CN105049099A - Multi-antenna self-adaptive scheduling method for LTE multi-antenna system - Google Patents

Abstract

The invention discloses a multi-antenna self-adaptive scheduling method for an LTE multi-antenna system. The method is performed as follows. A receiving terminal feeds back the signal-to-noise ratio of each channel to a sending terminal. The sending terminal, based on the ratios of signal to noise, calculates the equivalent information quality information under three antenna modes respectively. Following that, the channel capacities under three antenna modes are calculated with a decision coefficient in its wake. If the decision coefficient is greater than or equal to the preset threshold value, then a single antenna mode is adopted. Otherwise, further deciding if the channel capacity in a transmission diversity mode is greater than or equal to the channel capacity in a spatial multiplexing mode; if it is proved to be greater than or equal, then the transmission diversity mode is adopted. If proved not to be greater or equal, then the spatial multiplexing transmission mode is adopted. According to the embodiments of the invention, the signal-to-noise ratio of channel is adopted so as to realize adaptive arrangement of the antenna modes at a sending terminal. In this manner, the antenna modes are capable of automatically adapting to current communication channel condition, therefore, increasing the throughput rate of a system.

Description

The multi-antenna adaptive dispatching method of LTE multiaerial system

Technical field

The invention belongs to LTE communication technical field, more specifically say, relate to a kind of multi-antenna adaptive dispatching method of LTE multiaerial system.

Background technology

In order to tackle the challenge of broadband access technology, simultaneously in order to meet the demand of new business, International Organization for standardization 3GPP (3rdGenerationPartnershipProject) will start universal mobile telecommunications system (UniversalMobileTelecommunicationSystem in the end of the year 2004, UMTS) Long Term Evolution (LongTermEvolution, LTE) project.The object of this project is exactly the mobile communication system of research and development High Data Rate, high channel capacity, low delay and low cost.LTE system have employed with OFDM (OrthogonalFrequencyDivisionMultiple, and multiple-input and multiple-output (MultipleInputMultipleOutput OFDM), MIMO) be the technology of core, also improve the performance of system further with the use of adaptive coding and modulating (AdaptiveModulationandCoding, AMC) technology simultaneously.

MIMO technology is exactly all adopt many antennas at the transmitting-receiving two-end of wireless transmission, compared with traditional single antenna transmissions, multiple parallel spatial sub-channel can be formed between many antennas of transmitting terminal and many antennas of receiving terminal, the transmission information independently and these subchannels can walk abreast, such one side greatly can improve message transmission rate, thus meets two-forty and jumbo requirement; The anti-fading of system and noise resisting ability can be improved well again on the other hand.Therefore, MIMO technology is also considered to future mobile communications and PCS Personal Communications System realizes high speed data transfers, improves the important channel of transmission quality.

AMC technology is exactly the change according to channel condition, dynamically selects suitable modulation and coded system (ModulationandCodingScheme, MCS).This technology has been widely used in existing wireless communication system.Its basic thought is exactly the channel condition information utilizing receiving terminal to feed back to measure at transmitting terminal, the parameters such as modulation and coded system MCS, data rate and transmitted power are obtained by certain process, then data transmission is carried out by these parameters, to guarantee that systematic function reaches optimum under difficult channel conditions.

The general principle of Adaptive Modulation and Coding is exactly according to current channel condition information CSI, be presented as Signal to Interference plus Noise Ratio SINR or the signal to noise ratio snr of now transmission channel, dynamically regulate the coded modulation scheme of transmission channel at receiving terminal, thus make radio channel resource maximum using.But the simple Adaptive Modulation and Coding that uses can not really make system gain and maximizes system performance, and also need to adopt multiple antenna scheduling to coordinate.Fig. 1 is Adaptive Modulation and Coding AMC model framework chart.As shown in Figure 1, except adopting Adaptive Modulation and Coding, can also multiple antenna scheduling be adopted, the antenna mode of transmitting terminal is controlled.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of multi-antenna adaptive dispatching method of LTE multiaerial system is provided, make antenna mode can automatically adapt to present channel environment, improve system throughput.

For achieving the above object, the multi-antenna adaptive dispatching method of LTE multiaerial system of the present invention, comprises the following steps:

S1: receiving terminal feeds back the signal to noise ratio of each channel to transmitting terminal wherein i represents the sequence number of channel, and span is i=1,2 ..., T, T are the number of feedback channel;

S2: receiving terminal is according to signal to noise ratio calculate the equivalent information quality information SINR under three kinds of antenna modes respectively _sISO, SINR _tDand SINR _sM, wherein subscript SISO represents single antenna pattern, and subscript TD represents transmitting diversity pattern, subscript SM representation space multiplexer mode; Computing formula is respectively:

${\mathrm{SINR}}_{SISO}=\frac{1}{T}\underset{i=1}{\overset{T}{\Σ}}{\mathrm{SINR}}_R^i$

${\mathrm{SINR}}_{TD}=\frac{M}{T}\underset{i=1}{\overset{T}{\Σ}}{\mathrm{SINR}}_R^i$

${\mathrm{SINR}}_{SM}=2^{\frac{1}{T}\underset{i=1}{\overset{T}{\Σ}}{\log }_2{(1+{\mathrm{SINR}}_R^i)}^N}-1$

Wherein, M represents transmitting terminal antenna number, and N represents receiving terminal antenna number;

S3: the channel capacity C calculating three kinds of antenna modes respectively _sISO, C _tDand C _sM, computing formula is:

C _SISO＝log ₂(1+SINR _SISO)

C _TD＝log ₂(1+SINR _TD)

C _SM＝M×log ₂(1+SINR _SM)

S4: calculate judgement factor alpha, computing formula is:

$\mathrm{\α}=\frac{C_{SISO}}{max(C_{TD},C_{SM})}$

S5: if α>=α _th, adopt single antenna pattern; If not, then judge whether C further _tD>=C _sM, if so, then adopt transmitting diversity pattern, otherwise adopt space multiplexing mode.

The multi-antenna adaptive dispatching method of LTE multiaerial system of the present invention, receiving terminal feeds back the signal to noise ratio of each channel to transmitting terminal, transmitting terminal calculates the equivalent information quality information under three kinds of antenna modes respectively according to signal to noise ratio, then the channel capacity of three kinds of antenna modes is calculated, calculate judgement coefficient again, if judgement factor is more than or equal to predetermined threshold value, then adopt single antenna pattern; Otherwise judge whether the channel capacity of transmitting diversity pattern is more than or equal to the channel capacity of space multiplexing mode further, if it is adopt transmitting diversity pattern, otherwise adopt space multiplexing mode.The present invention arranges the antenna mode of transmitting terminal adaptively by channel SNRs, makes antenna mode can automatically adapt to present channel environment, and then improves system throughput.

Accompanying drawing explanation

Fig. 1 is Adaptive Modulation and Coding AMC model framework chart;

Fig. 2 is the flow chart of the multi-antenna adaptive dispatching method of LTE multiaerial system of the present invention;

Fig. 3 is the throughput of system curve chart under different judgement coefficient thresholding;

The throughput graph of PedB channel under different antennae pattern when being 2 × 2 that Fig. 4 is number of antennas;

The throughput graph of PedB channel under different antennae pattern when being 4 × 4 that Fig. 5 is number of antennas;

The throughput graph of VehA channel under different antennae pattern when being 2 × 2 that Fig. 6 is number of antennas;

The throughput graph of VehA channel under different antennae pattern when being 4 × 4 that Fig. 7 is number of antennas;

The throughput graph of HI channel under different antennae pattern when being 2 × 2 that Fig. 8 is number of antennas;

The throughput graph of HI channel under different antennae pattern when being 4 × 4 that Fig. 9 is number of antennas.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, so that those skilled in the art understands the present invention better.Requiring particular attention is that, in the following description, when perhaps the detailed description of known function and design can desalinate main contents of the present invention, these are described in and will be left in the basket here.

Embodiment

Fig. 2 is the flow chart of the multi-antenna adaptive dispatching method of LTE multiaerial system of the present invention.Shown in each Fig. 2, the multi-antenna adaptive dispatching method of LTE multiaerial system of the present invention comprises the following steps:

S201: receiving terminal feedback channel signal to noise ratio:

Receiving terminal feeds back the signal to noise ratio of each channel to transmitting terminal wherein i represents the sequence number of channel, and span is i=1,2 ..., T, T are the number of feedback channel, i.e. the receive channel number of receiving terminal.

For the ease of calculating, adopt snr computation formula ideally in the present embodiment, the impact become when namely not considering receiving terminal channel estimation errors and channel, computing formula is:

${\mathrm{SINR}}_R^i=\frac{\mathrm{\β}\·P_{SRS}\·\underset{j=1}{\overset{Q}{\Σ}}{p}_c^j}{S_i+N_{0}B}---\left(1\right)$

Wherein, P _sRSfor the received power at node place district pilots measuring-signal (SoundReferenceSignal, SRS); for the channel power of a jth subcarrier is composed, Q is transmission subcarrier number, is determined by system bandwidth B; β is channel fading coefficient, and different channel values is different; N ₀for the power spectral density of interchannel noise; S _irepresent interference power, namely all user's pilot signal reception power sums in neighbor cell, are expressed as wherein refer to the pilot power value in a kth neighbor cell, the span of k is k=1,2 ..., K, K refer to the pilot signal quantity in neighbor cell.When only considering the unique user of a community, interference power S _ivalue can ignore.

S202: calculate equivalent channel quality information:

Receiving terminal is according to signal to noise ratio calculate the equivalent channel quality information SINR under three kinds of antenna modes respectively _sISO, SINR _tDand SINR _sM, computing formula is respectively:

${\mathrm{SINR}}_{SISO}=\frac{1}{T}\underset{i=1}{\overset{T}{\Σ}}{\mathrm{SINR}}_R^i---\left(2\right)$

${\mathrm{SINR}}_{TD}=\frac{M}{T}\underset{i=1}{\overset{T}{\Σ}}{\mathrm{SINR}}_R^i---\left(3\right)$

${\mathrm{SINR}}_{SM}=2^{\frac{1}{T}\underset{i=1}{\overset{T}{\Σ}}{\log }_2{(1+{\mathrm{SINR}}_R^i)}^N}-1---\left(4\right)$

Wherein, M represents transmitting terminal antenna number, and N represents receiving terminal antenna number; Subscript SISO represents single antenna pattern, and subscript TD represents transmitting diversity pattern, subscript SM representation space multiplexer mode.

S203: calculate channel capacity:

According to Shannon's theorems, the channel capacity C of three kinds of antenna modes _sISO, C _tDand C _sMbe respectively:

C _SISO＝log ₂(1+SINR _SISO)(5)

C _TD＝log ₂(1+SINR _TD)(6)

C _SM＝M×log ₂(1+SINR _SM)(7)

S204: calculate judgement factor alpha:

As can be seen from formula (5), (6), (7), work as M=N=1, under three kinds of antenna modes, there is identical equivalent channel quality information and channel capacity, then have SINR _sISO=SINR _tD=SINR _sM, C _sISO=C _tD=C _sM; Work as M, the equivalent channel quality information of N > 1, multiplexer mode SM and diversity mode TD and channel capacity are all large than single antenna Mode S ISO.Based on above analysis, invention introduces judgement factor alpha, its expression formula is:

$\mathrm{\α}=\frac{C_{SISO}}{max(C_{TD},C_{SM})}---\left(8\right)$

The span of obvious judgement factor alpha is 0 < α≤1.Judgement factor alpha can be used to the relative size of measurement three kinds of antenna mode lower channel capacity.

S205: judge whether α>=α _th, α _threpresent the decision threshold preset, arrange according to actual conditions, through experiment statistics, α _thgeneral span is 0.85≤α _th< 1.If so, enter step S206, otherwise enter step S207.

S206: arranging antenna mode is single antenna pattern.This is because as α>=α _ththree kinds of lower channel capacity value that can reach of antenna mode are described closely, also just illustrating adopts single antenna mode can obtain the systematic function similar to multiple antennas mode, but due to single antenna more easy and be easy to realize, so by the compromise of performance and complexity, select the transmission of the antenna mode of single-input single-output more applicable.

S207: judge whether C _tD>=C _sM, if so, illustrate compared to space multiplexing mode, adopt diversity mode can obtain better systematic function, so select diversity mode more suitable, enter step S208, otherwise adopt space multiplexing mode can obtain better systematic function, enter step S209.

As antenna α < α _thtime, illustrate and adopt multiple antennas can obtain better channel capacity, so select from transmit diversity TD and spatial reuse SM two kinds of patterns further with regard to needs, the present invention directly selects according to the size of channel capacity.

S208: arranging antenna mode is diversity mode.

S209: arranging antenna mode is space multiplexing mode.

In actual applications, the scheduling result of antenna mode can be represented with code form, facilitate multi-antenna module identification, the corresponding code such as arranging single-input single-output SISO pattern is 0, the corresponding code of transmit diversity TD pattern is 1, and the corresponding code of spatial reuse SM pattern is 2.

In order to technique effect of the present invention is described, an instantiation is adopted to carry out simulating, verifying to the present invention.The antenna mode adopted in this emulation mainly comprises single antenna SISO pattern, transmitting diversity TD pattern (2 × 2,4 × 4) and spatial reuse SM pattern (2 × 2,4 × 4).

Fig. 3 is the throughput of system curve chart under different judgement coefficient thresholding.As shown in Figure 3, three kinds of channels are illustrated: the throughput of PedB, VehA and HI.Can find out, single, multiple antennas decision threshold α _thunder different value, the throughput of Adaptable System is distinguished to some extent, works as α _thvalue when 0.9 and 0.95, throughput that system obtains can reach maximum.Therefore, judging threshold α is chosen in the present embodiment _th=0.9, namely when judgement factor alpha>=0.9, choose SISO pattern; As α < 0.9, then choose TD or SM pattern.Provide the emulation comparison diagram of the throughput of system under different antennae pattern below.

The throughput graph of PedB channel under different antennae pattern when being 2 × 2 that Fig. 4 is number of antennas.The throughput graph of PedB channel under different antennae pattern when being 4 × 4 that Fig. 5 is number of antennas.As shown in Figure 4 and Figure 5, general at channel condition, when signal to noise ratio is lower, the throughput value that system can reach under SISO, transmitting diversity TD and this Three models of spatial reuse SM is very limited, and numerical value is also very close.By comparison, the present invention has clear superiority, and system can obtain higher throughput under multi-antenna adaptive scheduling method.Under identical channel circumstance, along with the increase of signal to noise ratio snr, the throughput under various antenna mode increases all to some extent, and multi-antenna adaptive scheduling method of the present invention still has advantage.When channel condition is relatively good, no matter number of antennas is 2 × 2 or 4 × 4, the throughput value that SISO pattern and TD pattern, SM pattern and the present invention can obtain closely, and can observe after signal to noise ratio snr reaches 5dB, the present invention selects spatial reuse SM pattern as multi-antenna transmission modes substantially.

The throughput graph of VehA channel under different antennae pattern when being 2 × 2 that Fig. 6 is number of antennas.The throughput graph of VehA channel under different antennae pattern when being 4 × 4 that Fig. 7 is number of antennas.The throughput graph of HI channel under different antennae pattern when being 2 × 2 that Fig. 8 is number of antennas.The throughput graph of HI channel under different antennae pattern when being 4 × 4 that Fig. 9 is number of antennas.As shown in Figures 6 to 9, although compared to PedB channel, VehA channel and HI channel more severe, and throughput value declines all to some extent under often kind of pattern, but as a complete unit, compared with, multi-antenna mode single with fixing, system still has more outstanding performance under multi-antenna adaptive scheduling method of the present invention.

As can be seen from above simulation results, no matter in which kind of simulated environment and which kind of channel condition, be compared to other three kinds fixing antenna modes, multi-antenna adaptive scheduling method of the present invention all has good throughput performance, and all shows stable performance advantage.Can prove thus, the multi-antenna adaptive dispatching method that the present invention proposes significantly can improve the performance of LTE communication system.

Although be described the illustrative embodiment of the present invention above; so that those skilled in the art understand the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various change to limit and in the spirit and scope of the present invention determined, these changes are apparent, and all innovation and creation utilizing the present invention to conceive are all at the row of protection in appended claim.

Claims (3)

1. a multi-antenna adaptive dispatching method for LTE multiaerial system, is characterized in that, comprise the following steps:

S1: receiving terminal feeds back the signal to noise ratio of each channel to transmitting terminal wherein i represents the sequence number of channel, and span is i=1,2 ..., T, T are the number of feedback channel;

S2: receiving terminal is according to signal to noise ratio calculate the equivalent information quality information SINR under three kinds of antenna modes respectively _sISO, SINR _tDand SINR _sM, computing formula is respectively:

${\mathrm{SINR}}_{SISO}=\frac{1}{T}\underset{i=1}{\overset{T}{\&Sigma;}}{\mathrm{SINR}}_R^i$

${\mathrm{SINR}}_{TD}=\frac{M}{T}\underset{i=1}{\overset{T}{\&Sigma;}}{\mathrm{SINR}}_R^i$

${\mathrm{SINR}}_{SM}=2^{\frac{1}{T}\underset{i=1}{\overset{T}{\&Sigma;}}{\log }_2{(1+{\mathrm{SINR}}_R^i)}^N}-1$

Wherein, M represents transmitting terminal antenna number, and N represents receiving terminal antenna number;

S3: the channel capacity C calculating three kinds of antenna modes respectively _sISO, C _tDand C _sM, computing formula is:

C _SISO＝log ₂(1+SINR _SISO)

C _TD＝log ₂(1+SINR _TD)

C _SM＝M×log ₂(1+SINR _SM)

S4: calculate judgement factor alpha, computing formula is:

$\mathrm{\&alpha;}=\frac{C_{SISO}}{max(C_{TD},C_{SM})}$

S5: if α>=α _th, adopt single antenna pattern; If not, then judge whether C further _tD>=C _sM, if so, then adopt transmitting diversity pattern, otherwise adopt space multiplexing mode.

2. multi-antenna adaptive dispatching method according to claim 1, is characterized in that, the signal to noise ratio in step S1 computing formula be:

${\mathrm{SINR}}_R^i=\frac{\mathrm{\&beta;}\&CenterDot;P_{SRS}\&CenterDot;\underset{j=1}{\overset{Q}{\&Sigma;}}{p}_c^j}{S_I+N_{0}B}$

Wherein, P _sRSfor the received power at node place district pilots measuring-signal (SoundReferenceSignal, SRS); for the channel power of a jth subcarrier is composed, Q is transmission subcarrier number, and B represents system bandwidth, and β is channel fading coefficient, N ₀for the power spectral density of interchannel noise, S _irepresent interference power.

3. multi-antenna adaptive dispatching method according to claim 1, is characterized in that, decision threshold α in step S5 _thspan be 0.85≤α _th< 1.