CN101682419A - Method of transmitting reference signal and transmitter using the same - Google Patents

Abstract

A method and apparatus of transmitting a reference signal in a wireless communication system is provided. A reference signal sequence is generated by using a pseudo-random sequence. A portion or the entirety of the reference signal sequence is mapped to at least one resource block, and is transmitted. The pseudo-random sequence is generated by a gold sequence generator which is initialized with initial values obtained by using cell identifier. The reference signal provides low PAPR and high cross correlation characteristic.

Description

Send the method for reference signal and the transmitter that adopts this method

Technical field

The present invention relates to radio communication, more specifically, relate in wireless communication system and to generate and the sequence of application reference signal.

Background technology

Wireless communication system has obtained in the whole world popularizing so that the various types of communication services such as speech or data to be provided widely.Usually, wireless communication system is to support the multiple access system that communicates with a plurality of users by sharing available system resource (for example, bandwidth, transmitted power etc.).The example of multiple access system comprises that code division multiple access inserts (CDMA) system, frequency division multiple access inserts (FDMA) system, time division multiple access access (TDMA) system, OFDM access (OFDMA) system and single-carrier frequency division multiple access and inserts (SC-FDMA) system etc.

In wireless communication system, sequence is normally used for the various uses such as reference signal, scrambler etc.The sequence that is used for wireless communication system satisfies following characteristic usually:

(1) is used to provide the good correlation properties of high detection performance.

(2) be used to increase the equal power ratio of ebb (PAPR:peak-to-average power ratio) of the efficient of power amplifier.

(3) generate a large amount of sequences to send bulk information or easily to carry out plot planning.

Although proposed to have permanent envelope zero auto-correlation (the CAZAC:constant amplitude and zero auto correlation) sequence of good PAPR characteristic, the number of available sequences is limited.Therefore, most wireless communication systems adopt the sequence that generates with pseudo-random fashion.The advantage of pseudo random sequence is to have a large amount of available sequences, but it exists in the problem of the high PAPR under the AD HOC.

Various binary systems or nonbinary pseudo random sequence have been used to wireless communication system.Pseudo random sequence can utilize m rank linear feedback shift registers (LFSR) easily to produce, and has very excellent stochastic behaviour.Because the structure of m sequence is more simple in structure than non-binary pseudo random sequence, therefore the m sequence is used as scrambler in wideband CDMA (WCDMA) system.

The Gold sequence is a pseudo random sequence of utilizing two different binary system m sequences to produce.The Gold sequence can easily produce by two m rank LFSR.The advantage of Gold sequence is and can produces different pseudorandom series according to the initial condition that the cycle changes each m rank LFSR simultaneously.

Therefore, need a kind of method that can produce sequence with improved PAPR and correlation properties.

Summary of the invention

The invention provides a kind of method and apparatus that in wireless communication system, sends reference signal.In addition, also provide a kind of receiver that is used to receive the reference signal of this transmission.

The present invention also provides a kind of method and apparatus that sends sequence in wireless communication system.In addition, also provide a kind of receiver that is used to receive the sequence of this transmission.

In one aspect, provide a kind of method that sends reference signal in wireless communication system, this method comprises the steps: to produce reference signal sequence, with the part of this reference signal sequence or all be mapped at least one RB; And be sent in reference signal among described at least one RB.This reference signal sequence is defined by following formula:

$r_{1,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is OFDM (OFDM) symbol number in the time slot, and N _RB ^{Max, DL}It is the maximum number of Resource Block (RB).Pseudo random sequence c (i) produces by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier.

This pseudo random sequence c (i) is defined by following formula,

c(i)＝(x(i+Nc)+y(i+Nc))mod?2

x(i+31)＝(x(i+3)+x(i))mod?2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod?2

Wherein, x (i) and y (i) are that m sequence and Nc are constant.Can utilize x (0)=1, x (i)=0, i=1,2 ..., 30 come m sequence x (i) is carried out initialization, and utilize described initial value that m sequence (y) is carried out initialization.Nc can be the value that is in 1500 to 1800 scopes.

Described initial value can be along with the variation of OFDM symbol number and is changed.Can utilize l (2N _ID ^Cell+ 1) obtains described initial value.The size of described initial value can be 31 bits.

A RB can comprise 12 subcarriers in frequency domain.Two modulation symbols of reference signal sequence can be mapped on two subcarriers of a RB.

Reference signal can be sub-district public reference signal or subscriber equipment (UE) DRS (Dedicated Reference Signal).

On the other hand, provide a kind of transmitter, it comprises: reference signal generator, and it produces reference signal; And radiating circuit, it sends described reference signal.Described reference signal generator produces described reference signal by producing by the defined reference signal sequence of following formula:

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, and N _RB ^{Max, DL}It is the maximum number of RB.Pseudo random sequence c (i) produces by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier; Described reference signal generator is with the part of described reference signal sequence or all be mapped at least one RB.

More on the one hand, a kind of receiver is provided, this receiver comprises: receiving circuit, it receives reference signal and received signal; Channel estimator, it utilizes described reference signal to estimate channel; And data processor, it utilizes described channel to handle described received signal.Described reference signal produces based on the reference signal sequence by the following formula definition:

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, and N _RB ^{Max, DL}It is the maximum number of RB.Pseudo random sequence c (i) produces by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier.

The sequence that is proposed provides equal power ratio of ebb (PAPR) and high their cross correlation.Therefore, transmitted power can be provided effectively, and signal detection performance can be improved at the receiver place at the transmitter place.The sequence of this proposition can be used for the reference signal of requirement high reliability and can be used to other scramblers.

Description of drawings

Fig. 1 shows wireless communication system.

Fig. 2 shows the structure of radio frames among the 3GPP LTE.

Fig. 3 shows the example of the resource grid of a downlink time slots.

Fig. 4 shows the exemplary configurations of downlink subframe.

Fig. 5 shows when BS adopts an antenna, the exemplary configurations of down link public reference signal.

Fig. 6 shows when BS adopts two antennas, the exemplary configurations of down link public reference signal.

Fig. 7 shows when BS adopts four antennas, the exemplary configurations of down link public reference signal.

Fig. 8 shows the example of Gold sequencer.

Fig. 9 shows the setting of the initial value of the 2nd LFSR.

Figure 10 is when the initial value of the 2nd LFSR all is set to " 0 ", the figure of the size of comparison reference signal and any data.

Figure 11 shows in many cell environments the problem that the initial value by the Gold sequence causes.

Figure 12 shows the example that the bit sequence that is recycled mapping in the QPSK modulation is set as initial value.

The initial value that Figure 13 shows a LFSR is set as the example of 1 complement code of the initial value of the 2nd LFSR.

The skew that Figure 14 shows available sequences changes according to sub-district ID.

The basic sequence that Figure 15 shows use carries out cyclic shift according to sub-district ID.

Figure 16 shows the starting point of using sequence and number changes according to subframe numbers and/or OFDM symbol.

Figure 17 shows the setting of the initial value of Gold sequencer.

Figure 18 is the flow chart that illustrates according to the method for the transmission reference signal of an embodiment of the invention.

Figure 19 is the block diagram that the transmitter and receiver of the method that has realized transmission and received reference signal is shown.

Embodiment

The technology of introducing below can be used for inserting such as code division multiple access the various wireless access technologys of (CDMA), frequency division multiple access access (FDMA), time division multiple access access (TDMA), OFDM access (OFDMA) and single-carrier frequency division multiple access access (SC-FDMA) etc.CDMA can realize by the wireless technology such as general land wireless access (UTRA) or CDMA2000.TDMA can realize by the wireless technology such as global system for mobile communications (GSM)/GPRS (GPRS)/enhancing data transfer rate GSM evolution (EDGE).OFDMA can realize by the wireless technology such as IEEE (IEEE) 802.11 (Wi-Fi), IEEE802.16 (WIMAX), IEEE802-20, evolved UTRA (E-UTRA) etc.UTRA is the part of Universal Mobile Telecommunications System (UMTS).Third generation partner program (3GPP) Long Term Evolution (LTE) is a part that adopts the evolved UMTS (E-UMTS) of E-UTRA.3GPP LTE adopts OFDMA in down link, and adopts SC-FDMA in up link.Enhancement mode LTE (LTE-A) is the evolution of 3GPP LTE.

For simplicity, following introduction will concentrate on 3GPP LTE/LTE-A.But technical characterictic of the present invention is not limited thereto.

Fig. 1 shows wireless communication system.

With reference to Fig. 1, wireless communication system 10 comprises at least one base station (BS) 11.Base station 11 provides communication service to specific geographic area (so-called sub-district) 15a, 15b and 15c.The sub-district can be divided into a plurality of zones (being called the sector).Subscriber equipment (UE) 12 can be fixed or move, and subscriber equipment (UE) 12 can be called other term (as mobile radio station (MS), user terminal (UT), subscriber station (SS), wireless device, PDA(Personal Digital Assistant), radio modem, handheld device etc.).BS 11 is generally the fixed station of communicating by letter with user UE 12, and can be known as other term (as evolved Node B (eNB), base station transceiver communication system (BTS), access point etc.).

Hereinafter, down link is meant the communication link from BS to UE, and up link is meant the communication link from UE to BS.In down link, transmitter can be the part of BS, and receiver can be the part of UE.In up link, transmitter can be the part of UE, and receiver can be the part of BS.

Fig. 2 shows the wireless frame structure among the 3GPP LTE.

With reference to Fig. 2, radio frames comprises 10 subframes.A subframe comprises 2 time slots.With the timing definition that sends a subframe is Transmission Time Interval (TTI:transmission time interval).For example, the length of a subframe can be 1 millisecond (ms), and the length of a time slot can be 0.5ms.

A time slot comprises a plurality of OFDMs (OFDM) symbol in time domain.Because 3GPPLTE uses OFDMA in down link, so the OFDM symbol is used for representing a symbol period.According to system, the OFDM symbol can also be known as SC-FDMA symbol or symbol period.Resource Block (RB) is a resource allocation unit, and is included in a plurality of continuous sub-carriers in the time slot.

The wireless frame structure that illustrates is the purpose of property presented for purpose of illustration only.Therefore, the OFDM symbol numbers that comprises in number of time slots that comprises in number of sub-frames that comprises in the radio frames or the subframe or the time slot can be made amendment by variety of way.

Fig. 3 shows the resource grid of a downlink time slots.

With reference to Fig. 3, downlink time slots comprises a plurality of OFDM symbols in time domain.Be here exemplified with a downlink time slots and comprise 7 OFDM symbols, and a Resource Block (RB) comprises 12 subcarriers in frequency domain.But, the invention is not restricted to this.

Each unit in the resource grid is known as Resource Unit.A RB comprises 12 * 7 Resource Units.The number N of the RB that comprises in the downlink time slots ^DLDepend on that down link sends bandwidth.

Fig. 4 shows the exemplary configurations of downlink subframe.

With reference to Fig. 4, subframe comprises two time slots.Maximum 3 the OFDM symbols of previous section of first time slot that are positioned at subframe are corresponding to the control area that is assigned control channel.Remaining OFDM symbol is corresponding to the data area that is assigned physical down link sharing channel (PDSCH).

The example of the downlink control channel that uses among the 3GPP LTE comprises Physical Control Format Indicator Channel (PCFICH), physical downlink control channel (PDCCH), physical mixed ARQ indicating channel (PHICH) etc.PCFICH is first OFDM symbol transmission in subframe, and carries the information about the OFDM symbol numbers that is used to transmit control channel in subframe.The control information that sends via PDCCH is known as down link control information (DCI).DCI comprises up link or downlink schedule information or comprises the up-link transmit power control command that is used for any UE group.

Now, reference signal is described.

When sending data in wireless communication system, sending data might distortion on wireless channel.In order to make receiver the data of distortion can be reverted to initial data, channel status need be known so that distortion to received signal compensates according to channel status.In order to know channel status, adopted at all known in advance signal of transmitter and receiver.Sort signal is known as reference signal or pilot tone.Because reference signal is the signal of interest that is used for understanding channel status, so transmitter uses the transmitting power bigger than other signals to send reference signal.In addition, in order to distinguish the reference signal that sends in the minizone in many cell environments, reference signal must have good peak-to-average power ratio (PAPR) and correlation properties.

Reference signal can be divided into sub-district public reference signal and UE DRS (Dedicated Reference Signal).The reference signal that the sub-district public reference signal is used by all UE in the sub-district.The UE DRS (Dedicated Reference Signal) is by the reference signal of the use of the UE in the sub-district or UE group's use.

Fig. 5 illustrates when BS adopts an antenna, the exemplary configurations of down link public reference signal.Fig. 6 illustrates when BS adopts two antennas, the exemplary configurations of down link public reference signal.Fig. 7 illustrates when BS adopts four antennas, the exemplary configurations of down link public reference signal.These contents can be at the 6.10.1 of 3GPP TS 36.211 V8.0.0 (2007-09) part " Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channelsand modulation (Release 8) " in find.Rp represent to be used for p root antenna reference signal (herein, p ∈ 0,1,2,3}).R0 to R3 is crossover not each other.In an OFDM symbol, each Rp is set with the spacing of 6 subcarriers.Therefore, if a RB comprises 12 subcarriers, then to need length be the sequence of two sequences (or two modulation symbols) to a RB.In subframe, the number of R0 equals the number of R1, and the number of R2 equals the number of R3.In subframe, the number of R2 and R3 is less than the number of R0 and R1.Do not use Rp in the transmission via other antennas beyond the p root antenna, this is for fear of the interference between antenna.

Now, the generation to the sequence of reference signal describes.

Consider to adopt the reference signal of Gold sequencer generation.The Gold sequence can realize by two 31 rank linear feedback shift registers (LFSR).Suppose LFSR ' x (30) x (29) x (28) among two LFSR ... x (2) x (1) x (0) ' carries out initialization with ' 0000000000000000000000000000001 '.In addition, the initial value of the 2nd LFSR is determined by cell identifier (ID), subframe numbers and OFDM symbol number.Sub-district ID represents cell-specific ID.Subframe numbers is represented the index of subframe in the radio frames.The index of the OFDM symbol number interior OFDM symbol of expression subframe (or time slot).

Fig. 8 illustrates the example of Gold sequencer.Sequence generator polynomial D ³¹+ D ³+ 1 is used for a m sequence x (i), and sequence generator polynomial D ³¹+ D ³+ D ²+ D+1 is used for the 2nd m sequences y (i).These two m sequences are used to produce pseudo random sequence c (i).This pseudo random sequence c (i) is produced by the generator polynomial that is depicted as equation 1:

[equation 1]

c(i)＝(x(i)+y(i))mod?2

x(i+31)＝(x(i+3)+x(i))mod?2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod?2

Wherein, i=0,1 ..., M _Max-1, and M _MaxBe the length of utilizing the binary pseudo-random sequence of Gold sequence generation.Has M _MaxIn the pseudo random sequence of length, can only use the part of sequence.If M only uses to have M _MaxThe sequence length of the part of the pseudo random sequence of length, then M≤M _MaxM can change according to the number of the RB that is used for the data transmission.Available RB number changes according to the available band in the 3GPP LTE system, therefore is worth M and also can changes according to the number of the RB that is distributed.

Under the situation of a LSFR, as mentioned above, initial value is fixed to ' 0000000000000000000000000000001 '.The initial value of the 2nd LFSR is determined by sub-district ID, subframe numbers and OFDM symbol number.

Fig. 9 shows the setting of the initial value of the 2nd LFSR.In the initial value of 31 bits, number come 17 bits from least significant bit (LSB) beginning are carried out initialization with the OFDM symbol of the subframe numbers of the sub-district ID of 9 bits, 4 bits and 4 bits.3GPP LTE supports 504 unique sub-district ID, so the scope of sub-district ID is from 0 to 503.A radio frames comprises 10 subframes, so the scope of subframe numbers is from 0 to 9.A subframe can comprise 14 OFDM symbols of as many as, so the scope of OFDM symbol number is from 0 to 13.Can carry out initialization to residue 14 bits with ' 0 ' from highest significant position (MSB) beginning.The initial value of the 2nd LFSR can be represented with following table.

[table 1]

In the superincumbent table 1, the scope of sub-district ID, OFDM symbol number and subframe numbers and/or number of bits are not limited to this just for the purpose of example.For example, subframe numbers can be represented with timeslot number, because radio frames comprises 20 time slots, so the scope of timeslot number can be 0 to 19.

After the initial value of the initial value of having determined a LFSR and the 2nd LFSR, the part of the pseudo random sequence that produces by the Gold sequencer or all be used as reference signal.The sequence that is produced is modulated into modulation symbol via quarternary phase-shift keying (QPSK) (QPSK) modulation, is mapped to each Resource Unit then.In this case, can only use the part of the Gold sequence of the specific dimensions that produces in advance.For example, as shown in Figure 5, in 12 subcarriers that constitute a RB, reference signal can be mapped in two subcarriers with 6 sub-carrier separation.

But, when producing pseudo random sequence as mentioned above, in the binary pseudo-random sequence that is produced, might not to comprise ' 0 ' and ' 1 ' with similar ratio, therefore ' 0 ' number may be greater than ' 1 ' number, and perhaps ' 1 ' number may be greater than ' 0 ' number.In this case, even carry out the QPSK modulation, also can there be direct current (DC) component owing to the pseudo random sequence of biasing.Consequently, handle through invert fast fourier transformation (IFFT), the PAPR characteristic might worsen.As representational example, if sub-district ID, subframe numbers and OFDM symbol number all are ' 0 ', then 31 bits of the initial value of the 2nd LFSR all are set to ' 0 '.

Figure 10 is when the initial value of the 2nd LFSR all is set to " 0 ", the figure of the size of comparison reference signal and arbitrary data.When 31 bits of the initial value of Gold sequencer all use ' 0 ' to carry out initialization, produced the reference signal that has much larger than the size of any other data in some time samplings place, this means that the PAPR characteristic descends.

Figure 11 is illustrated in many cell environments the problem that the initial value by the Gold sequence causes.In many cell environments, each sub-district has unique sub-district ID.Therefore but if remaining 22 bits are identical, then because have only 9 bit differences in 31 bits of initial value, the pseudo random sequence that produces at each sub-district much at one.Particularly, if sub-district ID is continuous in each sub-district, then nearly 30 bits may crossover in 31 bits of initial value.Therefore, when pseudo random sequence that this produced was used as reference signal, correlation properties might worsen.

Below, introduce the generation of sequence and to the application of the sequence that produced, to address the above problem.

At first, introduction produces the method for sequence by the highest significant position (MSB) of the initial value of change Gold sequence.

When adopting the Gold sequence to produce pseudo random sequence, will become suitable value from 14 bits that MSB begins so that ' 0 ' and ' 1 ' the ratio that is comprised the initial value of the 2nd LFSR equates.Because in some cases, sub-district ID, subframe numbers and OFDM symbol number might all be set to ' 0 ', therefore remaining 14 bits are become suitable value has good PAPR characteristic with definition Gold sequence.Under the situation of using the Gold sequence, the pseudo random sequence that is generated is determined according to initial value.Therefore, it is most important to the sequence that generation has good PAPR initial value to be set.

In one embodiment, 14 bits that begin from MSB all can be set to ' 1 '.By doing like this, can prevent that the initial value of Gold sequence all is set to ' 0 ', thereby can avoid the deterioration of PAPR characteristic.Table 2 shows the PAPR in the time will all being set to ' 0 ' from 14 bits that MSB begins.Table 3 shows the PAPR in the time will all being set to ' 1 ' from 14 bits that MSB begins.In table 2 and table 3, show when the reference signal of using is the basic sequence that produces by 17 bits that begin from LSB that the Gold sequencer number differently is set according to sub-district ID, subframe numbers and OFDM symbol peak value at RB number (, 6,12,25,50 and 100).

[table 2]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00000000000000	??10000110000100110	??1.06	??1.89
??12	??00000000000000	??10000011010110011	??1.33	??2.36
					??25	??00000000000000	??00000000000000000	??2.18	??3.71
??50	??00000000000000	??00000000000000000	??5.16	??8.81
					??100	??00000000000000	??00000000000000000	??10.60	??18.10

[table 3]

??RB	??MSB	??LSB	Peak value	??PAPR
					??6	??11111111111111	??10110000011101000	??0.93	??1.66
??12	??11111111111111	??10110101111110010	??1.28	??2.28
					??25	??11111111111111	??10110110110110110	??1.53	??2.61
??50	??11111111111111	??10010100100100100	??1.87	??3.19
					??100	??11111111111111	??00000000000000010	??2.49	??4.25

Shown in table 2 and table 3,14 bits that the PAPR characteristic in the time of will all being set to ' 0 ' from 14 bits that MSB begins is better than beginning from MSB all are set to ' 1 ' situation.

In another embodiment, 14 bits that begin from MSB can be arranged to be mapped to circularly the bit sequence of QPSK constellation.Identical from the sequential value of the initial output of Gold sequencer with initial value.Therefore, when initial value is arranged in 4 character positions of QPSK constellation equably, can prevent that the modulation symbol of the pseudo random sequence that produced from concentrating on specific QPSK modulation symbol.

Figure 12 shows the example that the bit sequence that is recycled mapping in the QPSK modulation is set as initial value.Suppose that 1., 2., 3. and 4. the bit sequence ' 00 ', ' 01 ', ' 11 ' and ' 10 ' in the QPSK constellation corresponds respectively to modulation symbol.Bit sequence is arranged so that 4 modulation symbols appear at equably from 14 bits that MSB begins.At first, define first bit sequence ' 00011110000111 ' so that modulation symbol with 1., 2., 3., 4., 1., 2., 3. order occurs.In fact, therefore the output of Gold sequencer, define second bit sequence ' 11100001111000 ' by first bit sequence is inverted from LSB.17 bits that begin from LSB are configured to the value number determined according to sub-district ID, subframe numbers and OFDM symbol, and a QPSK modulation symbol is made up of 2 bits.Therefore, by to second bit sequence left cyclic shift 1 bit produce the 3rd sequence ' 11000011110001 '.14 bits that begin from MSB, be provided with randomly from the nearest bit of 17 bits that begins from LSB, and next bit (that is the 19th bit that begins from LSB) that will this nearest bit is that unit is mapped to a modulation symbol with two bits.Thereby, if begin to export modulation symbol from LSB, then under the situation of the 3rd sequence, with 1., 2., 3., 4., 1., 2. order output modulation symbol.

Table 4 illustrates when 14 bits of MSB are set to ' 11000011110001 ', according to the characteristic of the PAPR of RB number.

[table 4]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??11000011110001	??10110000010110111	??0.96	??1.71
??12	??11000011110001	??01100100010101001	??1.31	??2.33
					??25	??11000011110001	??01110101011011011	??1.42	??2.42
??50	??11000011110001	??01111001101100100	??1.70	??2.90
					??100	??11000011110001	??00110000011001010	??2.06	??3.52

As shown in table 4, when 14 bits that begin from MSB were set to the proposal value, the PAPR characteristic was improved.

In another embodiment, the various combinations of 14 bits that begin from MSB have been proposed to improve the PAPR characteristic.14 bits that begin from MSB can be become ' 11111111111111 ' by ' 00000000000000 ', with find have at might situation the value of preferred PAPR characteristic, this will cause huge complexity.The number of supposing RB herein is 6,12,25,50 or 100, and the reference signal of using is the sequence with length corresponding with the RB number.For each RB number, 17 bits that begin from LSB number differently are set according to sub-district ID, subframe numbers and OFDM symbol.Reference signal is used for the IFFT computing of OFDM modulation, and if surpass specific threshold value as the peak value of the OFDM symbol of time-domain signal, then from the candidate, removed this OFDM symbol.

Table 5 illustrates 14 bits that begin from MSB that have best PAPR characteristic at each RB number (that is, 6,12,25,50 and 100).

[table 5]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00010001110001	??00000001110000010	??0.89	??1.58
??12	??11001100100000	??01000110110110101	??1.10	??1.96
					??25	??01011111100110	??00000011011100011	??1.28	??2.19
??50	??01100110010101	??00010110100100101	??1.42	??2.42
					??100	??00100001000101	??01100100011010000	??1.44	??2.46

When 14 bits that the number according to each RB is beginning from MSB during the preferred value shown in the employing table 5, can prevent the increase of the PAPR that causes owing to biasing.

Table 6 shows when at peak value and the PAPR of 14 bits when (that is, ' 00010001110001 ') that begins from MSB in each RB number employing table 5.As seen, when the preferred value at specific RB number is used to the RB of different numbers, what this preferred value may not be for optimum.

[table 6]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00010001110001	??00000001110000010	??0.89	??1.58
??12	??00010001110001	??01000011010101011	??1.50	??2.67
					??25	??00010001110001	??01000000010110001	??1.51	??2.58
??50	??00010001110001	??10110011000011001	??1.68	??2.86
					??100	??00010001110001	??00010100111100111	??1.75	??2.99

In order to be chosen as preferred value, it is vital having unified PAPR characteristic in a plurality of RB.When preferred value is set to be no more than in the value of certain threshold level when having the value of minimum peak value sum at each RB, 14 bits ' 00111101101100 ' that begin from MSB are chosen as preferred value.Table 7 illustrates as peak value and the PAPR of 14 bits when (that is, ' 00111101101100 ') that begins from MSB at each RB number employing table 7.

[table 7]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00111101101100	??01100011010011001	??0.89	??1.59
??12	??00111101101100	??00001000101010101	??1.14	??2.03
					??25	??00111101101100	??00000111111001000	??1.40	??2.40
??50	??00111101101100	??01001001010101000	??1.55	??2.65
					??100	??00111101101100	??10010011111001000	??1.56	??2.66

Compare with the result who is regarded as optimum table 5, PAPR characteristic variation, still, (that is, ' 00010001110001 ' result of) table 6 compares, and the result of its PAPR characteristic is better with adopting 14 bits that begin from MSB.Thereby peak value and PAPR characteristic are unified generally.Correspondingly, complexity can be lower than the situation that number according to RB differently adopts 14 bits that begin from MSB, and has the advantage that reduces memory-size.

The initial value of having introduced the 2nd LFSR by the Gold sequencer is set above improves the method for PAPR characteristic.To introduce the method for improving the PAPR characteristic of sequence by the initial value that a LFSR is set below.

In one embodiment, the initial value of a LFSR may be defined as particular value.For example, can be set to initial value by following bit sequence, that is, wherein modulation symbol can be mapped as this bit sequence equably on the QPSK constellation.If bit sequence ' 00 ', ' 01 ', ' 11 ' and ' 10 ' sorts with being inverted (this is because at first export LSB in the Gold sequence), and repeat mapping up to reaching 31 bits, resulting value is ' 1111000011110000111100001111000 '.Table 8 shows when the initial value of a LFSR is ' 1111000011110000111100001111000 ', according to the peak value and the PAPR of the initial value of the number of RB and a LFSR.Compare with the result of table 2, PAPR reduces significantly.

[table 8]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00000000000000	??00000011110010000	??0.95	??1.69
??12	??00000000000000	??01110010110011100	??1.16	??2.07
					??25	??00000000000000	??01110001110001110	??1.77	??3.02
??50	??00000000000000	??01100010011001001	??1.86	??3.18
					??100	??00000000000000	??10010111111011000	??1.74	??2.97

In another embodiment, initial value that can a LFSR is set to 1 complement code of the initial value of the 2nd LFSR.The initial value that Figure 13 shows a LFSR is set as the example of 1 complement code of the initial value of the 2nd LFSR.Even the initial value of the 2nd LFSR of Gold sequencer all is set to ' 0 ', the initial value of a LFSR all is configured to 1 complement code of the initial value of the 2nd LFSR.Therefore, can produce sequence, therefore can prevent the deterioration of PAPR characteristic with more stochastic behaviours.Result when table 9 shows initial value as a LFSR and is set to 1 the complement code of initial value of the 2nd LFSR.

[table 9]

The RB number	??MSB	??LSB	Peak value	??PAPR
					??6	??00000000000000	??00000000000001000	??0.97	??1.72
??12	??00000000000000	??00010001010101010	??1.27	??2.26
					??25	??00000000000000	??00010101010101010	??2.22	??3.78
??50	??00000000000000	??01110001110001110	??2.98	??5.08
					??100	??00000000000000	??00010100100000110	??3.91	??6.68

Simultaneously, in order to distinguish reference signal between minizone and UE, reference signal must have good correlation properties.Figure 11 is described as reference, and in the initial value of Gold sequencer, if having only different and other values of sub-district ID (that is, subframe numbers and OFDM symbol number) identical, then the pseudo random sequence that is produced is at some cycles crossover equally.The reason that this thing happens is to have only the value difference of 9 bits of initial value in 31 bits of initial value.Can solve this problem by considering the following fact, that is, only with the part of the sequence that produced as reference signal.This is because be M even produced length _MaxPseudo random sequence (this sequence is known as basic sequence), but use length to be the sequence of M (this sequence is known as and uses sequence) according to the number of RB.Therefore, if from the basic sequence that produces according to sub-district ID, select to use sequence, then might solve because the problem of the sequence that initial value much at one brings crossover on the part cycle by different skews.

Now, introduce the method that sequence offset is set according to sub-district ID.

Suppose that basic sequence length is M _Max, that is, basic sequence c (i) (i=0,1 ..., M _Max-1) produces by the Gold sequencer, adopt the use sequence of length M then.In this case, M≤M _MaxThe skew (that is, using the starting point of sequence) of using sequence differently is set according to sub-district ID.

The skew that Figure 14 shows available sequences changes according to sub-district ID.Here, according to sub-district ID in length M _MaxBasic sequence in be provided with and have the skew that spacing is N, and to select length be the use sequence of M.When surpassing the scope of basic sequence, this use sequence is carried out cyclic shift.According to basic sequence c (i) (i=0,1 ..., M _Max-1), use sequence cu (i) (i=0,1 ..., M-1) can be expressed as follows:

[equation 2]

$\mathrm{cu}\left(i\right)=c\left((i+N\&CenterDot;N_{\mathrm{ID}}^{\mathrm{cell}})\mathrm{mod}(M_{\max }-1)\right)$

Wherein, ' mod ' is for asking modular arithmetic, the interval of N for being offset, and N _ID ^CellBe sub-district ID.Though defined identical skew at each sub-district ID herein, this just for exemplary purposes therefore can be at the different skew of each sub-district ID definition.

By changing the starting point of using sequence, even make that the use sequence also can be different under the similar situation of initial value according to sub-district ID.Therefore, stochastic behaviour can be guaranteed, and the PAPR characteristic degradation can be prevented.

Above-mentioned equation 2 can be that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and illustrates with following equation:

[equation 3]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

$a_{k,l}^{\left(p\right)}=r_{l,n_s}\left(m^{\&prime;}\right)$

$m=\mathrm{0,1}...,2\&CenterDot;N_{\mathrm{RB}}^{\mathrm{DL}}-1$

$m^{\&prime;}=(m+N_{\mathrm{Interval}}^{\mathrm{RS}}{N}_{\mathrm{ID}}^{\mathrm{cell}})\mathrm{mod}(2\&CenterDot;N_{\mathrm{RB}}^{\max ,\mathrm{DL}-1})$

Here, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, r _{L, ns}Be reference signal sequence, N _RB ^{Max, DL}Be the maximum number of RB, m is the index of reference signal sequence, and m ' is the index that is used to get the part of reference signal sequence, N _RB ^DLThe number of the RB that is to use, α _{K, l}(p) be at time slot n _sBe used as the modulation symbol at the reference symbol of p root antenna port, k is the sub-carrier indices that is used to send reference signal, and N _RS ^{Int erval}Be based on sub-district IDN _Cell ^IDThe interval of starting point, r _{L, ns}(m) be basic sequence, and r _{L, ns}(m ') is to use sequence.

Figure 15 shows the basic sequence of use according to sub-district ID cyclic shift.Producing length by the Gold sequencer is M _MaxBasic sequence (that is, and basic sequence c (i) (i=0,1 ..., M _Max-1)).According to sub-district ID determine cyclic shift amount N thereafter.Then, basic sequence is recycled the cyclic shift amount N that has been shifted.In this case, use the starting point of sequence can always be placed on identical position.According to basic sequence c (i) (i=0,1 ..., M _Max-1), use sequence cu (i) (i=0,1 ..., M-1) can represent by following equation:

[equation 4]

$c_{\mathrm{shift}}\left((i+N\&CenterDot;N_{\mathrm{ID}}^{\mathrm{cell}})\mathrm{mod}(M_{\max }-1)\right)=c\left(i\right)$

cu(i)＝c _shift(i)

Wherein, c _Shift(i) be by to the basic sequence cyclic shift sequence that obtains of cyclic shift amount N.

Above-mentioned equation 4 can be that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and illustrates with following equation:

[equation 5]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

$a_{k,l}^{\left(p\right)}=r_{l,n_s}\left(m^{\&prime;}\right)$

$m=\mathrm{0,1}...,2\&CenterDot;N_{\mathrm{RB}}^{\mathrm{DL}}-1$

$m^{\&prime;}=(m+N_{\mathrm{Interval}}^{\mathrm{RS}}{N}_{\mathrm{ID}}^{\mathrm{cell}}+N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-N_{\mathrm{RB}}^{\mathrm{DL}})\mathrm{mod}(2\&CenterDot;N_{\mathrm{RB}}^{\max ,\mathrm{DL}-1})$

In another embodiment, when producing pseudo random sequence, can get rid of some sequences of initial generation by the Gold sequencer.The sequence that can be Nc with length is removed from the Gold sequence of initial generation, and sequence subsequently can be used as reference signal sequence.Therefore initial value has very big influence to the sequence of initial generation, can avoid the deterioration of the PAPR characteristic that caused by similar initial value.This can represent by following equation:

[equation 6]

c′(i)＝c(i+Nc)

Above-mentioned equation 6 can be represented with the form of above-mentioned equation 1, and be depicted as following equation:

[equation 7]

c(i)＝(x(i+Nc)+y(i+Nc))mod?2

x(i+31)＝(x(i+3)+x(i))mod?2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod?2

Value Nc can be arranged to the length of generation fully at random, make the pseudo random sequence that is produced not be subjected to the influence of initial value.For example, value Nc can be in 1500 to 1800 scope.

Above-mentioned equation 7 can be by utilizing pseudo random sequence c (i), is that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and illustrates with following equation:

[equation 8]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

$a_{k,l}^{\left(p\right)}=r_{l,n_s}\left(m^{\&prime;}\right)$

$m=\mathrm{0,1}...,2\&CenterDot;N_{\mathrm{RB}}^{\mathrm{DL}}-1$

$m^{\&prime;}=m+N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-N_{\mathrm{RB}}^{\mathrm{DL}}$

Now, the their cross correlation between the pseudo random sequence of introduction generation.

The pseudo random sequence G (D) that utilizes two m sequence X (D) and Y (D) to produce can represent with following polynomial form:

[equation 9]

G(D)＝c ₀+c ₁D+c ₂D ²+...

$G\left(D\right)=X\left(D\right)\&CirclePlus;Y\left(D\right)$

Here, a m sequence X (D) is I ₁(D)/g ₁(D), the 2nd m sequence Y (D) is I ₂(D)/g ₂(D).g ₁(D) and g ₂(D) be the primitive polynomial (primitive polynomials) that is used to produce X (D) and Y (D), and be defined as follows:

[equation 10]

g ₁(D)＝1+D ^-3+D ^-31

g ₂(D)＝1+D ^-1+D ^-2+D ^-3+D ^-31

I ₁(D) and I ₂(D) be the initial value that is used to produce X (D) and Y (D), and define by following equation:

[equation 11]

I ₁(D)＝1

$I_2\left(D\right)=I\left(\mathrm{CELLID}\right)\&CirclePlus;I\left(N_{\mathrm{sf}}\right){\mathrm{<figure-callout\; id="9"\; label="D"\; filenames="A2009800000670037H1.png,A2009800000670040H1.png"\; state="\{\{state\}\}">D</figure-callout>}}^9$

Here, I (CELLID) is the initial value according to sub-district ID (CELLID), and I (N _Sf) D ⁹It is initial value according to timeslot number and OFDM symbol number.

In the regularly identical synchronous environment in a plurality of minizones, neighbor cell has identical timeslot number and identical OFDM symbol number.If suppose to use identical timeslot number and identical OFDM symbol number, the cross-correlation between the pseudo random sequence that produces in having two neighbor cells of different districts ID CELLID1 and CELLID2 can obtain by following equation:

[equation 12]

$G_1\left(D\right){\&CirclePlus;G}_2\left(D\right)=X\left(D\right)\&CirclePlus;Y_1\left(D\right)\&CirclePlus;X\left(D\right){\&CirclePlus;Y}_2\left(D\right)$

$=Y_1\left(D\right){\&CirclePlus;Y}_2\left(D\right)$

$=I_{2,\mathrm{cell}1}\left(D\right)/g\left(D\right)\&CirclePlus;I_{2,\mathrm{ecll}2}\left(D\right)/g\left(D\right)$

$=[I\left(\mathrm{CELLID}1\right)\&CirclePlus;I\left(N_{\mathrm{sf}}\right)D^9]/g\left(D\right)\&CirclePlus;[I\left(\mathrm{CELLID}2\right)\&CirclePlus;I\left(N_{\mathrm{sf}}\right)D^9]/g\left(D\right)$

$=I\left(\mathrm{CELLID}1\right)/g\left(D\right)\&CirclePlus;I\left(N_{\mathrm{sf}}\right){\mathrm{<figure-callout\; id="9"\; label="D"\; filenames="A2009800000670037H1.png,A2009800000670040H1.png"\; state="\{\{state\}\}">D</figure-callout>}}^9/g\left(D\right)\&CirclePlus;I\left(\mathrm{CELLD}2\right)/g\left(D\right)\&CirclePlus;I\left(N_{\mathrm{sf}}\right){\mathrm{<figure-callout\; id="9"\; label="D"\; filenames="A2009800000670037H1.png,A2009800000670040H1.png"\; state="\{\{state\}\}">D</figure-callout>}}^9/g\left(D\right)$

$=I\left(\mathrm{CELLID}1\right)/g\left(D\right)\&CirclePlus;I\left(\mathrm{CELLID}2\right)/g\left(D\right)$

Above-mentioned equation shows: their cross correlation is only determined by sub-district ID.Because according to the variation in timeslot number and the OFDM symbol number, the their cross correlation of minizone does not change, and therefore utilizes this method to be difficult to obtain to have the sequence of good their cross correlation.

When at two sub-districts, the modulation sequence that the modulation symbol that will obtain by the pseudo random sequence that produces is carried out the QPSK modulation is formed is expressed as R1[n respectively] and R2[n] time, the sequence after the modulation can be represented by following equation:

[equation 13]

R1[n]＝S[2n]X1[2n]+jS[2n+1]X1[2n+1]

R2[n]＝S[2n]X2[2n]+jS[2n+1]X2[2n+1]

Wherein, S[n] be the sub-district common sequence that depends on subframe numbers and OFDM symbol number, and X1[n] and X2[n] be the cell-specific sequence that obtains according to each sub-district ID.Above-mentioned sequence R1[n] and R2[n] cross-correlation can obtain by following equation:

[equation 14]

R1[n]R2[n] ^*＝(S[2n]X1[2n]+jS[2n+1]X1[2n+1])(S[2n]X2[2n]+jS[2n+1]X2[2n+1]) ^*

＝X1[2n]X2[2n] ^*+X1[2n+1]X2[2n+1] ^*+j(S[2n+1]X1[2n+1]S[2n] ^*X2[2n] ^*

-S[2n+1]X2[2n+1]S[2n] ^*X1[2n] ^*)

Wherein, () ^*The expression complex conjugate.Two modulation sequence R1[n] and R2[n] the result of cross-correlation show: on the Q axle, have sub-district common sequence component and do not change, and this sub-district common sequence component is removed on the I axle, and wherein said sub-district common sequence component is along with the variation of subframe numbers and OFDM symbol number and change.Therefore, be difficult in the minizone and obtain good their cross correlation.

Therefore, a kind of method of improving the their cross correlation between the pseudo random sequence that is produced is proposed.

In one embodiment, use the starting point of sequence number to change according to subframe numbers and/or OFDM symbol.Figure 16 illustrates the starting point of using sequence and number changes according to subframe numbers and/or OFDM symbol.Produce long pseudo random sequence according to each sub-district ID.Number obtain to support a plurality of basic sequences of the RB of maximum number according to subframe numbers and OFDM symbol from long pseudo-random code sequence, each basic sequence length is M _MaxObtaining length from basic sequence is use sequence M, that be used to send actual reference signal.Therefore, can improve the their cross correlation of the reference signal of minizone.

Reference sequences can be that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and illustrates with following equation:

[equation 15]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+l^{\&prime;}))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1+l^{\&prime;})),$

$l^{\&prime;}=4N_{\mathrm{RB}}^{\max ,\mathrm{DL}}\&CenterDot;(N_{\mathrm{symb}}^{\mathrm{DL}}\&CenterDot;n_s+l)$ And $m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, r _{L, ns}Be reference signal sequence, N _RB ^{Max, DL}Be the maximum number of RB, m is the index of reference signal sequence, N _Symb ^DLIt is OFDM symbol numbers included in the time slot.Section start at each OFDM symbol utilizes N _ID ^CelL+1 carries out initialization to the basic sequence c (i) that produces by the Gold sequencer.

In another embodiment, can change the initial value that when generating basic sequence, uses to improve their cross correlation.If between a plurality of sub-districts in the regularly identical synchronous environment, subframe numbers and/or OFDM symbol are number identical, depend on that then the initial value of subframe numbers and/or OFDM symbol number is similar in the minizone, and this will cause relatively poor correlation properties.In addition, in asynchronous environment, the transmitting time difference between needs consideration neighbor cell is so that initial value is identical discontinuously.

Initial value can differently change according to the variation of the subframe numbers of minizone and/or OFDM symbol number.For example, can dispose first sub-district so that initial value along with the increase of OFDM symbol number and increase or reduce, and can dispose second sub-district so that initial value along with the increase of OFDM symbol number and increase or reduce.For example, allocating cell ID is that the sub-district of CELLID1 is so that along with number increase by 1 of OFDM symbol, initial value increases n.In addition, allocating cell ID is that the sub-district of CELLID2 is so that along with number increase by 1 of OFDM symbol, initial value increases n+1.

Can be unit with the radio frames rather than existingly in subframe or time slot, the OFDM symbol number is expanded, thereby initialized variation be along with the variation of OFDM symbol number and difference.If there is N in each subframe _SymIndividual OFDM symbol, then q OFDM symbol of the k subframe of radio frames number can be expressed as k*N _Sym+ q.

In the system that the number of the OFDM symbol that each subframe comprises changes, can be at the maximum number N of the OFDM symbol that comprises in each subframe _{Sym, max}Define.In this case, q OFDM symbol of the k subframe of radio frames number can be expressed as k*N _{Sym, max}+ q.The reason of above-mentioned way is in order to make each OFDM symbol have unique OFDM symbol number in a radio frames.

The Gold sequencer can increase or reduce the initial value of m sequence along with the increase of OFDM symbol number with predetermined interval.For example, allowing sub-district ID is that the sub-district of CELLID1 is along with the OFDM symbol number increases by 1 and initial value is increased predetermined value such as CELLID1 or CELLID1+1.In addition, allowing sub-district ID is that the sub-district of CELLID2 is along with the OFDM symbol number increases by 1 and initial value is increased predetermined value such as CELLID2 or CELLID2+1.But, when the sub-district of minizone ID has difference about twice, might go wrong.For example, if CELLID1=5, CELLID2=11, and predetermined value is respectively CELLID1+1 and CELLID2+1 then number increases along with the OFDM symbol, and initial value increases by 6 and 12 respectively, and there is the difference of twice in this.This situation can be represented with the binary format that a bit takes place to be shifted.This is because 6 be ' 0110 ' in binary format, and 12 is ' 1100 ' in binary format.When bit of displacement, under the situation that adopts the QPSK modulation,, crossover cause their cross correlation to worsen because taking place between the Q axle component of the contrast signal of the I axle component of the reference signal of first sub-district and second sub-district.

Therefore, along with OFDM symbol number and/or subframe numbers increase,, initial value makes that the increment of a sub-district is not the twice of the increment of another sub-district thereby need being set.This can be by making initial value to increase or reduce and easily realize along with OFDM symbol number and/or subframe numbers increase with odd-multiple.For example, make that sub-district ID is that the initial value of the Gold sequencer of n can or reduce to increase or reduces (2n+1) doubly along with the increase of OFDM symbol number.

This can be that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and is depicted as following equation:

[equation 16]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Here, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, r _{L, ns}Be reference signal sequence, and N _RB ^{Max, DL}Be the maximum number of RB, in this case, sequencer can utilize equation to carry out initialization:

[equation 17]

$c_{\mathrm{init}}=2^9\&CenterDot;(l^{\&prime;}+1)\&CenterDot;(2\&CenterDot;N_{\mathrm{ID}}^{\mathrm{cell}}+1)+N_{\mathrm{ID}}^{\mathrm{cell}}$

Wherein, l ' is defined as 8n _s+ l, and be OFDM symbol number in the radio frames.

Simultaneously, the cross-correlation between the pseudo random sequence depends on the result of the binary system addition that produces two employed initial values of pseudo random sequence, and is depicted as following equation:

[equation 18]

$G_1\left(D\right){\&CirclePlus;G}_2\left(D\right)=X\left(D\right)\&CirclePlus;Y_1\left(D\right)\&CirclePlus;X\left(D\right){\&CirclePlus;Y}_2\left(D\right)$

$=Y_1\left(D\right){\&CirclePlus;Y}_2\left(D\right)$

$=I_{2,\mathrm{cell}1}\left(D\right)/g\left(D\right)\&CirclePlus;I_{2,\mathrm{ecll}2}\left(D\right)/g\left(D\right)$

$=(I_{2,\mathrm{cell}1}\left(D\right)\&CirclePlus;I_{2,\mathrm{cell}2}\left(D\right))/g\left(D\right)$

Therefore, if produce pseudo random sequence by number changing initial value according to each OFDM symbol, then when the result of the binary system addition of the initial value of each sub-district along with the variation of OFDM symbol number and when changing, obtained good their cross correlation.This means the initial value c of first sub-district _Init(n ₁, l) and the initial value c of second sub-district _Init(n ₂, l) change along with the variation of OFDM symbol l.Here, n ₁Be the sub-district ID of first sub-district, and n ₂Be the sub-district ID of second sub-district.In addition, consider the QPSK modulation, when

With

When changing, can obtain good their cross correlation according to OFDM symbol l.

Figure 17 shows the setting of the initial value of Gold sequencer.The initial value of the 2nd LFSR of 31 bits is divided into two zones (that is, regional #1 and regional #2).Each zone is made up of 14 bits.Zone #2 is positioned at LSB one side.Can be set to arbitrary value from residue 4 bits that MSB begins.Among zone #1 and the regional #2 each includes the binary sequence of sub-district ID.At regional #1, according to OFDM symbol l with the first cyclic shift m ₁Binary sequence to sub-district ID carries out cyclic shift.At regional #2, according to OFDM symbol l with the second cyclic shift m ₂Binary sequence to sub-district ID carries out cyclic shift.For example, at regional #1, can be with cyclic shift lm ₁Binary sequence to sub-district ID carries out cyclic shift, and at regional #2, can be with cyclic shift lm ₂Binary sequence to sub-district ID carries out cyclic shift.By initial value being divided into two zones and adopting the binary sequence of the sub-district ID of different cyclic shifts, make by being included in each zone

Can change according to OFDM symbol l.

If b ₁The size of representing regional #1, and b ₂The size of representing regional #2, then b ₁=b ₂=14.The size of zone #1 and regional #2 can be set arbitrarily in the scope of initial value.In order to increase the generation cycle of Gold sequence, can be with b ₁And b ₂Be arranged to relatively prime.In addition, can also be with m ₁And b ₁Also be arranged to relatively prime and with m ₂Also be arranged to relatively prime with b2.

This can be that the form of reference signal of the 3GPP LTE system of unit Resources allocation is represented in order to RB, and is depicted as following equation:

[equation 19]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, at the section start of each OFDM symbol

$c_{\mathrm{init}}=2^{14}\&CenterDot;{\mathrm{CS}}_{13}(2N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{1,11}\&CenterDot;l^{\&prime;})+C{S}_{14}(2N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{1,3}\&CenterDot;l^{\&prime;}),$

And

L ' is the OFDM symbol number in the radio frames, CS _b(M a) is cyclic shift function, and

Expression is got and is rounded (floor) function downwards less than the maximum integer of x.

Though it is the downlink reference signal that is used for 3GPP LTE/LTE-A that the sequence that is proposed has been described, the sequence that is proposed also can be used for uplink reference signals.In addition, though at the reference signal of minizone PAPR and their cross correlation have been described, these characteristics can also be used for the reference signal between UE and/or between antenna with being equal to.

The reference signal that is used for the sequence that proposed can be sub-district public reference signal or UE DRS (Dedicated Reference Signal).

Figure 18 illustrates the flow chart that sends the method for reference signal according to an embodiment of the invention.This method can be carried out by transmitter.When sending downlink reference signal, transmitter can be the part of BS, and perhaps when sending uplink reference signals, transmitter can be the part of UE.At step S510, produce reference signal sequence.This reference signal sequence can be defined by following equation:

[equation 20]

$r_{l,n_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A2009800000670030H1.png,A2009800000670033H1.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Here, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, r _{L, ns}Be reference signal sequence, and N _RB ^{Max, DL}It is the maximum number of RB.Pseudo random sequence c (i) can be defined by top equation 7.Here, m sequence x (i) can use by x (0)=1, x (i)=0, and i=1,2 ..., 30 initial values of expressing come initialization, and m sequence (y) can be used according to (2N _ID ^Cell+ 1) initial value of Huo Deing comes initialization, wherein N _ID ^CellBe sub-district ID.The initial value of m sequences y (i) changes along with the variation of OFDM symbol l.Therefore, can be according to l (2N _ID ^Cell+ 1) obtains the initial value of m sequences y (i) in.

In step S520, the part of reference signal sequence or all be mapped at least one RB.A RB can comprise 12 subcarriers.Under the situation of sub-district public reference signal, two modulation symbols of reference sequences can be mapped on two interior subcarriers of a RB.Under the situation of UE DRS (Dedicated Reference Signal), three modulation symbols of reference signal sequence can be mapped on three interior subcarriers of a RB.

At step S530, utilize RB to send reference signal.The reference signal sequence that is proposed provides improved PAPR and their cross correlation.Therefore, can increase the emission effect of transmitter, and receiver can have higher detection performance.

Figure 19 illustrates the block diagram of the transmitter and receiver of the method that has realized transmission and received reference signal.Transmitter 800 comprises data processor 810, reference signal generator 820 and radiating circuit 830.Data processor 810 process information bits send signal to produce.Reference signal generator 820 produces reference signal.Can carry out the generation of the reference signal of Figure 18 by reference signal generator 820.Radiating circuit 830 sends this and sends signal and/or this reference signal.

Receiver 910 comprises data processor 910, channel estimator 920 and receiving circuit 930.Receiving circuit 930 receives reference signal and received signal.Channel estimator 920 utilizes the reference signal that receives to estimate channel.Data processor 910 utilizes estimated channel to handle this received signal.

Although as example the sequence that proposes is used for reference signal in the above-described embodiment, the sequence that is proposed also can be used for various signals.For example, the sequence that is proposed can be used for scrambler, synchronizing signal, lead code, mask etc.Based on the pseudo random sequence c (i) of equation 7, can produce the basic sequence of equation 20.Can use according to (2N ^ID _Cell+ 1) initial value of Huo Deing comes initialization to be used for the m sequences y (i) of pseudo random sequence c (i), wherein N _ID ^CellBe sub-district ID.Can use basic sequence to echo signal or object code.For echo signal or object code are used basic sequence, can be according to the length (or size) of the resource of being distributed or echo signal or object code, the part of use reference signal sequence or all.Send applied sequence.The sequence of this transmission can be received machine as various uses.

The present invention can realize by hardware, software or both combinations.In hardware was realized, the present invention can be by being designed for one of following device of carrying out above-mentioned functions and their combination realizes: application-specific integrated circuit (ASIC) (ASIC), digital signal processor (DSP), programmable logic device (PLD), field programmable gate array (FPGA), processor, controller, microprocessor, other electronic units.In software was realized, the present invention can realize by the module that is used to carry out above-mentioned functions.Software can be stored and be carried out by processor at memory cell.The various means of common general knowledge can be used as memory cell or processor to those skilled in the art.

Although with reference to illustrative embodiments of the present invention, be shown specifically and introduced the present invention, but should be appreciated that those skilled in the art can carry out various modifications to the present invention in form and details under the situation that does not break away from the spirit and scope of the present invention that limited by claims.This illustrative embodiments should be regarded as only for the purpose of describing rather than limiting.Therefore, scope of the present invention is not by specific descriptions of the present invention but is limited by claims, and all differences that fall in this scope all should be interpreted as comprising in the present invention.

Claims (14)

1, a kind of method that sends reference signal in wireless communication system, this method comprises the steps:

The reference signal sequence that generation is defined by following formula,

$r_{{l,n}_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+j\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is OFDM (OFDM) symbol number in the time slot, and N _RB ^{Max, DL}Be the maximum number of Resource Block (RB),

Wherein, pseudo random sequence c (i) is produced by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier;

With the part of described reference signal sequence or all be mapped at least one RB; And

Send the reference signal among described at least one RB.

2, method according to claim 1, wherein, described pseudo random sequence c (i) is defined by following formula,

c(i)＝(x(i+Nc)+y(i+Nc))mod?2

x(i+31)＝(x(i+3)+x(i))mod?2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod?2

Wherein, x (i) and y (i) are that m sequence and Nc are constant.

3, method according to claim 2 wherein, is utilized x (0)=1, x (i)=0, and i=1,2 ..., 30 couples of m sequence x (i) carry out initialization, and utilize described initial value that m sequence (y) is carried out initialization.

4, method according to claim 2, wherein, Nc is the value that is in 1500 to 1800 scopes.

5, method according to claim 1, wherein, described initial value is along with the variation of OFDM symbol number and change.

6, method according to claim 5 wherein, is utilized l (2N _ID ^Cell+ 1) obtains described initial value.

7, method according to claim 1, wherein, described initial value is of a size of 31 bits.

8, method according to claim 1, wherein, a RB comprises 12 subcarriers in frequency domain.

9, method according to claim 8, wherein, two modulation symbols of described reference signal sequence are mapped on two subcarriers of a RB.

10, method according to claim 1, wherein, described reference signal is sub-district public reference signal or subscriber equipment (UE) DRS (Dedicated Reference Signal).

11, a kind of transmitter, this transmitter comprises:

Reference signal generator, it produces reference signal; And

Radiating circuit, it sends described reference signal,

Wherein, described reference signal generator is by producing by the defined reference signal sequence of following formula, and with the part of described reference signal sequence or all be mapped at least one RB, produces described reference signal:

$r_{{l,n}_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+j\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, and N _RB ^Max, DL is the maximum number of RB,

Wherein, pseudo random sequence c (i) is produced by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier.

12, transmitter according to claim 11, wherein, described pseudo random sequence c (i) is defined by following formula,

c(i)＝(x(i+Nc)+y(i+Nc))mod?2

x(i+31)＝(x(i+3)+x(i))mod?2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod?2

Wherein, x (i) and y (i) are that m sequence and Nc are constant.

13, a kind of receiver, this receiver comprises:

Receiving circuit, it receives reference signal and received signal;

Channel estimator, it utilizes described reference signal to estimate channel; And

Data processor, it utilizes described channel to handle described received signal,

Wherein, described reference signal produces based on the reference signal sequence by the following formula definition:

$r_{{l,n}_s}\left(m\right)=\frac{1}{\sqrt{2}}(1-2\&CenterDot;c\left(2m\right))+j\frac{1}{\sqrt{2}}(1-2\&CenterDot;c(2m+1)),m=\mathrm{0,1},...,2N_{\mathrm{RB}}^{\max ,\mathrm{DL}}-1$

Wherein, n _sBe the timeslot number in the radio frames, l is the OFDM symbol number in the time slot, and N _RB ^{Max, DL}Be the maximum number of RB,

Wherein, pseudo random sequence c (i) is produced by the Gold sequencer, and this Gold sequencer is by utilizing (2N _ID ^Cell+ 1) initial value that obtains carries out initialization, wherein N _ID ^CellIt is cell identifier.

14, receiver according to claim 13, wherein, described pseudo random sequence c (i) is defined by following formula,

c(i)＝(x(i+Nc)+y(i+Nc))mod2

x(i+31)＝(x(i+3)+x(i))mod2

y(i+31)＝(y(i+3)+y(i+2)+y(i+1)+y(i))mod2

Wherein, x (i) and y (i) are that m sequence and Nc are constant.

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