀< k ₁< ... < k _k-nTR-1, k ' _k-nTR< k ' _k-nTR+1< ... < k ' _k-1; For any p ₁∈ κ ₁, p ₂∈ κ ₂, can not think p ₁< p ₂or p ₁> p ₂;

Suppose and

A^{'} = (\begin{matrix} 1 & 1 & \cdot \cdot \cdot & 1 & 1 & 1 & \cdot \cdot \cdot & 1 \\ k_{0} & k_{1} & \cdot \cdot \cdot & k_{K - nTR - 1} & k_{K - nTR}^{'} & k_{K - nTR + 1}^{'} & \cdot \cdot \cdot & k_{K - 1}^{'} \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ \cdot & \cdot & \cdot & \cdot & \cdot & \cdot \\ k_{0}^{N} & k_{1}^{N} & \cdot \cdot \cdot & k_{K - nTR - 1}^{N} & k_{K - nTR}^{' N} & k_{K - nTR + 1}^{' N} & \cdot \cdot \cdot & k_{K - 1}^{' N} \end{matrix}),

C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'})

= B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'}, - - - (2),

For comparison purposes, Fig. 4 illustrates traditional N rank continuity OFDM performance, and wherein, band internal power spectrum is almost flat, and out-of-band power can drop to-80dB simultaneously.

Fig. 5 and Fig. 6 illustrates that 32 the reserved frequencies out-of-band power when equidistant type and casual cnalogy based on the continuous OFDM technology in N rank of RT cuts down performance respectively.The out-of-band power that the present invention can realize about 27db is cut down, and therefore the out-of-band power of N rank continuous print ofdm signal can drop to-72dB.Meanwhile, along with the increase gradually (0-2) of derivative progression, it is more and more faster that transmission bandwidth is decayed.In addition, owing to inserting reserved frequency, the fluctuation of band internal power is about 10db, and does not have the successional signal band internal power fluctuation of N rank to be about 5dB.

As shown in Figure 7 and Figure 8, when reserved frequency is increased to 64 by 32, the reduction of out-of-band power has the gain of extra 3dB, but the fluctuation not too large change of band internal power.

Respectively measurement data subcarrier and reserved average power frequently, to determine that the continuous OFDM technology in N rank based on RT is in the power consumption of reserved frequency and passband fluctuation, table 3 and table 4 illustrate the statistics example based on 20000 OFDM symbol.

Table 3: based on average power consumption (preserved signal quantity=32) example of the continuous OFDM technology in N rank of RT

Table 4: based on average power consumption (preserved signal quantity=32) example of the continuous OFDM technology in N rank of RT

Preferably, processing unit 12 also comprises subcarrier mapping device 121 and OFDM processing unit 122, and wherein, subcarrier mapping device 121 carries out subcarrier mapping to described data signal sequence and described preserved signal sequence; OFDM processing unit 122 carries out OFDM process, to generate OFDM symbol waiting for transmission to the described data signal sequence mapped through subcarrier and described preserved signal sequence.As shown in Figure 8, realize according to the following steps in the continuous OFDM technology in N rank of transmitter terminal based on RT:

2) by sub-carrier mapping module, signal d ' _iwith C ' _ibe integrated together and be mapped on their each self-corresponding subcarriers and produce complete OFDM symbol ;

To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned one exemplary embodiment, and when not deviating from spirit of the present invention or essential characteristic, the present invention can be realized in other specific forms.Therefore, no matter from which point, all should embodiment be regarded as exemplary, and be nonrestrictive, scope of the present invention is limited by claims instead of above-mentioned explanation, and all changes be therefore intended in the implication of the equivalency by dropping on claim and scope are included in the present invention.Any Reference numeral in claim should be considered as the claim involved by limiting.In addition, obviously " comprising " one word do not get rid of other unit or step, odd number does not get rid of plural number.Multiple unit of stating in system claims or device also can be realized by software or hardware by a unit or device.First, second word such as grade is used for representing title, and does not represent any specific order.

Claims

1. in the transmitter of the communication system based on OFDM, carry out a method for the continuous OFDM process in N rank based on reserved frequency, wherein, the method comprises the following steps:

A is by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, it is for keeping the N rank continuity of signal transmission, and wherein, available subcarrier is divided into two parts, a part is used to described data signal sequence, and another part is used to described preserved signal sequence;

B carries out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence;

Wherein, described OFDM process comprises:

-described data signal sequence and described preserved signal sequence are mapped on each self-corresponding subcarrier and produce complete ofdm signal;

-described ofdm signal is converted into corresponding time-domain signal by inverse discrete Fourier transformer inverse-discrete module;

-adding Cyclic Prefix in the front end of time domain OFDM signal comes anti-multipath jamming, produces digital baseband signal via pulse shaping filter module, and the analog signal being converted to correspondence further moves on suitable frequency band, to generate OFDM symbol waiting for transmission.

2. method according to claim 1, wherein, described step a also comprises: generate described preserved signal sequence according to following formula:

\begin{matrix} C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'}) \\ = B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'} \end{matrix},

Wherein, C ' _irepresent and correspond to i-th OFDM symbol d ' in described data signal sequence _ithe frequency domain value of preserved signal;

The quantity of available subcarrier is K, and it comprises subset κ ₁={ k ₀, k ₁..., k _k-nTR-1and κ ₂=k ' _k-nTR, k ' _k-nTR+1..., k ' _k-1, subset K ₁be used to transmit described data signal sequence, subset K ₂be used to transmit described preserved signal sequence;

A ₁and B ₁be respectively following matrix A ' the A ' of front K-nTR row and B, A ₂with B ₂be respectively A ' and the B of following matrix A ' rear nTR row,

A^{'} = (\begin{matrix} 1 & 1 & ... & 1 & 1 & 1 & ... & 1 \\ k_{0} & k_{1} & ... & k_{K - n T R - 1} & k_{K - n T R}^{'} & k_{K - n T R + 1}^{'} & ... & k_{K - 1}^{'} \\ \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} \\ k_{0}^{N} & k_{1}^{N} & ... & k_{K - n T R - 1}^{N} & k_{K - n T R}^{' N} & k_{K - n T R + 1}^{' N} & ... & k_{K - 1}^{' N} \end{matrix})

And B=A ' F ',

F^{'} = d i a g (e^{{jφk}_{0}}, e^{{jφk}_{1}}, ..., e^{{jφk}_{K - n T R - 1}}, e^{{jφk}_{K - n T R - 1}^{'}}, e^{{jφk}_{K - n T R + 1}^{'}}, ..., e^{{jφk}_{K - 1}^{'}})

t _gfor circulating prefix-length, T _sfor described time domain OFDM signal does not add the length before Cyclic Prefix.

3. method according to claim 1, wherein, the mode that described preserved signal sequence carries out subcarrier mapping comprises following any one:

-by extremely continuous for the described preserved signal sequence mapping subcarrier placed;

-by described preserved signal sequence mapping to the subcarrier be equally spaced;

-by described preserved signal sequence mapping to the subcarrier of random distribution.

4. according to the method in any one of claims 1 to 3, wherein, described communication system comprises wired communication system or wireless communication system.

5. carry out an equipment for the continuous OFDM process in N rank in based on the transmitter of ofdm communication system based on reserved frequency, wherein, this equipment comprises:

Generating apparatus, for by treating that the data signal sequence of OFDM process generates corresponding preserved signal sequence, it is for keeping the N rank continuity of signal transmission, wherein, available subcarrier is divided into two parts, a part is used to described data signal sequence, and another part is used to described preserved signal sequence;

Processing unit, for carrying out OFDM process, to generate OFDM symbol waiting for transmission to described data signal sequence and described preserved signal sequence;

Wherein, described OFDM process comprises:

6. equipment according to claim 5, wherein, described generating apparatus is also for generating described preserved signal sequence according to following formula:

\begin{matrix} C_{i}^{'} = B_{2}^{+} (A_{1} d_{i - 1}^{'} + A_{2} C_{i - 1}^{'} - B_{1} d_{i}^{'}) \\ = B_{2}^{+} A_{2} C_{i - 1}^{'} + B_{2}^{+} A_{1} d_{i - 1}^{'} - B_{2}^{+} B_{1} d_{i}^{'} \end{matrix},

Wherein, C ' _irepresent and correspond to i-th OFDM symbol in described data signal sequence d ' _ithe frequency domain value of preserved signal;

A^{'} = (\begin{matrix} 1 & 1 & ... & 1 & 1 & 1 & ... & 1 \\ k_{0} & k_{1} & ... & k_{K - n T R - 1} & k_{K - n T R}^{'} & k_{K - n T R + 1}^{'} & ... & k_{K - 1}^{'} \\ \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} & \begin{matrix} . \\ . \\ . \end{matrix} \\ k_{0}^{N} & k_{1}^{N} & ... & k_{K - n T R - 1}^{N} & k_{K - n T R}^{' N} & k_{K - n T R + 1}^{' N} & ... & k_{K - 1}^{' N} \end{matrix})

And B=A ' F ',

F^{'} = d i a g (e^{{jφk}_{0}}, e^{{jφk}_{1}}, ..., e^{{jφk}_{K - n T R - 1}}, e^{{jφk}_{K - n T R - 1}^{'}}, e^{{jφk}_{K - n T R + 1}^{'}}, ..., e^{{jφk}_{K - 1}^{'}})

7. equipment according to claim 5, wherein, the mode that described preserved signal sequence carries out subcarrier mapping comprises following any one:

8. the equipment according to any one of claim 5 to 7, wherein, described communication system comprises wired communication system or wireless communication system.