CN106060916B - Gain adjusting method of multilayer heterogeneous cellular network based on traffic load - Google Patents

Abstract

The invention discloses a gain adjusting method of a multilayer heterogeneous cellular network based on traffic load. The method includes the following steps: acquiring distribution intensity [Lambda]k, base station transmission power Pk, bias factor Bk, average access rate Rth, access user number N, and power threshold Pth of energy collection of a current kth (k=1, 2,..., K) layer of base station; acquiring current rate coverage rate Rc; with the proviso that the coverage rate is kept unchanged, determining current average access rate can support the traffic load of the current period, and if the current average access rate can support the traffic load of the current period, then adjusting the base station bias factor to a bias factor which corresponds to high average collection energy, and if the current average access rate can not support the traffic load of the current period, then adjusting the base station bias factor to the bias factor which corresponds to the high average access rate. The gain adjusting method conducts testing verification through a double layer heterogeneous cellular network of one embodiment, and the verification result shows that when the current average access rate is sufficient to support the traffic load of the current period, compared with the bias-free heterogeneous cellular communication policy, the method has the beneficial effects of increasing energy collection gain.

Description

A kind of gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load

Technical field

The invention belongs to wireless communication technology field, more particularly, to a kind of multilayer heterogeneous honeybee based on flow load The gain adjusting method therefore of nest network.

Background technology

Isomery Cellular Networks (Heterogeneous cellular network, HCN) are referred in conventional macro base station (macro Base station) coverage in dispose that the mini site of several different types of low transmitting powers formed again it is many Layer network structure.Compared with the legacy cellular networking mode for carrying out individual layer covering only with macro base station, this network structure can Significantly improve capacity of cellular networks and expand the coverage of network.In addition, the concept of bias factor is introduced in heterogeneous network, System is allowd to allow user terminal to be linked on low-power website by adjusting bias factor, so as to alleviate significantly macro base station Load pressure.Further, since expense of the cost of single mini site much smaller than the single macro base station of operation, therefore facing nothing Under line number is according to the communication challenge of traffic demand explosive increase, being compared to increases the strategy of macro base station quantity, this network knot Structure drastically reduce the area networking cost and maintenance costs.

Therefore, in multilayer heterogeneous Cellular Networks, for the conditions of demand loaded according to different communication discharge in period of time, by certainly Adaptively adjusting bias factor causes whole system both to meet QoS requirement, and the rate gain or energy for improving system again is received The technology of diversity gain has active demand.

The content of the invention

Disadvantages described above or Improvement requirement for prior art, the invention provides a kind of multilayer based on flow load is different The gain adjusting method therefore of structure cellular network, its object is to the conditions of demand adjustment biasing according to the load of different communication discharge in period of time The factor, to improve rate gain or the collection of energy gain of system.

For achieving the above object, according to one aspect of the present invention, there is provided a kind of multilayer heterogeneous based on flow load The gain adjusting method therefore of cellular network, specifically includes following steps：

(1) according to current network information, obtain distribution density λ of kth layer base station_k, transmission power P_k, bias factor B_k, use Family access number N and average access rate R_th；Wherein, k=1,2 ..., K, K refer to the base station number of plies of isomery cellular network most It is big to be worth；

(2) user density λ is obtained according to user's access number N_u；

And according to distribution density λ_k, transmission power P_k, bias factor B_k, average access rate R_thAnd the user Density obtains present rate coverage rate R_c；

(3) in present rate coverage rate R_cUnder, bias factor is adjusted according to the flow load demand of present period, to adjust The rate gain of network or collection of energy gain.

Preferably, the gain adjusting method therefore of the above-mentioned multilayer heterogeneous cellular network based on flow load, its speed coverage rate

Wherein, λ_kIt is the distribution density of kth layer base station, B_kIt is the bias factor of kth layer base station, B_jIt is the inclined of jth layer base station Put the factor, P_kIt is the transmission power of kth layer base station,What is modeled is the shadow fading of kth layer base station,Refer to The load distribution of target BS, (n+1) be target base station service number of users, α is path-loss factor； Wherein, W is the network bandwidth；It is to ask expectation to process,It is to ask probability to process；

Wherein,Wherein, A_kRefer to use Family is linked into the probability on kth layer base station.

Preferably, the gain adjusting method therefore of the above-mentioned multilayer heterogeneous cellular network based on flow load, its step (3) adjustment The method of the station offsets factor is specific as follows：

If (3-1) current average access rate R_thMore than or equal to the flow load demand of present period, show when average Access rate supports the flow load demand of present period enough, on the premise of the speed coverage rate of present period is constant, protects The bias factor for holding the maximum base station of transmission power is constant, improve the transmission power station offsets less than this layer of transmission power because Son, until the average access rate of user is equal with the flow load demand of present period；Thus the bias factor of base station is adjusted The whole bias factor corresponding to high average collection energy, makes more users be unloaded on the less website of transmission power；And In the communication idle phase, energy is collected from interference base station；Wherein, interference base station includes providing the base station of maximal received power； This method not only alleviates the load pressure of macro base station, also improves the collection of energy gain of network simultaneously；

If (3-2) current average access rate R_thLess than the flow load demand of present period, show average access speed Rate not enough supports current flow load demand, on the premise of the speed coverage rate of network is constant, keeps transmission power minimum Base station bias factor it is constant, improve the bias factor of the transmission power base station bigger than this layer of base station power, until averagely connecing Enter speed equal with the flow load demand of present period；By the bias factor of base station is adjusted to high average access rate institute Corresponding bias factor, makes more users be linked on high-power transmitting base station so as to obtain higher average access rate； The program lifts the rate gain of network by sacrificing energy capture gain.

Preferably, the gain adjusting method therefore of the above-mentioned multilayer heterogeneous cellular network based on flow load, in the step (3) It is after carrying out gain-adjusted, also including (4) the step of user side averagely collects energy are obtained, specific as follows：

According to the power threshold P of collection of energy_th, reference distance be r₀When path loss L₀, obtain user and be linked into kth The energy P collected when on layer base station_{EH_k}；

And the probability A on kth layer base station is linked into according to user_kAnd the energy P_{EH_k}, obtain and meet flow load need The average collection energy P for asking_EH。

Preferably, the gain adjusting method therefore of the above-mentioned multilayer heterogeneous cellular network based on flow load, after gain-adjusted, when When the average access rate of user is equal with the flow load demand of present period, the collectable energy of user side is maximum；Now, Maximum average collection energy

Wherein, user is linked into the probability on kth layer base stationP_{EH_k}Refer to use The energy that family is collected when being linked on kth layer base station,

Wherein, r₀It is reference distance, L₀It is that reference distance is r₀When path loss, α is path-loss factor, P_thIt is energy The power threshold that amount is collected, refers to the minimum incident power of activation user side energy collection circuit, and its value is adopted according to user side Physical circuit set；

Wherein,

Energy that adjust before and after user side collect is calculated by above formula respectively can；Collected according to user side before and after regulation Energy computation results clearly can know, support the flow load conditions of demand of present period enough in current average access rate Under, the method provided by the present invention carries out gain-adjusted, and the energy that user collects increases, and shows the gain of present invention offer Control method can lift the collection of energy gain of user, with the beneficial effect for improving network energy efficiency.

In general, by the contemplated above technical scheme of the present invention compared with prior art, can obtain down and show Beneficial effect：

(1) gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load that the present invention is provided, according to current The flow load conditions of demand of period adjust bias factor to lift the related gain of network：When the flow load of network it is higher When, the corresponding bias factor of higher average access rate is selected, so as to lift the rate gain of network；Otherwise, using select compared with The high corresponding bias factor of average collection energy, so that reach the purpose of the collection of energy gain for lifting network；

(2) gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load that the present invention is provided, its preferred side In case, relatively low in the rate requirement of user, the average access rate of present period be enough to support that the flow load of present period is needed When asking, ensureing that the bias factor for improving little transmission power base station in the case that network rate coverage rate is constant is basic to meet Flow load demand, while the collection of energy gain of maximization network；On the one hand reduce the load pressure of big transmission power base station Power, on the other hand, increased the energy of system acquisition, so as to reduce the energy ezpenditure of system；

(3) gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load that the present invention is provided, its preferred side In case, higher in the service speed demand of user, the average access rate of present period is not enough to support the flow of present period During loading demand, more use are made in the bias factor for ensureing to improve big transmission power base station in the case that network coverage speed is constant Family is linked into high-power base station to obtain higher average access rate, and then improves the rate gain of network；

In general, it is proposed that above technical scheme and prior art in be not added with biasing (all layers of biasing because Son is disposed as multilayer heterogeneous Cellular communication strategy 1) and compares, and when flow load demand is relatively low, which has raising system capacity The beneficial effect of collecting amount, can lift the performance of whole network.

Description of the drawings

Fig. 1 is a system model schematic diagram comprising three layers of isomery cellular network；

Fig. 2 is a kind of gain-adjusted side of multilayer heterogeneous cellular network based on flow load provided in an embodiment of the present invention The flow chart of method；

During Fig. 3 is the embodiment of the present invention, the relation of bias factor and target access rate when speed coverage rate keeps constant Figure；

Fig. 4 is that current average access rate be enough to support under present period flow load conditions of demand, the embodiment of the present invention The method of offer be not added with bias two layers of isomery Cellular communication strategy collection energy comparison diagram.

Specific embodiment

In order that the objects, technical solutions and advantages of the present invention become more apparent, it is below in conjunction with drawings and Examples, right The present invention is further elaborated.It should be appreciated that specific embodiment described herein is only to explain the present invention, and It is not used in the restriction present invention.As long as additionally, technical characteristic involved in invention described below each embodiment Do not constitute conflict each other can just be mutually combined.

The present invention is to provide a kind of gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load, according to working as The flow load conditions of demand of front period adjust bias factor to lift the related gain of network：When the flow load of network it is higher When, using the corresponding bias factor of high average access rate, to lift the rate gain of network；Otherwise, using high average collection The corresponding bias factor of energy, to lift the collection of energy gain of network.

Shown in Fig. 1, it is a system model schematic diagram comprising three layers of isomery cellular network；In the network, user had been both Big transmission power base station can be directly accessed to obtain higher rate gain, it is also possible to cause user by adjusting bias factor Access on little transmission power website (AP as depicted, WIFI), to obtain higher collection of energy gain；In embodiment, institute Have base station and with obeying independent Poisson distribution per family, according to the characteristic of Poisson distribution, the geometric properties of any cell all with its In cell it is consistent, the analytical conclusions of one of cell can be expanded to all cells in cellular network.

Shown in Fig. 2, it is the gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load that embodiment is provided Flow chart, specifically includes following steps：

(1) system initialization is carried out, the essential information of current network is updated, is specifically included：Kth (k=1,2 .., K) layer Distribution density λ of base station_k, base station transmission power P_kAnd current bias factor B_k, number of users N that accesses and current Average access rate R_th；

(2) user density λ is obtained according to user's access number N_u；

And according to distribution density λ_k, transmission power P_k, bias factor B_k, average access rate R_thAnd the user is close Degree obtains current speed coverage rate R_c；

(3) judge whether current average access rate is more than or equal to the flow load of present period, cover speed is kept On the premise of lid rate is constant, the bias factor of the base station for if so, then keeping transmission power maximum is constant, improves transmission power than being somebody's turn to do The layer little station offsets factor of transmission power, until the flow load demand phase of the average access rate of user and present period Deng；

If it is not, the bias factor of the base station for then keeping transmission power minimum is constant, transmission power is improved than this layer of base station work( The bias factor of the big base station of rate, until average access rate is equal with the flow load demand of present period；With this by base station Bias factor is adjusted to the corresponding bias factor of high average access rate；

(4) the power threshold P according to collection of energy_th, reference distance be r₀When path loss L₀, obtain user and be linked into The energy P collected when on kth layer base station_{EH_k}；

And the probability A on kth layer base station is linked into according to user_kAnd the energy P_{EH_k}, obtain and meet flow load need The average collection energy asked.

In embodiment, when current average access rate is not enough to support the flow load of present period, little transmitting is reduced The bias factor of power base station causes more users to be linked on high-power base station to obtain higher average access rate, from And improve the rate gain of network；When current average access rate be enough to the flow load for supporting present period, little is improved The bias factor of power base station is penetrated so that more users are linked on small-power base station, although reduce the average access of user Speed, but improve the collection of energy gain of network.

Shown in Fig. 3, it is the graph of a relation between speed coverage rate and rate-valve value；In embodiment, K=2, i.e., with two layers of isomery As a example by Cellular Networks, relevant parameter is：Path-loss factor α=4, transmission power P of ground floor base station₁=12W, second layer base station Transmission power P₂=2W, ground floor base station distribution density λ₁=4 × 10^-5, second layer base station distribution density λ₂=20 × 10^-5, Bandwidth B=10WHz；Embodiment specifically provides the relation of bias factor and rate-valve value when speed coverage rate keeps constant, speed Rate coverage rate R_c=0.7, bias factor B=[010.67] dB, targeted rate T=1.05Mpbs, bias factor B=[0 0] dB, Corresponding targeted rate T=1.79Mpbs.

As can be seen from Figure 3：When speed covers speed keeps constant, the bias factor of second layer small-power base station is improved When, corresponding targeted rate will be reduced.

Shown in Fig. 4, it is two layers of isomery honeybee based on flow load when the present period flow load of embodiment offer is relatively low The gain adjusting method therefore of nest network compared with two layers of isomery Cellular communication strategy for being not added with biasing, both collection energy datum Simulation comparison figure；

Curve 10 instantiations of correspondence of Fig. 4, in 10 examples, partial parameters are identical, wherein, identical in each example Parameter and its numerical value are set to path-loss factor α=4, transmission power P of ground floor base station₁=12W, second layer base station send out Penetrate power P₂=2W, ground floor bias factor B₁=1, ground floor base station distribution density λ₁=4 × 10^-5, bandwidth B=10WHz, speed Rate coverage rate R_c=0.7, targeted rate when targeted rate, flow load when flow load is higher are relatively low is T₂= 1.3Mpbs；

In example, the data of different parameters are as shown in table 1 below, wherein λ₂Represent that the distribution of second layer base station of the present invention is close Degree, B₁₂It is the bias factor of contrast scheme second layer base station, B₂₂It is the bias factor of second layer base station of the present invention；

The data list of the different parameters of 1 1～example of example 10 of table

Can be seen that from the curve comparison analysis of Fig. 4：When the flow load of present period is relatively low, in contrast to be not added with biasing Isomery Cellular communication strategy, the gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load that embodiment is provided can The collection of energy gain of optimization system, improves the energy efficiency of whole network.

As it will be easily appreciated by one skilled in the art that the foregoing is only presently preferred embodiments of the present invention, not to The present invention, all any modification, equivalent and improvement made within the spirit and principles in the present invention etc. is limited, all should be included Within protection scope of the present invention.

Claims (4)

1. a kind of gain adjusting method therefore of the multilayer heterogeneous cellular network based on flow load, it is characterised in that specific as follows：

(1) according to current network information, obtain distribution density λ of kth layer base station_k, transmission power P_k, bias factor B_k, Yong Hujie Enter number N and average access rate R_th；Wherein, k=1,2 ..., K, K refer to the base station number of plies of multilayer heterogeneous cellular network most It is big to be worth；

(2) user density λ is obtained according to user's access number N_u；

And according to distribution density λ_k, transmission power P_k, bias factor B_k, average access rate R_thAnd the user density Obtain present rate coverage rate R_c；

(3) in present rate coverage rate R_cUnder, the station offsets factor is adjusted according to the flow load demand of present period, with Adjust rate gain or the collection of energy gain of the network；

Wherein, the speed coverage rate described in step (2)

$R_c=\underset{k=1}{\overset{K}{\Σ}}\underset{n\≥0}{\Σ}\frac{{\mathrm{\λ}}_{k}E\[{X_k}^{\frac{2}{\mathrm{\α}}}\]B_k^{\frac{2}{\mathrm{\α}}}{P}_k^{\frac{2}{\mathrm{\α}}}P({\mathrm{\Ψ}}_k=n+1)}{{\mathrm{\Σ}}_{j\∈K}{\mathrm{\λ}}_{j}E\[{X_j}^{\frac{2}{\mathrm{\α}}}\]P_j^{\frac{2}{\mathrm{\α}}}\[B_j^{\frac{2}{\mathrm{\α}}}+B_k^{\frac{2}{\mathrm{\α}}}F({\mathrm{\β}}_{n+1},\mathrm{\α},\frac{B_j}{B_k})\]};$

Wherein, λ_kIt is the distribution density of kth layer base station, B_kIt is the bias factor of kth layer base station, B_jBe jth layer base station biasing because Son, P_kIt is the transmission power of kth layer base station, X_kModeling be kth layer base station shadow fading, P (Ψ_k=n+1) refer to target base The load distribution stood, (n+1) be target base station service number of users, α is path-loss factor；Wherein, W It is bandwidth；E [] is to ask expectation to process, and P () is to ask probability to process.

2. gain adjusting method therefore as claimed in claim 1, it is characterised in that adjust described in step (3) station offsets because The method of son is specific as follows：

Judge current average access rate R_thWhether the flow load demand of present period is more than or equal to；

The bias factor of the base station for if so, then keeping transmission power maximum is constant, improves transmission power less than this layer of base station power Base station bias factor, until average access rate is equal with the flow load demand of present period, to lift the energy of network Amount collects gain；

If it is not, the bias factor of the base station for then keeping transmission power minimum is constant, transmission power is improved bigger than this layer of base station power Base station bias factor, until average access rate is equal with the flow load demand of present period, to lift the speed of network Rate gain.

3. gain adjusting method therefore as claimed in claim 1, it is characterised in that after the step (3) is also flat including obtaining The step of collecting energy (4), it is specific as follows：

According to the power threshold P of collection of energy_th, reference distance be r₀When path loss L₀, obtain user and be linked into kth layer base The energy P collected when on standing_{EH_k}；

And the probability A on kth layer base station is linked into according to user_kAnd the energy P_{EH_k}, obtain and meet flow load demand It is average to collect energy P_EH。

4. gain adjusting method therefore as claimed in claim 3, it is characterised in that after gain-adjusted, when the average access speed of user When rate is equal with the flow load demand of present period, the collectable average energy of user side is maximum；Maximum average collection energy

Wherein, user is linked into the probability on kth layer base station

$A_k=\frac{{\mathrm{\λ}}_{k}E\[{X_k}^{2/\mathrm{\α}}\]B_k^{2/\mathrm{\α}}{P}_k^{2/\mathrm{\α}}}{{\mathrm{\Σ}}_{j\∈K}{\mathrm{\λ}}_{j}E\[{X_j}^{2/\mathrm{\α}}\]B_j^{2/\mathrm{\α}}{P}_j^{2/\mathrm{\α}}};$

User is linked into the energy collect on kth layer base station

$P_{EH\_k}=\underset{j=1}{\overset{K}{\Σ}}{\mathrm{\λ}}_{j}E\[X_j\]{\mathrm{\πr}}_0^2{(P_j{L}_{0}E\[X_j\])}^{\frac{2}{\mathrm{\α}}}\×\left(P_{th}^{1-\frac{2}{\mathrm{\α}}}+\frac{\mathrm{\α}}{\mathrm{\α}-2}\left({(E\[p\left(a\right)\])}^{1-\frac{2}{\mathrm{\α}}}-P_{th}^{1-\frac{2}{\mathrm{\α}}}\right)\right);$

Wherein, r₀It is reference distance, L₀It is that reference distance is r₀When path loss, α is path-loss factor, P_thIt is that energy is received The power threshold of collection.