CN102098259B - Signal emission method in multi-subband orthogonal frequency division multiplexing (OFDM) system - Google Patents

Abstract

The invention provides a signal emission method in a multi-subband orthogonal frequency division multiplexing (OFDM) system, comprising the following steps: subsection is carried out on the signals to be transmitted when an effective subcarrier on a subband can not bear the data volume of signals to be transmitted in a unit time; and effective subcarriers on a same subband are utilized to transmit each section of signals to be transmitted in different unit times. The method is utilized to ensure performances related to time domains of signals which are transmitted by a system.

Description

Signal transmitting method in many subbands ofdm system

Technical field

The present invention relates to many subbands ofdm system technical field, relate in particular to the signal transmitting method in a kind of many subbands ofdm system.

Background technology

In mobile communication system, when subscriber equipment (UE) changes base station coverage area in start or from signal blind zone, need to carry out Cell searching.By cell search process, time and Frequency Synchronization are obtained in UE and residential quarter, and detect cell index (ID), in order to be linked into respective cell according to this residential quarter ID.

In OFDM (OFDM) system, master sync signal (PSC) and auxiliary synchronous signals (SSC) characterized residential quarter id information are adopted in the base station, UE receives master sync signal and auxiliary synchronous signals by descending synchronous signal channel, carries out Cell searching according to the master sync signal and the auxiliary synchronous signals that receive.

Fig. 1 is the time-frequency resource allocating schematic diagram that the base station sends master sync signal and auxiliary synchronous signals in the prior art.

Among Fig. 1, mobile communication system takies one section continuous system bandwidth.As shown in Figure 1, a radio frames comprises 10 subframes, and each subframe is comprised of a plurality of OFDM symbol times.The base station takies two OFDM symbol times and is respectively applied to send master sync signal and auxiliary synchronous signals.In addition, because system bandwidth is continuous, so the base station has selected the part of continuous system bandwidth to be used for sending master sync signal and auxiliary synchronous signals.As exemplarily, in Fig. 1, the 7th the OFDM symbol time that the base station has taken on thesubframe 0 sends auxiliary synchronous signals, the 3rd the OFDM symbol time that has taken on thesubframe 1 sends master sync signal, and it is that the frequency resource of 1.08MHz is used for transmission master sync signal and auxiliary synchronous signals that the base station takies width in the continuous system bandwidth.

UE detects master sync signal and auxiliary synchronous signals by the signal that receives is carried out the time domain coherent detection, carries out Cell searching according to detected master sync signal and auxiliary synchronous signals.

In many subbands ofdm system, system bandwidth is comprised of a plurality of continuous or discrete subbands.For example, the electric power load monitoring and control communication network is exactly a kind of typical many subbands ofdm system.

Fig. 2 is the frequency resource distribution schematic diagram that the electric power load monitoring and control communication network takies.

As shown in Figure 2, the frequency resource of electric power load monitoring and control communication network is distributed on the frequency range of 230MHz discretely, and its bandwidth is 8.15MHz, and the subband by 40 25kHz forms altogether, the subband of minimum frequency is positioned at the 223.525MHz place, and the subband of high frequency points is positioned at the 231.65MHz place.

In many subbands ofdm system, the base station adopts orthogonal frequency division multiplexi to transmit at each subband.Because the frequency resource of each subband is limited, effective subcarrier number of carrying also is restricted.Wherein, all subcarriers of a subband comprise effective subcarrier and virtual subnet carrier wave, and usually effectively subcarrier takies the mid portion of the frequency resource that described subband takies, the marginal portion of the frequency resource that the described subband of virtual subnet carrier occupancy takies.Effective subcarrier wherein can carry and transmit, and the virtual subnet carrier wave does not carry in the actual signal emission process and transmits.

When the data volume of certain type signal exceeded the bearing capacity of all effective subcarriers on the subband, the method that adopts at present was that the base station adopts a plurality of subbands to send the signal of the type.

For example, when many subbands orthogonal frequency division multiplexi is adopted in the base station, if be used for the bearing capacity that the data volume of the master sync signal of Cell searching and auxiliary synchronous signals has exceeded all effective subcarriers on the subband, according to present method, the base station will send master sync signal and auxiliary synchronous signals at a plurality of subbands.Yet, because the difference that exists between the channel condition of each subband adopts a plurality of subbands transmission master sync signals and auxiliary synchronous signals will cause the relativity of time domain energy of master sync signal and the relativity of time domain of auxiliary synchronous signals to be affected.Because need to carrying out to the signal that receives the relativity of time domain detection, UE just can obtain master sync signal and auxiliary synchronous signals, and then carry out Cell searching according to master sync signal and auxiliary synchronous signals, therefore, when the base station when a plurality of subbands send master sync signals and auxiliary synchronous signals, the precision that will cause UE to detect master sync signal and auxiliary synchronous signals reduces, and then affects the Cell searching result of UE.

Summary of the invention

In view of this, the invention provides the signal transmitting method in a kind of many subbands ofdm system, with the relativity of time domain energy of the signal of assurance system emission.

Signal transmitting method in a kind of many subbands ofdm system, the method comprises:

When within a unit interval, utilizing effective subcarrier on the subband can't carry the data volume of signal to be transmitted, with the signal to be transmitted segmentation, utilize respectively the subcarrier on the same subband to launch each section signal to be transmitted within the different unit interval, the described different unit interval is continuous each other;

Wherein, transmitting terminal is at first with the signal to be transmitted segmentation of frequency domain form, and the sequencing of shared unit interval of each section signal to be transmitted and each section signal to be transmitted putting in order before carrying out described staged operation is identical, and the signal to be transmitted of each section frequency domain form is converted to respectively again emission behind the time-domain signal;

Wherein, transmitting terminal is converted to respectively time-domain signal with the signal to be transmitted of each section frequency domain form, sequencing according to the shared unit interval of each section signal to be transmitted, connect successively corresponding time-domain signal, the signal of the afterbody predetermined length of the time-domain signal after connecting is added to the head of the time-domain signal after this connection as Cyclic Prefix (CP), be transmitted in the described time-domain signal that head has added CP.

As seen from the above technical solution, the present invention passes through the signal to be transmitted segmentation, within the different unit interval, utilize the subcarrier on the same subband to launch each section signal to be transmitted, be that the present invention is by expanding in time domain, within a plurality of different unit interval, launch signal to be transmitted, solved signal to be transmitted because the problem on the excessive subband that can't be carried in the unit interval of data volume.And, because the present invention is carried on the signal to be transmitted of launching in the different unit interval in the subband, solved the problem that is carried on the relativity of time domain energy that affects signal to be transmitted in the discontinuous different sub-band owing to signal to be transmitted.

Description of drawings

Fig. 1 is the time-frequency resource allocating schematic diagram that the base station sends master sync signal and auxiliary synchronous signals in the prior art.

Fig. 2 is the frequency resource distribution schematic diagram that the electric power load monitoring and control communication network takies.

Fig. 3 is the signal transmitting method flow chart in many subbands ofdm system provided by the invention.

Fig. 4 is the method flow diagram of emission master sync signal provided by the invention and auxiliary synchronous signals.

Fig. 5 is the schematic diagram that synchronizing channel takies the running time-frequency resource position in the one embodiment of the invention in radio frames.

Fig. 6 is that emission length is the method flow diagram of 62 master sync signal.

Fig. 7 is that length is the frequency resource schematic diagram that 6 signal to be transmitted subsegment takies.

Fig. 8 is that length is the frequency resource schematic diagram that 10 signal to be transmitted subsegment takies.

Fig. 9 is the small region search method flow chart.

Embodiment

Fig. 3 is the signal transmitting method flow chart in many subbands ofdm system provided by the invention.

As shown in Figure 3, the method comprises:

Step 301 is when utilizing effective subcarrier on the subband can't carry the data volume of signal to be transmitted within a unit interval, with the signal to be transmitted segmentation.

In this step, if within a unit interval, can utilize the effective subcarrier emission signal to be transmitted on the subband, then can be not with this signal to be transmitted segmentation, but directly this signal to be transmitted is utilized effective subcarrier emission on the subband within a unit interval.

Wherein, the described unit interval typically refers to an OFDM symbol time.

Step 302 utilizes respectively the effective subcarrier on the same subband to launch each section signal to be transmitted within the different unit interval.

If within a unit interval, because the data volume of signal to be transmitted is excessive, cause the effective subcarrier on the subband can't carry signal to be transmitted, then need the signal to be transmitted segmentation, then within the different unit interval, utilize respectively the effective subcarrier on the same sub-band to launch each section signal to be transmitted, the described different unit interval is continuous each other.

The length of every segment signal of telling in this step is no more than the number of all effective subcarriers that the shared subband of signal to be transmitted carries within a unit interval, to guarantee the signal to be transmitted after described subband can carry segmentation.

In brief, the time-domain resource that the present invention transmits and takies by expansion, and keep transmitting taking identical frequency domain resource in different time-domain resource, can either succeed in sending up signal, can guarantee again the relativity of time domain energy of signal.

In the described method of Fig. 3, transmitting terminal is at first with the signal to be transmitted segmentation of frequency domain form, and the sequencing of shared unit interval of each section signal to be transmitted and each section signal to be transmitted putting in order before carrying out described staged operation is identical, and the signal to be transmitted of each section frequency domain form is converted to respectively again emission behind the time-domain signal.

Particularly, transmitting terminal is converted to respectively time-domain signal with the signal to be transmitted of each section frequency domain form, sequencing according to the shared unit interval of each section signal to be transmitted, connect successively corresponding time-domain signal, the signal of the afterbody predetermined length of the time-domain signal after connecting is added to the head of the time-domain signal after this connection as Cyclic Prefix (CP), be transmitted in the described time-domain signal that head has added CP.

The typical application scenarios of the described method of Fig. 3 is that the base station is to subscriber equipment emission master sync signal and auxiliary synchronous signals.

Fig. 4 is the method flow diagram of emission master sync signal provided by the invention and auxiliary synchronous signals.

As shown in Figure 4, the method comprises:

Step 401, transmitting terminal is divided into several subsegments successively with the synchronizing signal of the frequency domain form of generation, and the length of each subsegment is no more than effective number of sub carrier wave that an OFDM symbol time carries.

In this step, described synchronizing signal comprises master sync signal and auxiliary synchronous signals.On frequency domain, master sync signal and auxiliary synchronous signals take a subband jointly; On time domain, each radio frames can be placed a primary synchronization channel and an auxiliary synchronization channel at least, and primary synchronization channel and auxiliary synchronization channel can be adjacent on time domain, also can the certain sampled distance in interval.In a radio frames, can place first master sync signal, rear placement auxiliary synchronous signals also can be placed first auxiliary synchronous signals, places master sync signal again.

Wherein, jointly to take a subband be for the ease of utilizing master sync signal to the auxiliary synchronous signals detection that is concerned with, improving relevant detection accuracy for master sync signal and auxiliary synchronous signals.

Step 402, transmitting terminal on the time domain is being mapped to the different subsegments of synchronizing signal on the different OFDM symbol times in order, and each subsegment takies subband identical on the frequency domain resource.

Step 403, transmitting terminal is done respectively the IFFT conversion to transmitting of the frequency domain form on each OFDM symbol time, converts forms of time and space transmitting to from frequency domain form.

Step 404, transmitting terminal adds the data that are converted to the afterbody predetermined length that transmits of forms of time and space to transmit head, namely utilizes the tail data that transmits to be the interpolation Cyclic Prefix that transmits.

By the time domain circular dependency that is the interpolation Cyclic Prefix that transmits, can improves to transmit, thereby improve the accuracy that the time domain circular dependency of utilizing signal is carried out Cell searching.

Transmitting terminal among Fig. 4 is the base station normally.

Fig. 5 is the schematic diagram that synchronizing channel takies the running time-frequency resource position in the one embodiment of the invention in radio frames.

On frequency domain, primary synchronization channel and auxiliary synchronization channel take a subband jointly.On time domain, each radio frames is placed a primary synchronization channel and an auxiliary synchronization channel.Auxiliary synchronization channel takies front 463 sampled points of a radio frames, and primary synchronization channel takies 462 sampled points after the auxiliary synchronization channel.

The below carries out exemplary illustration as example to the described method of Fig. 4 take the length of the master sync signal of armed frequency domain form as 62, specifically sees also Fig. 6.

Fig. 6 is that emission length is the method flow diagram of 62 master sync signal.

As shown in Figure 6, the method comprises:

Step 601, transmitting terminal are that 62 master sync signal is divided into 7 subsegments successively with length, and the length that the length of first subsegment and last subsegment is 6 points, all the other subsegments is 10 points.

Step 602 is mapped to 7 subsegment sequences respectively on the sampled point of corresponding OFDM symbol time.

Wherein, each OFDM symbol time comprises 64 sampled points (namely to 64 subcarriers should be arranged), length is that 6 subsegment is mapped on the 28-33 work song carrier wave according to the mode of Fig. 7, and length is that 10 subsegment is mapped on the 28-37 work song carrier wave according to the mode of Fig. 8.

Wherein, Fig. 7 is that length is the frequency resource schematic diagram that 6 signal to be transmitted subsegment takies.

Fig. 8 is that length is the frequency resource schematic diagram that 10 signal to be transmitted subsegment takies.

Step 603 is respectively 64 IFFT with the frequency domain data on 7 OFDM symbols and is transformed into time domain data, and the time domain data after the conversion is carried out serial arrangement according to the sequencing of the OFDM symbol time that takies, and generates the time domain data of 448 sampled points.

Step 604, transmitting terminal are that the time domain data of described 448 sampled points adds Cyclic Prefix.

In this step, the data of the afterbody predetermined length of the time domain data of described 448 sampled points are added to the head of the time domain data of described 448 sampled points as Cyclic Prefix.In this example, because the restriction of wireless frame structure, the circulating prefix-length that adds for master sync signal is 14 sampled points, CP the length of adding for auxiliary synchronous signals is 15 sampled points, correspondingly, the sampled point of master sync signal is 462 points, and the sampled point of auxiliary synchronous signals is 463 points.

Wherein, master sync signal can be generated by the Zadoff-Chu sequence, generates formula as follows,

$d_u\left(n\right)=\left\{\begin{array}{cc}{e}^{-j\frac{\mathrm{\πun}(n+1)}{63}}& n=\mathrm{0,1},...,30\\ e^{-j\frac{\mathrm{\πu}(n+1)(n+2)}{63}}& n=\mathrm{31,32},...,61\end{array}\right.---\left(1\right)$

Table 1 definition provides the relation of sector ID and Zadoff-Chu sequence u parameter:

Table 1

Auxiliary synchronous signals can be generated by 62 m sequences.Auxiliary synchronous signals is that 62 binary sequence consists of by length, sequence be designated as d (0) ..., d (2n), d (2n+1) ..., d (61).This sequence is that the staggered serial connection of 31 binary sequence consists of by two length.Concrete constructive method is as follows:

$d\left(2n\right)=s_0^{\left(m_0\right)}\left(n\right)c_0\left(n\right)$

$d(2n+1)=s_1^{\left(m_1\right)}\left(n\right)c_1\left(n\right)z_1^{\left(m_0\right)}\left(n\right)---\left(2\right)$

Wherein, 0≤n≤30.Indexing parameter m₀And m₁According to cell group identificationDetermine:

m₀=m′mod31

SequenceWithAccording toparameter m 0 and m1 value to the m sequence

Carry out obtaining after the cyclic shift, wherein:

$s_0^{\left(m_0\right)}\left(n\right)=\tilde{s}\left((n+m_0)\mathrm{mod}31\right)$

$s_1^{\left(m_1\right)}\left(n\right)=\tilde{s}\left((n+m_1)\mathrm{mod}31\right)---\left(4\right)$

Wherein

0≤i≤30, x (i) is defined as

x(i+5)=(x(i+2)+x(i))mod2,0≤i≤25 （5）

Initial condition is: x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

Scrambler sequence c₀(n) and c₁(n) can be according to sector ID and to the m sequence

The cyclic shift structure obtains:

$c_0\left(n\right)=\tilde{c}\left((n+N_{\mathrm{ID}}^{\left(2\right)})\mathrm{mod}31\right)$

$c_1\left(n\right)=\tilde{c}\left((n+N_{\mathrm{ID}}^{\left(2\right)}+3)\mathrm{mod}31\right)---\left(6\right)$

WhereinRepresent sector ID, and

0≤i≤30, x (i) is defined as:

x(i+5)＝(x(i+3)+x(i))mod2,0≤i≤25 （7）

Initial condition is x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

Scrambler sequence

With

Can be according toparameter m 0 and m1 value to the m sequence

Cyclic shift obtains:

$z_1^{\left(m_0\right)}\left(n\right)=\tilde{z}\left((n+\left({\mathrm{<figure-callout\; label="m"\; filenames="HSA00000218334700022.png"\; state="\{\{state\}\}">m</figure-callout>}}_0\mathrm{mod}8\right))\mathrm{mod}31\right)$

$z_1^{\left(m_1\right)}\left(n\right)=\tilde{z}\left((n+\left({\mathrm{<figure-callout\; label="m"\; filenames="HSA00000218334700022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1\mathrm{mod}8\right))\mathrm{mod}31\right)---\left(8\right)$

Wherein

0≤i≤30, x (i) is defined as:

x(i+5)=(x(i+4)+x(i+2)+x(i+1)+x(i))mod2,0≤i≤25 （9）

Initial condition is: x (0)=0, x (1)=0, x (2)=0, x (3)=0, x (4)=1.

After subscriber equipment receives master sync signal and auxiliary synchronous signals, can carry out Cell searching according to master sync signal and auxiliary synchronous signals, specifically see also Fig. 9.

Fig. 9 is the small region search method flow chart.

As shown in Figure 9, the method comprises:

Step 901, the subscriber equipment receiving baseband signal.

Wherein, in the time domain sequences of the alternative master sync signal of the local storage of subscriber equipment, wherein, the production method of alternative master sync signal is identical with the production method of described master sync signal in advance.

Step 902, subscriber equipment carries out the Symbol Timing estimation according to the baseband signal that receives and sector ID detects.

Wherein, it is relevant that the alternative master sync signal of subscriber equipment utilization this locality and the base band time domain signal that receives are slided, and carries out according to the slip correlated results that Symbol Timing is estimated and the sector ID detection.Particularly, choosing sector ID value corresponding to alternative master sync signal with maximum related value is testing result, and the position of recording this maximum related value utilizes timing estimation results to adjust symbol sampler regularly, and then finishes timing synchronization procedure as timing estimation results.

Wherein, Symbol Timing estimation and sector ID detect and can adopt existing method to realize.

Step 903, subscriber equipment carries out Nonlinear Transformation in Frequency Offset Estimation.

Step 904, subscriber equipment carries out compensate of frequency deviation according to frequency offset estimation result.

Wherein, frequency deviation estimation and compensate of frequency deviation can adopt existing techniques in realizing.

Step 905, subscriber equipment are carried out cell set ID search, process ends.

In this step, subscriber equipment obtains the master sync signal original position according to the Symbol Timing estimated result, from this original position, and the time-domain signal of intercepting master sync signal, segmentation is done the FFT conversion and is obtained frequency-region signal to time-domain signal, utilizes this frequency-region signal to calculate domain channel response.Simultaneously extrapolate the auxiliary synchronous signals original position according to the master sync signal original position, the time-domain signal of intercepting auxiliary synchronous signals, segmentation is done the FFT conversion and is obtained auxiliary synchronous frequency-region signal to time-domain signal.Subscriber equipment is done relevant the detection according to the domain channel response of master sync signal to auxiliary synchronous frequency-region signal, obtains the frequency domain estimated value of auxiliary synchronous signals.

The correlation peak of the synchronizing signal of calculating subscriber equipment this locality and the frequency domain estimated value of auxiliary synchronous signals is according to the location positioning cell set ID of the strongest relevant peaks.

The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of making, is equal to replacement, improvement etc., all should be included within the scope of protection of the invention.

Claims (4)

Translated fromChinese

1.一种多子带正交频分复用系统中的信号发射方法，其特征在于，该方法包括：1. A method for transmitting signals in a multi-subband OFDM system, characterized in that the method comprises:当在一个单位时间内利用一个子带上的有效子载波无法承载待发射信号的数据量时，将待发射信号分段，分别在不同的单位时间内利用同一个子带上的有效子载波发射各段待发射信号，所述不同的单位时间彼此连续；When the effective subcarriers on one subband cannot carry the data volume of the signal to be transmitted within a unit time, the signal to be transmitted is segmented, and the effective subcarriers on the same subband are used to transmit each subcarrier in different unit times. a segment of the signal to be transmitted, the different unit times are consecutive to each other;其中，发射端首先将频域形式的待发射信号分段，并且各段待发射信号所占用单位时间的先后顺序与各段待发射信号在执行所述分段操作前的排列顺序相同，将各段频域形式的待发射信号分别转换为时域信号后再发射；Wherein, the transmitter first divides the signal to be transmitted in the frequency domain into segments, and the order of the unit time occupied by each segment of the signal to be transmitted is the same as the sequence of each segment of the signal to be transmitted before performing the segmentation operation. The signals to be transmitted in the form of frequency domains are respectively converted into time domain signals and then transmitted;其中，发射端将各段频域形式的待发射信号分别转换为时域信号，按照各段待发射信号所占用单位时间的先后顺序，依次连接相应的时域信号，将连接后的时域信号的尾部预定长度的信号作为循环前缀（CP）添加到该连接后的时域信号的头部，发射在头部添加了CP的所述时域信号。Among them, the transmitting end converts the signals to be transmitted in the frequency domain form of each segment into time domain signals, and connects the corresponding time domain signals sequentially according to the order of the unit time occupied by each segment of the signals to be transmitted, and the connected time domain signals A signal with a predetermined length at the end of the signal is added as a cyclic prefix (CP) to the head of the connected time-domain signal, and the time-domain signal with the CP added to the head is transmitted.2.根据权利要求1所述的信号发射方法，其特征在于，所述将待发射信号2. The signal transmission method according to claim 1, wherein the signal to be transmitted分段包括：Segments include:分出的每段信号的长度不超过待发射信号所占用的子带在一个单位时间内承载的所有有效子载波的个数。The length of each divided signal segment does not exceed the number of all effective subcarriers carried by the subband occupied by the signal to be transmitted in a unit time.3.根据权利要求1所述的信号发射方法，其特征在于，3. The signal transmission method according to claim 1, characterized in that,所述一个单位时间是一个OFDM符号时间。The one unit time is one OFDM symbol time.4.根据权利要求1所述的信号发射方法，其特征在于，4. The signal transmitting method according to claim 1, characterized in that,所述待发射信号包括主同步信号和辅同步信号。The signal to be transmitted includes a primary synchronization signal and a secondary synchronization signal.

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