CN102098259A - 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, subscriber equipment (UE) need carry out Cell searching in start or when signal blind zone changes base station coverage area over to.By cell search process, time and Frequency Synchronization are obtained in UE and sub-district, and detect cell index (ID), so that be linked into respective cell according to this sub-district ID.

In OFDM (OFDM) system, the base station adopts master sync signal (PSC) and auxiliary synchronous signals (SSC) to characterize the sub-district id information jointly, 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 made up of a plurality of OFDM symbol times.The base station takies two OFDM symbol times and is respectively applied for transmission master sync signal and auxiliary synchronous signals.In addition, because system bandwidth is continuous, so the base station has selected for use the part of continuous system bandwidth to be used to send 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 the subframe 0 sends auxiliary synchronous signals, the 3rd the OFDM symbol time that has taken on the subframe 1 sends master sync signal, and it is that the frequency resource of 1.08MHz is used to transmit 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 made up 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, is made up of the subband of 40 25kHz 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 on 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 was at present, and 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 on 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 carrying out the relativity of time domain detection to the signal that receives, 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 sends master sync signal and auxiliary synchronous signals on a plurality of subbands, the precision that will cause UE to detect master sync signal and auxiliary synchronous signals reduces, and then influences 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, this method comprises:

When in 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 the subcarrier on the same subband to launch each section signal to be transmitted respectively in the different unit interval, the described different unit interval is continuous each other.

As seen from the above technical solution, the present invention passes through the signal to be transmitted segmentation, in 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 on time domain, in 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 influences 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 6 the signal to be transmitted section frequency resource schematic diagram that takies.

Fig. 8 is that length is 10 the signal to be transmitted section frequency resource schematic diagram that 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, this method comprises:

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

In this step, if in 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 in a unit interval.

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

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

If in 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 in the different unit interval, utilize the effective subcarrier on the same sub-band to launch each section signal to be transmitted respectively, 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 in 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 on different time-domain resource, taking identical frequency domain resource, can either succeed in sending up signal, can guarantee the relativity of time domain energy of signal again.

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 emission again behind the time-domain signal respectively.

Particularly, transmitting terminal is converted to time-domain signal respectively 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 corresponding time-domain signal successively, add the signal of the afterbody predetermined length of the time-domain signal after connecting the head of the time-domain signal after this connection to 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, this method comprises:

Step 401, transmitting terminal is divided into the experimental process section successively with the synchronizing signal of the frequency domain form of generation, and length of each son section is no more than effective number of sub carrier wave that an OFDM symbol time is carried.

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 certain at interval sampled distance.In a radio frames, can place master sync signal earlier, auxiliary synchronous signals is placed in the back, also can place auxiliary synchronous signals earlier, places master sync signal again.

Wherein, it is for the ease of utilizing master sync signal that auxiliary synchronous signals is carried out coherent detection that master sync signal and auxiliary synchronous signals take a subband jointly, improves the coherent detection accuracy.

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

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

Step 404, transmitting terminal adds the data that are converted to the afterbody predetermined length that transmits of time domain form to transmit head, promptly 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 preceding 463 sampled points of a radio frames, and primary synchronization channel takies 462 sampled points after the auxiliary synchronization channel.

Being at 62 with the length of the master sync signal of armed frequency domain form below is example, and the described method of Fig. 4 is carried out exemplary illustration, 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, this method comprises:

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

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

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

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

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

Step 603 is 64 IFFT respectively 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, the CP head length degree that adds 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, and it is as follows to generate formula,

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

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 constitutes 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 constitutes 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 m ₀And m ₁According to cell group identification

Determine:

m ₀＝m′mod31

$m^{\′}=N_{\mathrm{ID}}^{\left(1\right)}+q(q+1)/2,$

Sequence

With

According to parameter 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 c ₀(n) and c ₁(n) can be according to sector ID and to the m sequence

The cyclic shift structure obtains:

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

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

Wherein

Represent 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 to parameter m 0 and m1 value to the m sequence Cyclic shift obtains:

$z_1^{\left(m_0\right)}\left(n\right)=\tilde{z}\left((n+\left({\mathrm{<figure-callout\; id="0"\; label="m"\; filenames="HSA00000218334700011.png,HSA00000218334700012.png"\; state="\{\{state\}\}">m</figure-callout>}}_0\mathrm{mod}8\right))\mathrm{mod}31\right)$

$z_1^{\left(m_1\right)}\left(n\right)=\tilde{z}\left((n+\left({\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HSA00000218334700011.png,HSA00000218334700022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1\mathrm{mod}8\right))\mathrm{mod}31\right)---\left(8\right)$

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, specifically see also Fig. 9 according to master sync signal and auxiliary synchronous signals.

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

As shown in Figure 9, this 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 the symbol timing estimation and sector ID detects according to the slip correlated results.Particularly, the sector ID value of choosing the alternative master sync signal correspondence with maximum related value is a testing result, and the position of writing down 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 offset estimating 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 estimation results, 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 auxilliary synchronous frequency-region signal to time-domain signal.Subscriber equipment is done coherent detection according to the domain channel response of master sync signal to auxilliary 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 determined cell set ID according to the position of the strongest relevant peaks.

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

Claims (7)

1. the signal transmitting method in the subband ofdm system more than a kind is characterized in that, this method comprises:

When in 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 the effective subcarrier on the same subband to launch each section signal to be transmitted respectively in the different unit interval, the described different unit interval is continuous each other.

2. signal transmitting method according to claim 1 is characterized in that, describedly utilizes effective subcarrier on the same subband to launch each section signal to be transmitted respectively in the different unit interval to comprise:

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.

3. signal transmitting method according to claim 2 is characterized in that, described each section of emission signal to be transmitted comprises:

The signal to be transmitted of each section frequency domain form is converted to emission again behind the time-domain signal respectively.

4. signal transmitting method according to claim 3 is characterized in that,

The signal to be transmitted of each section frequency domain form is converted to time-domain signal respectively, according to each section signal to be transmitted sequencing of shared unit interval, connect corresponding time-domain signal successively, add the signal of the afterbody predetermined length of the time-domain signal after connecting the head of the time-domain signal after this connections to as Cyclic Prefix, launch the described time-domain signal that has added described Cyclic Prefix.

5. according to the described signal transmitting method of the arbitrary claim of claim 1 to 4, it is characterized in that,

Described the signal to be transmitted segmentation is comprised:

The length of every segment signal of telling is no more than the number of all effective subcarriers that the shared subband of signal to be transmitted carries in a unit interval.

6. according to the described signal transmitting method of the arbitrary claim of claim 1 to 4, it is characterized in that,

A described unit interval is an OFDM symbol time.

7. according to the described signal transmitting method of the arbitrary claim of claim 1 to 4, it is characterized in that,

Described signal to be transmitted comprises master sync signal and auxiliary synchronous signals.

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