CN106713212A - Combined receiving method of multi-carrier system accumulatively distributed based on average bit error ratio - Google Patents

Abstract

The invention discloses a combined receiving method of a multi-carrier system accumulatively distributed based on an average bit error ratio. The method comprises: step 1, exactly describing basic expression of a receiving signal under Gaussian disturbance; step 2, deducing and computing a theoretical bit error rate of a channel, wherein gain of the channel is expressed by a local average bit error ratio; step 3, simulating conditions of the average bit error ratio by utilizing a Monte Carlo numerical simulation method, and obtaining a current average bit error ratio; and step 4, judging whether the gain of the channel can be up to standard under given conditions according to the obtained current average bit error ratio in step 3.

Description

A kind of multicarrier system joint method of reseptance based on average error rate cumulative distribution

Technical field

Combine method of reseptance the present invention relates to a kind of multicarrier system based on average error rate cumulative distribution, belong to electronics Communication technical field.

Background technology

Multicarrier system is presented sparse characteristic due to its channel, therefore it possesses frequency of the stronger confrontation in the case of multichannel Rate selectivity, is all the time the focus of research, and be considered as new generation broadband while having band efficiency higher One of alternative of wireless access.Along with the application in frequency domain to orthogonal intersection, the data of user are by multicarrier The spread spectrum that the emitter of system is carried out.Preferable bit error rate (BER) is obtained in severe fading environment can be by frequency Domain equalizing technology is achieved.Certainly, can be applied frequently using in multicarrier system with Direct Digital sequential system identical Divide multiplexing, it is also possible to achieve the goal by limiting bandwidth.For mobile subscriber, caused by shade and distance decline Received signal power reduction can be compensated by position diversity receiving method.These methods can improve downlink Transmission performance.By Computer Simulation, newest site diversity method shows the frequency by the way that least mean-square error is used in combination Domain equilibrium (MMSE-FDE) and reception deversity scheme can be greatly enhanced the capacity of downlink.However, these are by calculating The conclusion that obtains of machine emulation how to be verified in theory there are still Theoretical Framework it is unintelligible, mathematical definition is disagreed etc. very Big problem, hence sets up a whole set of complete theoretical system to assess the descending chain performance set up by site diversity method just It is particularly important.

The content of the invention

To achieve these goals, the invention provides a kind of multicarrier system connection based on average error rate cumulative distribution Splice grafting receiving method.

The technical scheme that the present invention takes is as follows：

A kind of multicarrier system joint method of reseptance based on average error rate cumulative distribution, comprises the following steps：

The first step：Accurate description receives the basal expression of signal under Gauss interference；

In base station in i microcellulor j user u, its parallel data sequence N_C/ SF can be from modulated signal sequence { d_u(j)(n)； N=0~N_C/ SF-1 } in obtained by serioparallel exchange (S/P).The output of S/P conversions is multiplied by just by calculating spreading factor SF Hand over spreading code { C_u(j)(k)；K=0~SF-1 } obtain；Generally, the interlaced code { C of base station i_PN(i)(k)；K=0~N_c- 1 } be by Do what multiplication was used as the user's spread-spectrum signal for combining each subcarrier；The effect of different interleaving code receives those Composite signal changes into class white noise acoustic property, it is possible to extract the positional information of different microcellulors.Define kth subcarriers Composite received signal be：

Based on above-mentioned equation, wherein P_iIt is transimission power, channel (user) number of activity in the i of base station is U+ δ u_i, in position The extra reserved number of channel is δ u in diversity computing_i；Consider | d_u(i)(n) |=| c_u(i)(k) |=| c_PN(i)(k) |=1, then, Orthogonal spectrum expansion interlaced code can be expressed as：Orthogonal spectrum expansion interlaced code can be expressed as：

However, due to the presence of multi-access inference (MAI, multiple access interference), multipath fading letter It is no desired orthogonality in road；

Multi-access inference MAI is defined as follows：

Wherein,By formula (1), (2), (3) understand that variance is：

In addition, between honeycomb mutual interference ICI (inter-cellular interference) be because interlaced code is non-orthogonal Produced between honeycomb, it may be defined as：

Second step：Deduce and calculate the theoretical bit error rate of channel；The gain of channel is characterized by local average error rate, Its value is obtained by statistical average and numerical simulation, can be expressed as：

3rd step：The condition of average error rate is simulated using Monte Carlo numerical value emulation method and obtains current Average error rate；

4th step：Average error rate according to the 3rd step judges whether channel gain can reach under given conditions Standard.

Beneficial effect of the present invention：A kind of brand-new method based on MMSE and space diversity is proposed to lift variable frequency The performance of selective channel, is found by simulation result, and theoretical and Computer Simulation given herein is mutually confirmed, and can be to grind The performance for studying carefully radio honeycomb multi-access systems downlink provides a kind of new thinking

Brief description of the drawings

Fig. 1 is composite received signal structure diagram.

Fig. 2 downlinks multicarrier cellular system transmitter/receiver.

Influences of Fig. 3 shadow fadings β to downlink capacity.

Fig. 4 (a) is channel gain emulation when only considering MAI.

Fig. 4 (b) is channel gain emulation when only considering ICI.

Specific embodiment

The present invention will be further described below in conjunction with the accompanying drawings.

System model

Multicarrier system includes the signals such as orthogonal intersection, interlaced code and white Gaussian noise, and wherein orthogonal intersection is used To confirm user, and interlaced code can be used to separate the position of microcellulor.As it was previously stated, frequency selective fading channels are difficult Perfect orthogonality is obtained in user, as shown in figure 1, the gain of subcarrier is no longer constant, this can bring about multi-access inference (multiple access interference, MAI).

Assuming that the number of subcarriers of multicarrier system is N_C, spreading factor is SF, and Fig. 2 gives and uses least mean-square error Frequency domain equalization (MMSE-FDE) and receive deversity scheme joint receive system block diagram, including transmitting and receive 2 parts.

Transmission signal mathematical expression

Consider the user u, its parallel data sequence N of microcellulor j in i in base station_C/ SF can be from modulated signal sequence { d_u(j) (n)；N=0~N_C/ SF-1 } in obtained by serioparallel exchange (S/P).The output of S/P conversions is multiplied by calculating spreading factor SF With orthogonal intersection { C_u(j)(k)；K=0~SF-1 } obtain.Generally, the interlaced code { C of base station i_PN(i)(k)；K=0~N_c-1} It is used as doing what multiplication was used with reference to user's spread-spectrum signal of each subcarrier.The effect of different interleaving code is to receive those To composite signal change into class white noise acoustic property, it is possible to extract the positional information of different microcellulors.Define kth way The composite received signal of carrier wave is：

Based on above-mentioned equation, wherein P_iIt is transimission power, channel (user) number of activity in the i of base station is U+ δ u_i, in position The extra reserved number of channel is δ u in diversity computing_i.Consider | d_u(i)(n) |=| c_u(i)(k) |=| c_PN(i)(k) |=1, that

, orthogonal spectrum expansion interlaced code can be expressed as：Orthogonal spectrum expansion interlaced code can be expressed as：

However, due to the presence of multi-access inference (MAI, multiple access interference), multipath fading letter It is no desired orthogonality in road.

Multi-access inference MAI is defined as follows：

Wherein,Understand that variance is by formula (1,2,3)：

In addition, between honeycomb mutual interference ICI (inter-cellular interference) be because interlaced code is non-orthogonal Produced between honeycomb, it may be defined as：

The gain of channel is characterized by local average error rate (BER), and its value is obtained by statistical average and numerical simulation Arrive, can be expressed as：

From figure 3, it can be seen that the increase of shadow fading β has little to no effect for downlink capacity.But shade declines The increase of β of falling can cause jamming power to increase so that the probability that interference occurs also becomes big, therefore downlink capacity Reduce.By after site diversity algorithm, receive the power of signal and have and be remarkably reinforced, illustrate the minor variations of shadow fading β Can be returned by hybrid diversity algorithm compensation, the conclusion of theory analysis is consistent with the result of Computer Simulation.

Find out that interference component is multiple Gauss stochastic variable by Signal to Interference plus Noise Ratio and the bit error rate.Fig. 4 (a) (b) sets forth letter There is the probability density function (PDF, probability density functions) during MAI and ICI in road.It is assumed that each It is normalized power-delay, P that cellular number of users U=27, γ=0dB are represented in channel_th=4.5dB, the height of zero-mean This distribution meets the PDF requirements of MAI, while meeting the approximation of theoretical calculation.

If be can see in Fig. 4 (a) in the case of only considering MAI, by the joint method of reseptance of this paper, systematic function Larger improvement is obtained；If be can see in Fig. 4 (b) in the case of only considering ICI, by the joint method of reseptance of this paper, Systematic function has also obtained larger improvement.It is of course possible to find out, if channel by MAI in the case of only being influenceed, signal Fading severity than channel be subject to ICI when it is more severe, that is to say, that the joint method of reseptance being mentioned herein for treatment channel in ICI it is more effective.

Claims (1)

1. a kind of multicarrier system based on average error rate cumulative distribution combines method of reseptance, it is characterised in that：Including as follows Step：

The first step：Accurate description receives the basal expression of signal under Gauss interference；

In base station in i microcellulor j user u, its parallel data sequence N_C/ SF can be from modulated signal sequence { d_u(j)(n)；N=0 ~N_C/ SF-1 } in obtained by serioparallel exchange (S/P).The output of S/P conversions is to be multiplied by orthogonal expansion by calculating spreading factor SF Frequency code { C_u(j)(k)；K=0~SF-1 } obtain；Generally, the interlaced code { C of base station i_PN(i)(k)；K=0~N_c- 1 } it is used as Do what multiplication was used with reference to user's spread-spectrum signal of each subcarrier；The effect of different interleaving code is the synthesis for receiving those Signal changes into class white noise acoustic property, it is possible to extract the positional information of different microcellulors.Define answering for kth subcarriers Splice grafting is collected mail：

Based on above-mentioned equation, wherein P_iIt is transimission power, channel (user) number of activity in the i of base station is U+ δ u_i, in site diversity The extra reserved number of channel is δ u in computing_i；Consider | d_u(i)(n) |=| c_u(i)(k) |=| c_PN(i)(k) |=1, then, it is orthogonal Spread spectrum interlaced code can be expressed as：Orthogonal spectrum expansion interlaced code can be expressed as：

$\left\{\begin{array}{c}\frac{1}{SF}\underset{k=0}{\overset{SF-1}{\Σ}}{c}_{u\left(i\right)}\left(k\right)c_{u^{\′}\left(i\right)}^{*}\left(k\right)=\mathrm{\δ}(u-u^{\′})\\ E\[c_{PN\left(i\right)}\left(k\right)c_{PN\left(i\right)}\left(k^{\′}\right)\]=\mathrm{\δ}\left(k-k^{\′}\right)\end{array}\right.,---\left(2\right)$

However, being no desired orthogonality due to the presence of multi-access inference, in multidiameter fading channel；

Multi-access inference MAI is defined as follows：

${\mathrm{\μ}}_{MAI}\left(n\right)=\frac{1}{SF}\underset{k=nSF}{\overset{\left(n+1\right)SF-1}{\mathrm{\Σ}}}\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}\underset{b=0}{\overset{D-1}{\mathrm{\Σ}}}\underset{u\left(b\right)\≠u\left(j\right)}{\overset{U+{\mathrm{\δu}}_b-1}{\underset{u\left(b\right)=0}{\mathrm{\Σ}}}}{\mathrm{\ϵ}}_b\sqrt{\frac{2S_{b\_u\left(j\right)}}{SF}}{\tilde{H}}_{b\_u\left(j\right)}\left(k\right)c_{u\left(b\right)}\left(k\mathrm{mod}SF\right)c_{u\left(j\right)}^{*}\left(k\mathrm{mod}SF\right)d_{u\left(b\right)}\left(n\right),---\left(3\right)$

Wherein,By formula (1), (2), (3) understand that variance is：

$2{\mathrm{\σ}}_{\mathrm{\μ}}^2\left(n\right)=\frac{2}{SF}\frac{N_o}{N_c{T}_c}\left[\begin{array}{c}\frac{1}{SF}\underset{k=nSF}{\overset{\left(n+1\right)SF-1}{\mathrm{\Σ}}}\underset{b=0}{\overset{D-1}{\mathrm{\Σ}}}\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}|w_{b\_u\left(j\right)}^{\left(m\right)}\left(k\right){|}^2\\ +\frac{1}{SF}\frac{E_s}{N_o}\underset{b=0}{\overset{D-1}{\mathrm{\Σ}}}{r}_{b\_u\left(j\right)}^{-\mathrm{\α}}{10}^{-\mathrm{\β}\left(b\right)/10}\left(U+{\mathrm{\δu}}_b-1\right)\left\{\frac{1}{SF}\underset{k=nSF}{\overset{\left(n+1\right)SF-1}{\mathrm{\Σ}}}|{\hat{H}}_{b\_u\left(j\right)}\left(k\right){|}^2-|\frac{1}{SF}\underset{k=nSF}{\overset{\left(n+1\right)SF-1}{\mathrm{\Σ}}}{\hat{H}}_{b\_u\left(j\right)}\left(k\right){|}^2\right\}\\ +\frac{1}{SF}\frac{E_s}{N_o}\underset{b=0}{\overset{D-1}{\mathrm{\Σ}}}\underset{i\≠b}{\overset{6}{\underset{i=0}{\mathrm{\Σ}}}}{r}_{i\_u\left(j\right)}^{-\mathrm{\α}}\·{10}^{-\mathrm{\β}\left(i\right)/10}\·\left(U+{\mathrm{\δu}}_i\right)\frac{1}{SF}\underset{k=nSF}{\overset{\left(n+1\right)SF-1}{\mathrm{\Σ}}}\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}|w_{b\_u\left(j\right)}^{\left(m\right)}\left(k\right)H_{i\_u\left(j\right)}^{\left(m\right)}\left(k\right){|}^2\end{array}\right],$

In addition, mutual interference is produced between honeycomb because interlaced code is non-orthogonal between honeycomb, it may be defined as：

$2{\mathrm{\σ}}_{ICI}^2\left(n\right)=\frac{2}{{\mathrm{SF}}^2}\underset{b=0}{\overset{D-1}{\Σ}}\underset{i\≠b}{\overset{\mathrm{\∞}}{\underset{i=0}{\mathrm{\Σ}}}}\frac{S_{i\_u\left(j\right)}}{SF}(U+{\mathrm{\δu}}_i)\frac{1}{SF}\underset{k=nSF}{\overset{(n+1)SF-1}{\Σ}}\underset{m=0}{\overset{M-1}{\Σ}}|w_{b\_u\left(j\right)}^{\left(m\right)}\left(k\right)H_{i\_u\left(j\right)}^{\left(m\right)}\left(k\right){|}^2;---\left(4\right)$

Second step：Deduce and calculate the theoretical bit error rate of channel；The gain of channel is characterized by local average error rate, its value Obtained by statistical average and numerical simulation, can be expressed as：

$P_e\left(\frac{E_b}{N_0}\right)={\∫}_0^{\mathrm{\∞}}...{\∫}_0^{\mathrm{\∞}}{P}_e\left(\mathrm{\γ}\right(E_s/N_0\left|\right\{H_{i\_u\left(j\right)}^{\left(m\right)}\left(k\right)\}\left)\right)p\left(\right\{H_{i\_u\left(j\right)}^{\left(m\right)}\left(k\right)\left\}\right)\underset{m,k,i}{\mathrm{\Π}}{\mathrm{dH}}_{i\_u\left(j\right)}^{\left(m\right)}\left(k\right);---\left(5\right)$

3rd step：It is simulated to the condition of average error rate and obtains current flat using Monte Carlo numerical value emulation method The equal bit error rate；

4th step：Average error rate according to the 3rd step judges whether channel gain can reach mark under given conditions It is accurate.