CN103152763B - Wireless admission control method and device - Google Patents

Abstract

The invention discloses a wireless admission control method and a device and relates to the field of wireless access. The wireless admission control method includes the steps: adopting a Rice fading model to confirm a bit error rate according to a mobile speed of a user requesting for accessing to network, confirming a bit speed of the user requesting for accessing to the network according to the bit error rate and a request data speed, and confirming whether to admit the user requesting for accessing to the network or not according to the size relationship between a sum of a bit speed of a user accessed to the network and the bit speed of the user requesting for accessing to the network and transmission capacity of a community. The wireless admission control method and the device capable of considering affects of the bit error rate to the data speed during high-speed mobile of the user and guaranteeing quality of business service.

Description

A kind of wireless acceptance controlling method and device

Technical field

The present invention relates to wireless access technology field, particularly the wireless acceptance controlling method of one and device.

Background technology

Along with the fast development of high-speed railway, increasing user selects this vehicles quickly and easily, and this brings new challenge to communications network deployment.

Current wireless admission control mechanism is all carry out studying based on the vehicular speeds situation lower than 200km/h in normal cellular network.In cellular networks, have many indirectly paths between transmitter and receiver, therefore, admission control mechanism also adopts the Rayleigh fading model adapted with it.Further, in cellular cell, the translational speed of user is all relatively slow, and therefore, admission control mechanism ignores the translational speed of user usually.

But under high-speed railway environment, different communities is zonal distribution along railway line, and user moves towards the direction substantially determined fast with the speed more than 300km/h, asks the arrival Relatively centralized of access service and there is diversity.Further, base station is positioned near railway line, except having many indirectly paths between transmitter and receiver, also has a direct los path.This will cause a series of new problem, the channel conditions of such as serious Doppler frequency shift, switching and dynamic change frequently fast.

Realizing in process of the present invention, inventor finds that prior art at least exists following problem:

Base station under high-speed railway environment and community distribute and user velocity, all there occurs very large change relative to normal cellular network, and the wireless admission control mechanism proposed based on normal cellular network is not suitable for high-speed railway environment.Therefore, be necessary to propose a kind of wireless admission control mechanism being applicable to high-speed railway environment.

Summary of the invention

In order to propose a kind of wireless admission control mechanism being applicable to high-speed railway environment, embodiments provide a kind of wireless acceptance controlling method and device.Described technical scheme is as follows:

A kind of wireless acceptance controlling method, described method comprises:

According to the translational speed of the user of request access network, adopt this fading model determination bit error rate of Lay;

According to bit error rate and requested data rates, determine the bit rate of the user of described request access network;

According to the magnitude relationship of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network.

Wherein, the translational speed of the described user according to request access network, adopts this fading model determination bit error rate of Lay, specifically comprises:

According to the translational speed of the user of request access network, calculate the channel impulse response of los path and obstructed path respectively;

According to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna, and calculate the discrete Fourier transform (DFT) of channel gain between described dual-mode antenna according to the channel impulse response between described dual-mode antenna;

According to discrete Fourier transform (DFT) and the error function of channel gain between described dual-mode antenna, calculate bit error rate.

Wherein, described according to bit error rate and requested data rates, determine the bit rate of the user of described request access network, specifically comprise:

According to bit error rate, determine checking symbol expense;

According to checking symbol expense and header overhead, the overhead that in calculated data bag, every bit is corresponding;

According to described request data rate and overhead corresponding to described every bit, determine the bit rate of the user of described request access network.

Wherein, the magnitude relationship of the bit rate sum of the user of the described bit rate according to network existing subscriber and described request access network and the transmission capacity of community, determines whether the user receiving described request access network, specifically also comprises:

According to magnitude relationship and the service priority of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network.

Wherein, the magnitude relationship of the bit rate sum of the user of the described bit rate according to network existing subscriber and described request access network and the transmission capacity of community and service priority, determine whether the user receiving described request access network, specifically comprise:

If what the user of described request access network was corresponding is service switchover, when the bit rate sum of the bit rate of network existing subscriber and the user of described request access network is greater than the transmission capacity of community, compression priority is lower than or/and equal the self-adapted service bandwidth of described service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of described request access network, if met, receive the user of described request access network, if do not met, the user of the access network that rejects said request.

A kind of wireless admission control device, described device comprises:

Bit error rate determination module, for the translational speed of the user according to request access network, adopts this fading model determination bit error rate of Lay;

User's bit rate determination module, for according to bit error rate and requested data rates, determines the bit rate of the user of described request access network;

Call access control module, for the magnitude relationship according to the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determines whether the user receiving described request access network.

Wherein, described bit error rate determination module, specifically for

According to the translational speed of the user of request access network, calculate the channel impulse response of los path and obstructed path respectively;

According to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna, and calculate the discrete Fourier transform (DFT) of channel gain between described dual-mode antenna according to the channel impulse response between described dual-mode antenna;

According to discrete Fourier transform (DFT) and the error function of channel gain between described dual-mode antenna, calculate bit error rate.

Wherein, described user's bit rate determination module, specifically for

According to bit error rate, determine checking symbol expense;

According to checking symbol expense and header overhead, the overhead that in calculated data bag, every bit is corresponding;

According to described request data rate and overhead corresponding to described every bit, determine the bit rate of the user of described request access network.

Wherein, described call access control module, also for

According to magnitude relationship and the service priority of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network.

Wherein, described call access control module, specifically for

If what the user of described request access network was corresponding is service switchover, when the bit rate sum of the bit rate of network existing subscriber and the user of described request access network is greater than the transmission capacity of community, compression priority is lower than or/and equal the self-adapted service bandwidth of described service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of described request access network, if met, receive the user of described request access network, if do not met, the user of the access network that rejects said request.

The beneficial effect of the technical scheme that the embodiment of the present invention provides is:

By the translational speed of the user according to request access network, adopt this fading model determination bit error rate of Lay; According to bit error rate and requested data rates, determine the bit rate of the user asking access network; According to bit rate and the request bit rate sum of user of access network and the magnitude relationship of the transmission capacity of community of network existing subscriber, determine whether the user receiving request access network, when considering user's high-speed mobile, bit error rate is on the impact of data rate, can ensure QoS.In addition, when bandwidth resources are not enough, carry out call access control based on different service priority, service switchover drop rate can be reduced.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the network architecture schematic diagram of the high-speed railway communication system layering that the embodiment of the present invention 1 provides;

Fig. 2 is the wireless acceptance controlling method flow chart that the embodiment of the present invention 1 provides;

Fig. 3 is the wireless acceptance controlling method flow chart of the introducing service priority that the embodiment of the present invention 1 provides;

Fig. 4 is the relation schematic diagram of the bit error rate that provides of the embodiment of the present invention 1 and translational speed;

Fig. 5 is the relation schematic diagram of blocking rate and translational speed under QPSK modulation system that the embodiment of the present invention 1 provides;

Fig. 6 is the relation schematic diagram of blocking rate and translational speed under the 16-QAM modulation system that provides of the embodiment of the present invention 1;

Fig. 7 is the relation schematic diagram of drop rate and translational speed under the QPSK modulation system that provides of the embodiment of the present invention 1;

Fig. 8 is the relation schematic diagram of drop rate and translational speed under the 16-QAM modulation system that provides of the embodiment of the present invention 1;

Fig. 9 is the wireless admission control device structural representation that the embodiment of the present invention 2 provides.

Embodiment

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

Embodiment 1

See Fig. 1, high-speed railway communication system adopts the network architecture of layering.Due to be distributed in Along Railway different districts between switching frequently occur, switch frequently to reduce, need the coverage expanding community, therefore, the present embodiment proposes the solution of distributed base station.Base station comprises: BBU (Building Baseband Unit, indoor baseband processing unit) and RRU (Radio Remote Unit, Remote Radio Unit).BBU is positioned in base station, and RRU can downline flexible deployment.Multiple RRU can be connected with a BBU respectively by optical fiber, and RRU is connected with neighbouring transmitting antenna by coaxial cable again.BBU and RRU is used for processing baseband signal and radiofrequency signal respectively, and baseband signal and radiofrequency signal can separately be processed.Optical fiber is used for transmission base band between BBU and RRU, and avoid the long range propagation of radiofrequency signal, loss is reduced.In addition, penetrating the loss in compartment to overcome signal, on train top, VS (Vehicular Station, Vehicle mounted station) being installed, being wirelessly connected with RRU.In order to ensure the reliable communication between RRU and train, at first segment and top, final section compartment, a Vehicle mounted station is respectively installed.As the case may be, these two Vehicle mounted stations both can work alone, also can collaborative work.Meanwhile, often save in compartment install a repeater (Repeater), user can be linked into network by repeater.

Based on the above-mentioned network architecture, see Fig. 2, present embodiments provide a kind of wireless acceptance controlling method, the method comprises:

101: according to the translational speed of the user of request access network, adopt this fading model determination bit error rate of Lay;

Step 101 specifically comprises step 1011-1013:

1011; According to the translational speed of the user of request access network, calculate the channel impulse response of los path and obstructed path respectively;

Because the increase bit error rate along with translational speed will rise, useful data bit will be caused to reduce, the service quality of different business will be had a strong impact on.Therefore, under high-speed railway environment, the present embodiment has taken into full account the impact of translational speed on bit error rate of user.

1) according to the translational speed of the user of request access network, the channel impulse response in following formulae discovery sighting distance (LOS, Line-of-Sight) path can specifically be adopted:

$h_{i,j}^{\mathrm{LOS}}\left(t\right)=\sqrt{G_t\left({\mathrm{\θ}}_t\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t\right)\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r\right)}\exp (j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r\right)+{\mathrm{\Φ}}_{\mathrm{LOS}})\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r-{\mathrm{\θ}}_v)t\right)---\left(1\right)$

Wherein, represent the channel impulse response of los path, θ _twhat represent LOS path leaves angle, G _t(θ _t) represent transmitter antenna gain (dBi), d _jrepresent the distance of a jth transmitting antenna to reference antenna, λ represents carrier wavelength, θ _rrepresent the angle of arrival of los path, G _r(θ _r) represent receiving antenna gain, d _irepresent the distance of i-th reception antenna to reference antenna, Φ _lOSrepresent the phase place of los path, v represents the translational speed of user, θ _vrepresent the angle of velocity vector.T represents the time.Exp represents with e to be the exponential function at the end.It should be noted that, the first letter j in exp function represents imaginary number, and j in addition all represents a jth transmitting antenna.

2) according to the translational speed of the user of request access network, the channel impulse response in following formulae discovery non line of sight (NLOS, Non-Line-of-Sight) path can specifically be adopted:

$h_{i,j}^{\mathrm{NLOS}}\left(t\right)=\underset{n=1}{\overset{P}{\mathrm{\Σ}}}\sqrt{P_n}\sqrt{G_t\left({\mathrm{\θ}}_t^n\right)}\exp \left(j\right[\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t^n\right)+{\mathrm{\Φ}}_n\left]\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r^n\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r^n\right)\right)\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r^n-{\mathrm{\θ}}_v)t\right)---\left(2\right)$

Wherein, represent the channel impulse response of obstructed path, P is the number of obstructed path (or indirect path), P _nrepresent the power of n-th obstructed path, what represent n-th obstructed path leaves angle, represent transmitter antenna gain (dBi), Φ _nrepresent the phase place of n-th obstructed path, represent the angle of arrival of n-th obstructed path, represent receiving antenna gain.Other symbol implications are identical with formula (1), repeat no more here.

1012: according to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna, and calculate the discrete Fourier transform (DFT) of channel gain between dual-mode antenna according to the channel impulse response between dual-mode antenna;

Because base station is positioned near railway line under high-speed railway environment, except having many indirectly paths between transmitter and receiver, also has a direct los path.Therefore, the present embodiment adopts rician fading channel to describe the channel characteristics of high-speed railway communication system.

Wherein, according to channel impulse response and the Rice factor of los path and obstructed path, the channel impulse response between following formulae discovery dual-mode antenna can specifically be adopted:

$h_{i,j}\left(t\right)=\sqrt{\frac{K}{1+K}}{h}_{i,j}^{\mathrm{LOS}}\left(t\right)+\sqrt{\frac{1}{1+K}}{h}_{i,j}^{\mathrm{NLOS}}\left(t\right)---\left(3\right)$

Wherein, h _{i, j}t () represents the channel impulse response between a jth transmitting antenna and i-th reception antenna, with be the channel impulse response of los path and obstructed path respectively, K is Rice factor, represents the energy of sighting distance composition and the ratio of the gross energy of scattering non line of sight composition.Other symbol implications are identical with formula (1), repeat no more here.

Wherein, adopt fourier transform method of the prior art, the channel impulse response between dual-mode antenna calculates the discrete Fourier transform (DFT) of channel gain between dual-mode antenna, is set to H _{i, j}(k).

1013: according to discrete Fourier transform (DFT) and the error function of channel gain between dual-mode antenna, calculate bit error rate.

This step specifically can adopt following formulae discovery bit error rate:

$P_b=\frac{2(1-\frac{1}{\sqrt{2^a}})}{\mathrm{N\α}}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\mathrm{erfc}\left(\sqrt{\frac{1.5r_s\underset{i=1}{\overset{2}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{\left|H_{i,j}\left(k\right)\right|}^2}{2R_c(2^{\mathrm{\α}}-1)}}\right)---\left(4\right)$

Wherein, P _bbe bit error rate, N represents number of subcarriers, and each symbol contains α bit, and erfc (x) is error function, is defined as r _s=E _s/ N ₀, E _sand N ₀represent symbol energy and the noise energy of transmitter respectively, R _cit is the code check of SFBC system.Other symbol implications are identical with formula (1), repeat no more here.

Formula (4) can approximate representation be:

$P_b=\frac{0.2}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\exp (-\frac{1.6r_s\underset{i=1}{\overset{2}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{\left|H_{i,j}\left(k\right)\right|}^2}{2R_c(2^{\mathrm{\α}}-1)})---\left(5\right)$

Wherein, each symbol implication is identical with formula (4), repeats no more here.

102: according to bit error rate and requested data rates, determine the bit rate of the user asking access network;

Step 102 specifically comprises step 1021-1023:

1021: according to bit error rate, determine checking symbol expense;

Suppose that channel coding scheme adopts RS (Reed Solomon) code, this step specifically can adopt following formula to determine:

N _check＝2N _error＝2N _sP _s＝2N _s[1-(1-P _b) ^d](6)

Wherein, N _checkrepresent checking symbol expense, N _errorrepresent the symbolic number made a mistake, N _srepresent the symbol quantity that data include, P _srepresent symbol error rate, P _brepresent bit error rate, d represents the amount of bits that a symbol contains.

1022: according to checking symbol expense and header overhead, the overhead that in calculated data bag, every bit is corresponding;

This step specifically can adopt following formulae discovery:

Q _overhead＝(H _b+dN _check)/L (7)

Wherein, Q _overheadrepresent the overhead that every bit is corresponding, H _brepresent header overhead, d represents that the amount of bits that a symbol contains, L represent that packet comprises the quantity of bit.

1023: according to requested data rates and overhead corresponding to every bit, determine the bit rate of the user asking access network.

b _r′＝b _r+Q _overheadb _r(8)

Wherein, b _rthe bit rate of the user of ' expression request access network, b _rrepresent requested data rates, Q _overheadrepresent the overhead that every bit is corresponding.

103: according to bit rate and the request bit rate sum of user of access network and the magnitude relationship of the transmission capacity of community of network existing subscriber, determine whether the user receiving request access network.

Concrete, if the bit rate sum of the user of the bit rate of network existing subscriber and request access network is less than or equal to the transmission capacity of community, then receive the user of request access network, otherwise, if the bit rate sum of the user of the bit rate of network existing subscriber and request access network is greater than the transmission capacity of community, then the user of refusal request access network.

Formula is expressed as follows:

$\underset{i}{\mathrm{\Σ}}{b}_i+b_r^{\′}\≤C_{\mathrm{total}}---\left(9\right)$

Wherein, b _irepresent the bit rate of existing i-th user in network, b _rthe bit rate of the user of ' expression request access network, C _totalrepresent the transmission capacity of community.

In addition, in the high-speed railway communication scenes of reality, often there will be the situation that bandwidth resources are not enough.On the one hand, because hundreds of user's integrated distribution are in railway car, make traffic carrying capacity comparatively large, certain pressure can be caused to single subdistrict.On the other hand, train in the process of moving, often can meet with the train on opposite.When rows of parking stall is when the overlay area of certain community, if the train on opposite just also drives same overlay area into, on the train of opposite, the service needed of well afoot transfers to new community, and the traffic carrying capacity of this community can be caused to increase considerably.The user of above two kinds of request access networks is called new user and switches user, and corresponding business is respectively new business and service switchover.But due to the total bandwidth resource-constrained of community, the business of component requests access will be rejected.

How when bandwidth resources are not enough, ensure to receive business as much as possible, the scheme that the present embodiment provides " according to the bit rate of network existing subscriber and the request bit rate sum of user of access network and the magnitude relationship of the transmission capacity of community and service priority, determining whether to receive the user asking access network ".Namely, if what the user of request access network was corresponding is service switchover, when the bit rate of network existing subscriber and the bit rate sum of user of request access network are greater than the transmission capacity of community (also bandwidth resources enough time), compression priority is lower than or/and equal self-adapted service (i.e. the business of the rate-compatible) bandwidth of service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of request access network, if met, receive the user of request access network, if do not met, the user of refusal request access network.

Usual user uses voice, data and video three kinds of business, according to 3GPP (The 3rd Generation PartnershipProject, third generation partner program) quality of service architecture, when considering time delay, delay variation and transmission stability, the priority of usual voice is higher than the priority of video, and the priority of video is higher than the priority of data.Those skilled in the art can according to actual needs, and the priority of setting miscellaneous service, the business related in the present embodiment includes but not limited to voice, video, data etc.

See Fig. 3, introduce the wireless acceptance controlling method of service priority, following flow process specifically can be adopted to realize:

When multiple business request access network, will process successively according to service priority order.For the business of request access, first judge whether this business is service switchover, if not, illustrate that this business is new business, if now there are enough bandwidth resources, this new business will be accepted, otherwise get clogged, if this business is service switchover, if now there are enough bandwidth resources, this service switchover will be accepted, if bandwidth resources are not enough, by to priority lower than or/and self-adapted service (i.e. the business of the rate-compatible) bandwidth equaling this business is compressed successively, until the remaining bandwidth after compression can meet the bit rate (being also minimum quality of service) of the user of request access network, compression bandwidth is out supplied to the service switchover of request access, if compression bandwidth is out equal to or greater than the bandwidth of the minimum quality of service demand of the service switchover of request access, this service switchover will be accepted, otherwise will go offline.

The wireless acceptance controlling method that the present embodiment provides, be applicable to adopt SFBC (Space-Frequency Block Coding, space-frequency block codes) OFDM (Orthogonal Frequency Division Multiplexing, OFDM) system.Below to have N _tindividual transmitting antenna and N _rthe ofdm system of the employing SFBC technology of individual reception antenna, N number of subcarrier is that example is simply introduced.

At receiving terminal, the Received signal strength formula on i-th reception antenna is expressed as follows:

$R_i=\underset{j=1}{\overset{N_T}{\mathrm{\Σ}}}{H}_{i,j}{T}_j+n_i,1\≤i\≤N_R---\left(10\right)$

Wherein, R _irepresent the Received signal strength on i-th reception antenna, T _jrepresent transmitting on a jth antenna; represent N × N diagonal matrix, its element H _{i, j}k () is the discrete Fourier transform (DFT) of channel gain between a jth transmitting antenna and i-th reception antenna; n _irepresent additive white Gaussian noise.

After input data sequence converts parallel fo to, produce data block T={t (0), t (1) ..., t (N-1) }.Be located in high-speed railway communication system the antenna technology adopting 2 × 2, define sub-block t respectively ₁(k)=(t (2k)-t ^*(2k+1)) and t ₂(k)=(t (2k+1) t ^*(2k)), subscript ^*represent complex conjugation operator.Therefore, the orthogonal block code for two antennas can be expressed as [t ₁(k) ^tt ₂(k) ^t], k=0 ..., N/2-1.Received signal strength formula on i-th reception antenna is expressed as follows:

R _i＝H _i，1T ₁+H _i，2T ₂+n _i，1≤i≤2(11)

In addition, suppose can know channel condition information at receiving terminal.Use Maximum Likelihood Detection method to carry out decoding to received signal, decoded signal is formulated as follows:

$\tilde{R}\left(2k\right)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}(H_{i,1}^{*}\left(2k\right)R_i\left(2k\right)+H_{i,2}\left(2k\right)R_i^{*}(2k+1))---\left(12\right)$

$\tilde{R}(2k+1)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}(H_{i,2}^{*}(2k+1)R_i\left(2k\right)-H_{i,1}(2k+1)R_i^{*}(2k+1))$

Meanwhile, suppose the channel gain approximately equal of two adjacent sub-carriers, can H be expressed as _{i, 1}(2k)=H _{i, 1}(2k+1) and H _{i, 2}(2k)=H _{i, 2}(2k+1).Therefore, decoded signal is formulated as follows:

$\tilde{R}\left(2k\right)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}({\left|H_{i,1}\left(2k\right)\right|}^2+{\left|H_{i,2}\left(2k\right)\right|}^2)t\left(2k\right)+\mathrm{\ω}\left(2k\right)---\left(13\right)$

$\tilde{R}(2k+1)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}({\left|H_{i,1}\left(2k\right)\right|}^2+{\left|H_{i,2}\left(2k\right)\right|}^2)t(2k+1)+\mathrm{\ω}(2k+1)$

Wherein, ω (2k) and ω (2k+1) is noise, is formulated as follows:

$\mathrm{\ω}\left(2k\right)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}(H_{i,1}^{*}\left(2k\right)n_i\left(2k\right)+H_{i,2}\left(2k\right)n_i^{*}(2k+1))---\left(14\right)$

$\mathrm{\ω}(2k+1)=\underset{i=1}{\overset{2}{\mathrm{\Σ}}}(H_{i,2}^{*}\left(2k\right)n_i\left(2k\right)-H_{i,1}\left(2k\right)n_i^{*}(2k+1))$

The present embodiment combines the performance that wireless acceptance controlling method is assessed in emulation below.Consider the business of voice, data and video three types, use Poisson process to describe the arrival situation of different business, the data rate of request is 64,128 and 512Kbps respectively.In addition, other simulation parameter is set to N=128, K=6dB, R _c=1, r _s=20, L=4095bits, H _b=16bits and C _total=40Mbps, can with reference to " Spatial channel model for multiple input multiple output (MIMO) simulations, " 3GPP TR 25.996version 9.0.0 about the parameter value of rician fading channel in formula (1) and (2).

(1) bit error rate

Fig. 4 shows the relation under different modulating mode between bit error rate and translational speed.Visible, along with the increase of translational speed, bit error rate rises all gradually.In addition, QPSK has lower bit error rate than 16-QAM.Reason is to worsen in high-speed mobile scene lower channel situation trend, and now high-order modulating is poorer than the performance of low order on the contrary.

(2) blocking rate

Simulating scenes is: rows of car is run at high speed, and the arrival rate of voice, data and video traffic is 2,0.5 and 0.1 business per second respectively, and average service time obeys the exponential distribution that average is 60,300 and 600 seconds respectively, and simulation time is 700 seconds.

Fig. 5 shows under QPSK modulation system, the relation of blocking rate and translational speed under two kinds of wireless admission control mechanisms.Along with the increase of translational speed, the blocking rate of two kinds of wireless admission control mechanisms increases all gradually.Reason is, these two kinds of wireless admission control mechanisms all consider the impact of bit error rate, in order to the data rate of obtaining request, needs to transmit extra overhead-bits, causes that each business is actual occupies more bandwidth resources.Therefore, the service quality of business can be guaranteed; In addition, compare the wireless admission control mechanism only considering bit error rate, consider that the mechanism of bit error rate and service priority has lower blocking rate simultaneously.Reason is because the priority of speech business is the highest and its data rate is minimum, network is received more speech business.

Fig. 6 describes under 16-QAM modulation system, the relation of blocking rate and translational speed under two kinds of wireless admission control mechanisms.Can find out, along with the increase of translational speed, the blocking rate of two kinds of wireless admission control mechanisms increases all gradually, consider the wireless admission control mechanism of bit error rate and service priority than only considering that the mechanism of bit error rate has lower blocking rate, the same with under QPSK modulation system of reason simultaneously; Unlike, the blocking rate of two kinds of wireless admission control mechanisms is all higher than the blocking rate under QPSK mode.Reason is, under high-speed mobile environment, when channel condition is deteriorated, the bit error rate under 16-QAM mode, higher than the bit error rate of QPSK, makes extra overhead-bits increase considerably.

(3) drop rate

Simulating scenes is: two row trains are run at high speed in opposite directions, will enter same community at driving process.The arrival rate of voice, data and video traffic on two row trains is 2,0.25 and 0.05 business per second all respectively, and average service time obeys the exponential distribution that average is 40,200 and 500 seconds all respectively, and simulation time is 600 seconds.

Under Fig. 7 shows QPSK modulation system, the relation of drop rate and translational speed under two kinds of wireless admission control mechanisms.Along with the increase of translational speed, the blocking rate of two kinds of wireless admission control mechanisms increases all gradually.Reason is the impact that these two kinds of wireless admission control mechanisms all consider bit error rate, in order to the data rate of obtaining request, needs to transmit extra overhead-bits, causes that each business is actual occupies more bandwidth resources.Therefore, better service quality can be obtained; In addition, consider the wireless admission control mechanism of bit error rate and service priority than only considering that the mechanism of bit error rate has lower drop rate simultaneously.Be on the one hand because the priority of speech business is the highest and its data rate is minimum, network is received more speech business, be because when bandwidth resources are not enough on the other hand, the fractional bandwidth of compression self-adapted service can receive a part of service switchover.

Under Fig. 8 describes 16-QAM modulation system, the relation of drop rate and translational speed under two kinds of wireless admission control mechanisms.Can find out, along with the increase of translational speed, the drop rate of two kinds of wireless admission control mechanisms increases all gradually, consider the wireless admission control mechanism of bit error rate and service priority than only considering that the mechanism of bit error rate has lower drop rate, the same with under QPSK modulation system of reason simultaneously; Unlike, the drop rate of two kinds of wireless admission control mechanisms is all higher than the drop rate under QPSK mode.Reason is under high-speed mobile environment, and when channel conditions deteriorate, the bit error rate under 16-QAM mode, higher than the bit error rate of QPSK, makes extra overhead-bits increase considerably.

The wireless acceptance controlling method that the present embodiment provides, when considering user's high-speed mobile, bit error rate is on the impact of data rate, can ensure QoS.In addition, when bandwidth resources are not enough, carry out call access control based on different service priority, service switchover drop rate can be reduced.

Embodiment 2

See Fig. 9, present embodiments provide a kind of wireless admission control device, this device comprises:

Bit error rate determination module 201, for the translational speed of the user according to request access network, adopts this fading model determination bit error rate of Lay;

User's bit rate determination module 202, for according to bit error rate and requested data rates, determines the bit rate of the user asking access network;

Call access control module 203, for according to the bit rate of network existing subscriber and the request bit rate sum of user of access network and the magnitude relationship of the transmission capacity of community, determines whether to receive the user asking access network.

Wherein, bit error rate determination module 201, specifically for

According to the translational speed of the user of request access network, calculate the channel impulse response of los path and obstructed path respectively; According to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna, and calculate the discrete Fourier transform (DFT) of channel gain between dual-mode antenna according to the channel impulse response between dual-mode antenna; According to discrete Fourier transform (DFT) and the error function of channel gain between dual-mode antenna, calculate bit error rate.

Wherein, user's bit rate determination module 202, specifically for

According to bit error rate, determine checking symbol expense; According to checking symbol expense and header overhead, the overhead that in calculated data bag, every bit is corresponding; According to requested data rates and overhead corresponding to every bit, determine the bit rate of the user asking access network.

Wherein, call access control module 203, also for

According to the bit rate of network existing subscriber and the request bit rate sum of user of access network and the magnitude relationship of the transmission capacity of community and service priority, determine whether to receive the user asking access network.

Wherein, call access control module 203, specifically for

If what the user of request access network was corresponding is service switchover, when the bit rate of network existing subscriber with when asking the bit rate sum of the user of access network to be greater than the transmission capacity of community, compression priority is lower than or/and equal the self-adapted service bandwidth of service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of request access network, if met, receive the user of request access network, if do not met, the user of refusal request access network.

The wireless admission control device that the present embodiment provides and embodiment of the method belong to same design, and its specific implementation process refers to embodiment of the method and repeats no more here.

The wireless admission control device that the present embodiment provides, when considering user's high-speed mobile, bit error rate is on the impact of data rate, can ensure QoS.In addition, when bandwidth resources are not enough, carry out call access control based on different service priority, service switchover drop rate can be reduced.

One of ordinary skill in the art will appreciate that all or part of step realizing above-described embodiment can have been come by hardware, the hardware that also can carry out instruction relevant by program completes, described program can be stored in a kind of computer-readable recording medium, the above-mentioned storage medium mentioned can be read-only memory, disk or CD etc.

The foregoing is only preferred embodiment of the present invention, not in order to limit 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 (6)

1. a wireless acceptance controlling method, is characterized in that, described method comprises:

According to the translational speed of the user of request access network, adopt this fading model determination bit error rate of Lay;

According to bit error rate and requested data rates, determine the bit rate of the user of described request access network;

According to the magnitude relationship of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network;

The translational speed of the described user according to request access network, adopts this fading model determination bit error rate of Lay, specifically comprises:

According to the movement speed v of the user of request access network, calculate the channel impulse response of los path respectively: $h_{i,j}^{\mathrm{LOS}}\left(t\right)=\sqrt{G_t\left({\mathrm{\θ}}_t\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t\right)\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r\right)}\exp (j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r\right)+{\mathrm{\Φ}}_{\mathrm{LOS}})\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r-{\mathrm{\θ}}_v)t\right)$ With the channel impulse response of obstructed path:

$h_{i,j}^{\mathrm{NLOS}}\left(t\right)=\underset{n=1}{\overset{P}{\mathrm{\Σ}}}\sqrt{P_n}\sqrt{G_t\left({\mathrm{\θ}}_t^n\right)}\exp \left(j\right[\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t^n\right)+{\mathrm{\Φ}}_n\left]\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r^n\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r^n\right)\right)\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r^n-{\mathrm{\θ}}_v)t\right);$

According to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna and the discrete Fourier transform (DFT) of channel gain between described dual-mode antenna is calculated according to the channel impulse response between described dual-mode antenna;

According to discrete Fourier transform (DFT) and the error function of channel gain between described dual-mode antenna, adopt formula $P_b=\frac{2(1-\frac{1}{\sqrt{2^{\mathrm{\α}}}})}{\mathrm{N\α}}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\mathrm{erfc}\left(\sqrt{\frac{1.5r_s\underset{i=1}{\overset{2}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{\left|H_{i,j}\left(k\right)\right|}^2}{2R_c(2^{\mathrm{\α}}-1)}}\right)$ Calculate bit error rate;

Wherein, represent the channel impulse response of los path, θ _twhat represent LOS path leaves angle, G _t(θ _t) represent transmitter antenna gain (dBi), d _jrepresent the distance of a jth transmitting antenna to reference antenna, λ represents carrier wavelength, θ _rrepresent the angle of arrival of los path, G _r(θ _r) represent receiving antenna gain, d _irepresent the distance of i-th reception antenna to reference antenna, Φ _lOSrepresent the phase place of los path, v represents the translational speed of user, θ _vrepresent the angle of velocity vector, t represents the time, and exp represents with e to be the exponential function at the end, represent the channel impulse response of obstructed path, P is the number of obstructed path or indirect path, P _nrepresent the power of n-th obstructed path, what represent n-th obstructed path leaves angle, represent transmitter antenna gain (dBi), Φ _nrepresent the phase place of n-th obstructed path, represent the angle of arrival of n-th obstructed path, represent receiving antenna gain, h _i,jt () represents the channel impulse response between a jth transmitting antenna and i-th reception antenna, with be the channel impulse response of los path and obstructed path respectively, K is Rice factor, represents the energy of sighting distance composition and the ratio of the gross energy of scattering non line of sight composition, P _bbe bit error rate, N represents number of subcarriers, and each symbol contains α bit, and erfc (x) is error function, is defined as r _s=E _s/ N ₀, E _sand N ₀represent symbol energy and the noise energy of transmitter respectively, R _cit is the code check of SFBC system;

Described according to bit error rate and requested data rates, determine the bit rate of the user of described request access network, specifically comprise:

Adopt on the basis of RS code at hypothesis channel coding scheme, according to bit error rate, utilize formula N _check=2N _error=2N _sp _s=2N _s[1-(1-P _b) ^d], determine checking symbol expense;

According to checking symbol expense and header overhead, adopt formula Q _overhead=(H _b+ dN _checkthe overhead that in)/L calculated data bag, every bit is corresponding;

According to described request data rate and overhead corresponding to described every bit, by formula b _r'=b _r+ Q _overheadb _r, determine the bit rate of the user of described request access network;

Wherein, N _checkrepresent checking symbol expense, N _errorrepresent the symbolic number made a mistake, N _srepresent the symbol quantity that data include, P _srepresent symbol error rate, P _brepresent bit error rate, d represents the amount of bits that a symbol contains, Q _overheadrepresent the overhead that every bit is corresponding, H _brepresent header overhead, d represents that the amount of bits that a symbol contains, L represent that packet comprises the quantity of bit, b _rthe bit rate of the user of ' expression request access network, b _rrepresent requested data rates, Q _overheadrepresent the overhead that every bit is corresponding.

2. method according to claim 1, it is characterized in that, the magnitude relationship of the bit rate sum of the user of the described bit rate according to network existing subscriber and described request access network and the transmission capacity of community, determines whether the user receiving described request access network, specifically also comprises:

According to magnitude relationship and the service priority of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network.

3. method according to claim 2, it is characterized in that, the magnitude relationship of the bit rate sum of the user of the described bit rate according to network existing subscriber and described request access network and the transmission capacity of community and service priority, determine whether the user receiving described request access network, specifically comprise:

If what the user of described request access network was corresponding is service switchover, when the bit rate sum of the bit rate of network existing subscriber and the user of described request access network is greater than the transmission capacity of community, compression priority is lower than or/and equal the self-adapted service bandwidth of described service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of described request access network, if met, receive the user of described request access network, if do not met, the user of the access network that rejects said request.

4. a wireless admission control device, is characterized in that, described device comprises:

Bit error rate determination module, for the translational speed of the user according to request access network, adopts this fading model determination bit error rate of Lay;

User's bit rate determination module, for according to bit error rate and requested data rates, determines the bit rate of the user of described request access network;

Call access control module, for the magnitude relationship according to the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determines whether the user receiving described request access network;

Described bit error rate determination module, specifically for

According to the movement speed v of the user of request access network, calculate the channel impulse response of los path respectively: $h_{i,j}^{\mathrm{LOS}}\left(t\right)=\sqrt{G_t\left({\mathrm{\θ}}_t\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t\right)\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r\right)}\exp (j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r\right)+{\mathrm{\Φ}}_{\mathrm{LOS}})\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r-{\mathrm{\θ}}_v)t\right)$ With the channel impulse response of obstructed path:

$h_{i,j}^{\mathrm{NLOS}}\left(t\right)=\underset{n=1}{\overset{P}{\mathrm{\Σ}}}\sqrt{P_n}\sqrt{G_t\left({\mathrm{\θ}}_t^n\right)}\exp \left(j\right[\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_j\sin \left({\mathrm{\θ}}_t^n\right)+{\mathrm{\Φ}}_n\left]\right)\×\sqrt{G_r\left({\mathrm{\θ}}_r^n\right)}\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}{d}_i\sin \left({\mathrm{\θ}}_r^n\right)\right)\×\exp \left(j\frac{2\mathrm{\π}}{\mathrm{\λ}}v\cos ({\mathrm{\θ}}_r^n-{\mathrm{\θ}}_v)t\right);$

According to channel impulse response and the Rice factor of los path and obstructed path, calculate the channel impulse response between dual-mode antenna and the discrete Fourier transform (DFT) of channel gain between described dual-mode antenna is calculated according to the channel impulse response between described dual-mode antenna;

According to discrete Fourier transform (DFT) and the error function of channel gain between described dual-mode antenna, adopt formula $P_b=\frac{2(1-\frac{1}{\sqrt{2^{\mathrm{\α}}}})}{\mathrm{N\α}}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\mathrm{erfc}\left(\sqrt{\frac{1.5r_s\underset{i=1}{\overset{2}{\mathrm{\Σ}}}\underset{j=1}{\overset{2}{\mathrm{\Σ}}}{\left|H_{i,j}\left(k\right)\right|}^2}{2R_c(2^{\mathrm{\α}}-1)}}\right)$ Calculate bit error rate;

Wherein, represent the channel impulse response of los path, θ _twhat represent LOS path leaves angle, G _t(θ _t) represent transmitter antenna gain (dBi), d _jrepresent the distance of a jth transmitting antenna to reference antenna, λ represents carrier wavelength, θ _rrepresent the angle of arrival of los path, G _r(θ _r) represent receiving antenna gain, d _irepresent the distance of i-th reception antenna to reference antenna, Φ _lOSrepresent the phase place of los path, v represents the translational speed of user, θ _vrepresent the angle of velocity vector, t represents the time, and exp represents with e to be the exponential function at the end, represent the channel impulse response of obstructed path, P is the number of obstructed path or indirect path, P _nrepresent the power of n-th obstructed path, what represent n-th obstructed path leaves angle, represent transmitter antenna gain (dBi), Φ _nrepresent the phase place of n-th obstructed path, represent the angle of arrival of n-th obstructed path, represent receiving antenna gain, h _i,jt () represents the channel impulse response between a jth transmitting antenna and i-th reception antenna, with be the channel impulse response of los path and obstructed path respectively, K is Rice factor, represents the energy of sighting distance composition and the ratio of the gross energy of scattering non line of sight composition, P _bbe bit error rate, N represents number of subcarriers, and each symbol contains α bit, and erfc (x) is error function, is defined as r _s=E _s/ N ₀, E _sand N ₀represent symbol energy and the noise energy of transmitter respectively, R _cit is the code check of SFBC system;

Described user's bit rate determination module, specifically for

Adopt on the basis of RS code at hypothesis channel coding scheme, according to bit error rate, utilize formula N _check=2N _error=2N _sp _s=2N _s[1-(1-P _b) ^d], determine checking symbol expense;

According to checking symbol expense and header overhead, adopt formula Q _overhead=(H _b+ dN _checkthe overhead that in)/L calculated data bag, every bit is corresponding;

According to described request data rate and overhead corresponding to described every bit, by formula b _r'=b _r+ Q _overheadb _r, determine the bit rate of the user of described request access network;

Wherein, N _checkrepresent checking symbol expense, N _errorrepresent the symbolic number made a mistake, N _srepresent the symbol quantity that data include, P _srepresent symbol error rate, P _brepresent bit error rate, d represents the amount of bits that a symbol contains, Q _overheadrepresent the overhead that every bit is corresponding, H _brepresent header overhead, d represents that the amount of bits that a symbol contains, L represent that packet comprises the quantity of bit, b _rthe bit rate of the user of ' expression request access network, b _rrepresent requested data rates, Q _overheadrepresent the overhead that every bit is corresponding.

5. device according to claim 4, is characterized in that, described call access control module, also for

According to magnitude relationship and the service priority of the bit rate of network existing subscriber and the bit rate sum of the user of described request access network and the transmission capacity of community, determine whether the user receiving described request access network.

6. device according to claim 5, is characterized in that, described call access control module, specifically for

If what the user of described request access network was corresponding is service switchover, when the bit rate sum of the bit rate of network existing subscriber and the user of described request access network is greater than the transmission capacity of community, compression priority is lower than or/and equal the self-adapted service bandwidth of described service switchover, judge after compressing, whether the untapped bandwidth in community meets the bit rate of the user of described request access network, if met, receive the user of described request access network, if do not met, the user of the access network that rejects said request.