CN102739597B - Method for generating ACK/NACK (Acknowledge Character/Non-Acknowledgement) signal - Google Patents

Abstract

The invention provides a method for generating an ACK/NACK (Acknowledge Character/Non-Acknowledgement) signal. The method comprises the following steps of: mapping ACK/NACK information to be transmitted at present into a symbol corresponding to a constellation point, wherein the symbol obtained after mapping the ACK information is -1 and the symbol obtained after mapping the NACK information is 1; shortening a zadoff-chu sequence into a sequence of which the length is N<RB>SC as a spread spectrum base sequence, and the N<RB>SC is an effective sub-carrier number of a sub-band; for each OFDM (Orthogonal Frequency Division Multiplexing) symbol which is occupied by the ACK/NACK information on a physical uplink channel (PUCCH), determining a circulation displacement value of the spread spectrum base sequence corresponding to the OFDM symbol; carrying out circulation displacement to the spread spectrum base sequence according to the circulation displacement value; multiplying each element in the spread spectrum base sequence after the circulation displacement with the symbol after the mapping; and converting the sequence obtained from the multiplication into a time domain signal. The method is applicable for a power grid system.

Description

A kind of generation method of ack/nack signal

Technical field

The present invention relates to wireless communication technology, particularly relate to a kind of generation method of ack/nack signal.

Background technology

In current network design, frequency spectrum is distributed in 230M frequency range discretely, can be divided into the discontinuous subband of 40 25kHz, and the subband of minimum frequency is 223.525MHz, and the subband of most high frequency points is 231.65MHz.Multichannel ofdm system is adopted to carry out the network coverage in electric power pool.Multichannel ofdm system adopts OFDM (OFDM) to be basic fundamental, and each road is the subband carrying effective information.User can take a subband or multiple subband carries out business transmission and reception.

In order to improve reliability and the throughput of system, electric power pool introduces HARQ technology.The receiving terminal of network by Physical Uplink Control Channel (PUCCH) to base station (eNode B) feedback reception signal ACK/NACK information.This ACK/NACK information arrives eNode B through certain time delay, eNode B carries out solution reconciliation process to the ACK/NACK information in PUCCH, and according to ACK/NACK information and descending Resources allocation situation dispatching retransmission data, when NACK is too much time, eNodeB can readjust the modulation coding mode of transmission.

In LTE system, when the basic sequence length of ACK/NACK is less than or equal to two Resource Block (24 subcarriers), have employed a kind of sequence of QPSK modulation system.This sequence is obtained by computer search, and object obtains constant coefficients in a frequency domain, low peak average ratio and good their cross correlation, and can obtain abundant sequence number.In order to realize code division multiplexing, LTE system is carried out block to ack/nack signal and is expanded operation.

Because electric power pool is different from LTE system frequency band distribution, subband bandwidth is different, sub-carrier number (length of ack/nack signal basic sequence) shared by PUCCH channel is different, so directly can not adopt the generation basic sequence of ack/nack signal in LTE system in electric power pool.

In addition, in electric power pool, corresponding to a radio frames of a subband, only have an ack/nack signal, there are not the needs of the code division multiplexing of multi-user.And LTE system relates to the code division multiplexing of multi-user, need process ack/nack signal being carried out to code division multiplexing, process more complicated.

As can be seen here, owing to being different from LTE system to the number of ack/nack signal and characteristic requirements in electric power pool, the method generating ack/nack signal in existing LTE system is not suitable for electric power pool.At present a kind of ack/nack signal generation method being applicable to electric power pool is not yet proposed.

Summary of the invention

In view of this, main purpose of the present invention is a kind of generation method providing ack/nack signal, and the method is applicable to electric power pool.

In order to achieve the above object, the technical scheme that the present invention proposes is:

A generation method for ack/nack signal, the method comprises the following steps:

A, the symbol becoming constellation point corresponding the ACK/NACK information MAP that current needs send, wherein, the symbol that ACK information obtains after mapping is-1, and the symbol that nack message obtains after mapping is 1;

B, to be length by zadoff-chu sequence truncation be sequence, by this length be sequence as spread spectrum basic sequence, described in it is effective sub-carrier number of a subband;

C, described ACK/NACK information is needed on PUCCH to each OFDM symbol of taking, determine that described spread spectrum basic sequence corresponds to the cyclic shift value of this OFDM symbol, according to this cyclic shift value, cyclic shift is carried out to described spread spectrum basic sequence, each element in spread spectrum basic sequence after cyclic shift is multiplied with the symbol obtained after described mapping, and the sequence obtained after being multiplied is converted to time-domain signal.

In sum, the generation method of the ack/nack signal that the present invention proposes, does not need the processing procedure of carrying out code division multiplexing, and step is simple, and complexity is low, matches to the number of ack/nack signal and characteristic requirements with electric power pool.

Accompanying drawing explanation

Fig. 1 is PUCCH channel architecture in electric power pool;

Fig. 2 is the schematic flow sheet of the embodiment of the present invention one

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, the present invention is described in further detail below in conjunction with the accompanying drawings and the specific embodiments.

In a subband of electric power pool, front 4 symbols being numbered the subframe of 2 of a PUCCH channel occupancy radio frames.A subframe comprises 9 symbols, corresponding 10 the effective subcarriers of each symbol.Fig. 1 gives PUCCH channel architecture.Ack/nack signal takies two symbols, and corresponding 1st and the 4th symbol, represent with blank boxes; PUCCH demodulation reference mark corresponding 2nd and the 3rd symbol, represent with striped square.

Core concept of the present invention is: based on the channel architecture of PUCCH in above-mentioned electric power pool, only sends an ack/nack signal and there is not the feature of multiuser multiplexing, generate ack/nack signal for a subframe.

Fig. 2 gives the schematic flow sheet of one embodiment of the invention.As shown in Figure 2, this embodiment realizes at the transmit leg of ACK/NACK information, mainly comprises the following steps:

Step 201, the symbol becoming constellation point corresponding the ACK/NACK information MAP that current needs send, wherein, the symbol that ACK information obtains after mapping is-1, and the symbol that nack message obtains after mapping is 1.

In actual applications, after the ACK/NACK information raw CMOS macro cell ACK/NACK information of transmit leg, by the symbol becoming constellation point corresponding this ACK/NACK information MAP by modulation module, here employing BPSK modulation system is realized this mapping, namely the symbol that ACK information obtains after mapping is-1, and the symbol that nack message obtains after mapping is 1.

Step 202, to be length by zadoff-chu sequence truncation be sequence, by this length be sequence as spread spectrum basic sequence.

Described be effective sub-carrier number of a subband, in electric power pool, be generally 10.

In this step, will be realized by spread spectrum basic sequence generation module.Preferably, following method can be adopted to be length by default zadoff-chu sequence truncation be sequence:

Step 2021 according to calculate the radical sign q of the zadoff-chu sequence that this community uses, for the identification number of community;

Step 2022, according to calculate each element value x of described zadoff-chu sequence _q(m).

Wherein, m is element number, 0≤m≤N _zc-1, N _zcfor the length of described zadoff-chu sequence, N _zcdescribed in closest prime number, such as, when when being 10, be then 11 closest to the prime number of 10, then the length N of now described zadoff-chu sequence _zcbe 11.

Step 2023, according to the described length obtained after determining brachymemma is each element of sequence, wherein k is element number,

Step 203, described ACK/NACK information is needed on PUCCH to each OFDM symbol of taking, determine that described spread spectrum basic sequence corresponds to the cyclic shift value of this OFDM symbol, according to described cyclic shift value, cyclic shift is carried out to described spread spectrum basic sequence, each element in the spread spectrum basic sequence obtained after cyclic shift is multiplied with the symbol obtained after described mapping, and the sequence obtained after being multiplied is converted to time-domain signal.

In actual applications, carry out corresponding cyclic shift by circular shift module, described in resource mapping module and IDFT module are carried out, be converted to the process of time-domain signal.

Concrete, multiple method can be adopted to determine the figure place needing to carry out cyclic shift, as long as realize the object of stochastic generation, such as, the method in existing LTE system can be adopted to realize.Preferably, in order to reduce algorithm complex, can be according to determine the cyclic shift value α (l) that described spread spectrum basic sequence is corresponding in this OFDM symbol, wherein, l is the numbering of described OFDM symbol, c () for length be the Gold pseudo random sequence of 31, its initial value is the identification number of community.

In actual applications, after described cyclic shift value α (l) is determined, can be according to determine each element in the spread spectrum basic sequence after cyclic shift wherein, k is element number, l is the numbering of described OFDM symbol, for described length is the kth element of sequence.

Here, preferably, the sequence obtained after being multiplied can be converted to time-domain signal by impact in order to evade direct current shunting according to the following equation:

$s_l\left(t\right)=\underset{k\&prime;=-N_{\mathrm{sc}}^{\mathrm{RB}}/2}{\overset{N_{\mathrm{sc}}^{\mathrm{RB}}/2-1}{\mathrm{\&Sigma;}}}{x}_{k\&prime;+N_{\mathrm{sc}}^{\mathrm{RB}}/2,l}\&CenterDot;e^{-2\mathrm{\&pi;}(k\&prime;+N_{\mathrm{sc}}^{\mathrm{RB}}/2+{\mathrm{Fshift}}_{\mathrm{subband}})\mathrm{\&Delta;f}(t-N_{\mathrm{CP},l}{T}_s)}$

Wherein, Δ f is subcarrier spacing, Δ f=2kHz in power network;

N _{cP, l}counting of the Cyclic Prefix of described OFDM symbol, l is the numbering of described OFDM symbol, is numbered the N of the OFDM symbol of 0 in power network _{cP, 0}=7, be numbered the N of the OFDM symbol of 3 _{cP, 3}=6;

Fshift _subbandfor preset the frequency shift factor, preferably, in power network OFDM symbol place subband be numbered even number time, Fshift _subband=500/ Δ f, OFDM symbol place subband be numbered odd number time Fshift _subband=-500/ Δ f;

T _s=1/ (N* Δ f), N is that IDFT counts, and power network is for being generally 64;

for of described OFDM symbol the value of individual element;

S _lt (), for described OFDM symbol is at the time-domain signal of time t, the unit of t is second; 0≤t < (N _{cP, l}+ N) × T _s.

As can be seen here, for the ack/nack signal generation aspect in LTE, the processing procedure of carrying out code division multiplexing is not needed in said method, step is simple, complexity is low, and the frame had with electric power pool only sends an ACK/NACK information and do not need the feature of carrying out user multiplexing to adapt.

In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. a generation method for ack/nack signal, it is characterized in that, the method comprises the following steps:

A, the symbol becoming constellation point corresponding the ACK/NACK information MAP that current needs send, wherein, the symbol that ACK information obtains after mapping is-1, and the symbol that nack message obtains after mapping is 1;

B, to be length by zadoff-chu sequence truncation be sequence, by this length be sequence as spread spectrum basic sequence, described in it is effective sub-carrier number of a subband;

C, for each orthogonal frequency division multiplex OFDM symbol described ACK/NACK information physically row control channel PUCCH needing take, determine that described spread spectrum basic sequence corresponds to the cyclic shift value of this OFDM symbol, according to this cyclic shift value, cyclic shift is carried out to described spread spectrum basic sequence, each element in spread spectrum basic sequence after cyclic shift is multiplied with the symbol obtained after described mapping, and according to $s_l\left(t\right)=\underset{k^{\&prime;}=-N_{\mathrm{sc}}^{\mathrm{RB}}/2}{\overset{N_{\mathrm{sc}}^{\mathrm{RB}}/2-1}{\mathrm{\&Sigma;}}}{x}_{k^{\&prime;}+N_{\mathrm{sc}}^{\mathrm{RB}}/2,l}\&CenterDot;e^{j2\mathrm{\&pi;}(k^{\&prime;}+N_{\mathrm{sc}}^{\mathrm{RB}}/2+F{\mathrm{shift}}_{\mathrm{subband}})\mathrm{\&Delta;f}(t-N_{\mathrm{CP},l}{T}_s)}$ The sequence obtained after being multiplied is converted to time-domain signal; Wherein, Δ f is subcarrier spacing, N _{cP, l}counting of the Cyclic Prefix of described OFDM symbol, l is the numbering of described OFDM symbol; Fshift _subbandfor the frequency shift factor preset, T _s=1/ (N* Δ f), N is that IDFT counts, for of described OFDM symbol the value of individual element; 0≤t < (N _{cP, l}+ N) × T _s, s _lt () is for described OFDM symbol is at the time-domain signal of time t.

2. method according to claim 1, is characterized in that, being length by default zadoff-chu sequence truncation in step b is sequence be:

According to calculate the radical sign q of the zadoff-chu sequence that this community uses, for the identification number of community;

According to calculate each element value x of described zadoff-chu sequence _qm (), wherein, m is element number, 0≤m≤N _zc-1, N _zcfor the length of described zadoff-chu sequence, N _zcdescribed in closest prime number;

According to the described length obtained after determining brachymemma is each element of sequence, wherein k is element number, $0\&le;k\&le;N_{\mathrm{sc}}^{\mathrm{RB}}-1.$

3. method according to claim 1, is characterized in that, in described step c according to cyclic shift is carried out to described spread spectrum basic sequence, obtains each element r in the spread spectrum basic sequence after cyclic shift _q ^{α (l)}(k), wherein, k is element number, l is the numbering of described OFDM symbol, and α (l) is described cyclic shift value, for described length is the kth element of sequence.