CN104168634B - Distributed user location aware cell method for closing for LTE-A cellular network - Google Patents

Abstract

The invention discloses a kind of distributed user location aware cell method for closing for LTE A cellular networks, LTE A down collaborations communication energy resources management domain, the feature in wireless communication of belonging to are：The cell that number of users is less and utilization rate is low can be preferentially closed, according to the number of users in the communication cell of periphery to promote the closing probability of the low cell of all utilization rates.By distribution situation of the user in communication cell, the optional adjacent base station range for receiving all transfer users of the cell is reduced, to reduce the algorithm complexity due to being brought using the very big algorithm of minimization.The advantage of the invention is that：In the case where ensureing user communication quality, according to the number of users in peripheral cell, dynamically adjusts and participate in the number of users threshold value that judgement cell is closed, improve closing number of cells, saved more multiple-energy-source；In conjunction with position of the user in cell, the optimal search range for receiving set is reduced, algorithm complexity is reduced.

Description

Distributed user location aware cell method for closing for LTE-A cellular network

Technical field

The present invention relates to a kind of distributing cell method for closing based on user location belongs in wireless communication under LTE-A The related field of row collaboration communication energy resources management.

Background technology

The fast development that have passed through decades, under the driving of ever-increasing data traffic demand, Information And Communication skill Art (Information and Communication Technology, ICT) just develops towards the direction for more focusing on performance, Related energy consumption is consequently increased.Recently a period of time, after recognizing following fact, energy consumption is promoted to an important view It inscribes and extensive discussions：The energy consumption of ICT industries accounts for the 3% of global energy consumption, and the discharge capacity of greenhouse gases accounts for the 2 of global emissions ~4%, and the energy consumption of ICT industries is increased with annual 15~20% speed, and every 5 years energy consumptions are doubled.In conventional wireless cellular In network, the energy consumption of base station (Base Stations, BS) accounts for 70% of total energy consumption or more, and it is worth noting that works as base station The light load that is born or it is non-loaded when, energy consumption still can reach the 90% of its energy consumption peak value.This group number is shown pair Base station is operated will be as the applicable approach of a reduction energy consumption.

In order to meet the design principle that can ensure service quality (Quality of Service, QoS) at any time, Operator would generally affix one's name to many base stations to eliminate communication blind district inside a panel region.Although this changed with increasing number of base stations It takes the means that system performance is promoted highly effective, but the base station due to there are a large amount of low utilization rates, consumes a large amount of energy. In conjunction with the tidal effect of communication service, the low utilization rate base station in closing part in section of low business hours and region may be used, and The mode that base station provides covering is not turned off by remaining, base station energy consumption is greatly reduced.Provide that communication cell can in 3GPP Rel-9 According to statistical parameters such as flow load, state durations, to determine whether cell closes by related algorithm.According to judgement side Formula, the method that cell is closed can be divided into two major classes, and one kind is only to carry out closing judgement by the signaling exchange between neighbouring base station, As distributed method for closing；Another kind of is to select a group head to carry out unified operation between base station, as centralized closing side Method.Distributed method for closing is more flexible, can be adjusted according to local region information and close decision.Centralized method for closing needs Whole cell informations are obtained, time decision is longer.

《Distributed Inter-BS Cooperation Aided Energy Efficient Load Balancing for Cellular Networks》、《Traffic-and-Interference Aware Base Station Switching for Green Cellular Networks》In equal pertinent literatures, to the energy resources of cellular communications networks Management has more deep introduction and research.Although previous literature also adds while considering communication service tidal regime Different measurement standards lacks the user distribution characteristic in communication cell deep more reasonably to carry out closing judgement The understanding entered and consideration, this cell for causing part utilization rate low fail closing, so that the energy saving effect that cell is closed Fruit is affected.Therefore, the present invention, which is directed to, is based on orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) the energy resources management of LTE-A cellular network communication cell have made intensive studies, analyze Previous literature proposes that the cell of method closes judgment condition, and selection receives the algorithm of shifting flows base station, and combines small A kind of user distribution characteristic in area, it is proposed that new cell method for closing.

Bibliography

1、Distributed Inter-BS Cooperation Aided Energy Efficient Load Balancing for Cellular Networks,IEEE Transactions on Wireless Communications, (Volume:12,Issue:11).

2、Traffic-and-Interference Aware Base Station Switching for Green Cellular Networks,IEEE18th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks(CAMAD),2013.

Invention content

The main object of the present invention is, non-in its in the communication network disposed to cope with peak period portfolio In the case of causing vast resources waste when peak period, for the scene of user's random distribution in a cellular communication network, To promote communication system energy efficiency as target, builds the LTE-A downlink communication environment based on OFDM and complete for low utilization The power-save operation of rate cell.It solves the problems, such as to expend spare resources in non-peak period communication network, and by combining user Location information belongs to the communication quality for the transfer user for being turned off cell originally to reduce algorithm complexity and guarantee.

For the distributed user location aware cell method for closing of LTE-A cellular network, feature is：Pass through combination The number of users information of center cell and its neighboring community and cell flow information, joint determine that the poor efficiency for being suitble to close is small Area dynamically reduces the search range of transfer user's optimum reception set according to center cell user location, is improved to reach System capacity utilization rate and the purpose for reducing algorithm complexity.The present invention realizes according to the following steps successively：

Distributed user location aware cell method for closing for LTE-A cellular network, it is characterised in that including as follows Step：

Step 1：System initialization；

The communication network model in the present invention is set as LTE-A multiple cell self organizing network models, communication environment is set as LTE-A downstream communications links based on OFDM technology；Each communication cell is divided into three sectors, and using with 120 ° of arguments Directional aerial, and 25 different resource blocks are distributed in each sector；All users random distribution in 19 communication cells, and Assuming that holding position is constant；All users always with its belonging to base station with not variable Rate carry out data exchange；Base station is directed to The transmission power of different user is assigned in the frequency resource block used in it, and according to its selected message transmission rate into Row adjustment；

Step 2：For single user UE_i, receive Signal to Interference plus Noise Ratio Signal to Interference Plus Noise Ratio, SINR are：

Wherein P_i,recievedPower is received for the useful signal that user terminal receives；I_i,intraFor co-channel interference in cell； I_i,interFor minizone co-channel interference；P_NFor additive white Gaussian noise, since this method uses OFDM technology, communication is small Co-channel interference is not present in area；

Step 3：According to known SINR, UE_iSpectrum efficiency Spectral Efficiency, SE can be expressed as：

Wherein 0≤ξ≤1 is the decay factor for including active loss；γ_minIt is the minimum that can be used for calculating spectrum efficiency SINR；γ_maxIt is the maximum SINR that can be used for calculating spectrum efficiency；ψ_maxIt is available maximum spectral efficiency；

Step 4：According to known SE, UE_iOccupied resource block Resource Blocks, RB number is represented by：

Wherein R_iIt is UE_iRequested message transmission rate；W_RBIt is the bandwidth shared by a resource block；Operator [x] indicates Rounding operation is carried out to x；

Step 5：Obtaining base station BS_jAfter RB numbers shared by all users, BS_jLoad factor Load Factor, LF It is represented by：

Wherein β_i,jIt is slaves to BS_jUE_iRequested RB numbers；RB_totalIt is BS_jAll RB numbers possessed；

Step 6：Consideration is made decisions successively to each base station according to the closing sequence pre-established：

Step 6.1：Judge BS_jWhen in leading decision, if enter judgement for the first time and consider；

Step 6.2：If it is, being not turned off the number of users and BS of cell according to surrounding_jFlow load consider that it is No suitable closing；

Step 6.3：If it is not, then according only to BS_jFlow load consider it if appropriate for closing；

Step 7：Considering to close cell BS according to user_jInterior distribution situation, exclude receive transfer user's possibility compared with Low neighboring community, so that it is determined that receiving BS_jThe reception base station range of user；

Step 8：According to the very big algorithm of minimization from receiving in base station range, the case where keeping user's original transmission rate Under, it selects one group of optimal set to receive transfer user and closes BS_jIf gathered without available reception, BS_jThen keep it turning on；

Step 9：Until repeating step 2 to base station Close All of the step 8 until all suitable closings.

Description of the drawings

Fig. 1 LTE-A self-organizing cellular network models；

Fig. 2 co-channel interference situation schematic diagrams；

Fig. 3 number of users is combined with flow information considers flow chart；

Algorithm complexities of the Fig. 4 based on user location reduces concept map；

Fig. 5 user's random distribution schematic diagram；

Fig. 6 dynamic disturbance effects compare figure；

Fig. 7 joints consider that effect compares figure；

Fig. 8 the method for the present invention complexity minimizing effects compare figure；

Fig. 9 differences consider that scheme works compare figure；

The base stations Figure 10 close number and contact figure with system total energy consumption；

Figure 11 flow diagrams of the present invention.

Specific implementation mode

Below in conjunction with Figure of description, the specific implementation mode of the present invention is illustrated：

Refering to Figure 1, the LTE-A self-organizing cellular network concept maps used for the present invention.Arbitrary base station only and its Adjacent base station carries out the communication interaction of user information and flow information.Although being exchanged without information above between non-conterminous base station, But it can be influenced each other by common adjacent base station.

It please refers to shown in Fig. 2, is co-channel interference situation schematic diagram.The figure illustrates only in same time, use With the cell of source base station same resource block co-channel interference can be generated to the user of source base station service.

It please refers to shown in Fig. 3, combines with flow information for number of users and consider flow chart.The figure explains number of users letter The cooperation flow of breath and flow information.

It please refers to shown in Fig. 4, concept map is reduced for the algorithm complexity based on user location.Figure illustration basis The location determination of intra-cell users receives the idea that set shrinks range.

It please refers to shown in Fig. 5, is user's random distribution schematic diagram.In figureIndicate base station location,Indicate user location

Step (1), for 19 Cellular Ad hoc networks models, set its station spacing asRice.And based on for The considerations of frequency resource manages, each communication cell is divided into three sectors, is all made of the directional aerial with 120 ° of arguments.Often 25 different resource blocks are distributed in a sector, and the bandwidth of each resource block is 180kHz.All users are in 19 communication cells Random distribution, and assume holding position it is constant, and always with its belonging to base station with not variable Rate carry out data exchange.To save Frequency resource, sets each user and is only allowed and account for there are one resource block, thus base station for user transmission power by basis The selected message transmission rate of the user is adjusted.Base station maximum transmission power setting is 43dBm, and setting is distributed to often A downlink data transmission channel, i.e., the minimum emissive power and maximum transmission power of each user are respectively 15dBm and 30dBm. The distribution power given tacit consent to each user is set as minimum emissive power.

Step (2), for single user UE_i, receiving SINR is：

Wherein P_i,recievedPower, I are received for the useful signal that user terminal receives_i,intraFor co-channel interference in cell, I_i,interFor minizone co-channel interference, P_NFor the additive white Gaussian noise that noise density is -174dBm/Hz.Since this method uses OFDM technology, therefore co-channel interference, i.e. I are not present in communication cell_i,intra=0, and minizone co-channel interference is then in phase With in the time, with UE_iUse same resource block and all user ∑ UE influential on its_i'≠iOwn base station for UE_iWork( Rate is superimposed, i.e. ∑ P_{i'≠i,recieved}.P in order to obtain_i,recieved, present invention employs the non-visual link (Non- of WINNER+ Line-Of-Sight, NLOS) city macrocell (Urban Macrocell, UMa) channel model：

PL=(44.9-6.55log₁₀(h_BS))log₁₀(d)+5.83log₁₀(h_BS)+14.78+34.97log₁₀(f_c)

Wherein base station height h_BS25 meters are set as, carrier frequency f_cBe set as 2GHz, d be base station to the geometry between user away from From.In conjunction with above formula and other relevant parameters, then P_i,recievedIt can be represented as：

dBm(P_i,recieved)=P_i+AG-PL-PeL-NF

Wherein P_iTo distribute to UE_iPower, AG is antenna gain, and PeL is penetration loss, and NF is the noise system of user terminal Number, dBm (x) represent the dBm forms of x.

Step (3), according to known SINR, UE_iSpectrum efficiency SE can be expressed as：

Wherein 0≤ξ≤1 is the decay factor for including active loss, γ_minIt is the minimum that can be used for calculating spectrum efficiency SINR, γ_maxIt is the maximum SINR, ψ that can be used for calculating spectrum efficiency_maxIt is available maximum spectral efficiency；

Step (4), according to known SE, UE_iOccupied resource block RB is represented by：

Wherein R_iIt is UE_iRequested message transmission rate；W_RBIt is the bandwidth shared by a resource block；Operator [x] indicates Rounding operation is carried out to x；According to the setting in step (1), β_iIt is necessarily equal to 1, therefore in β_iWhen ≠ 1, need to its P_iAllowing SINR, SE are adjusted and regained in range and carry out number of resource blocks purpose calculating again.

Step (5), in β_iAnd P_iAfter all no longer needing adjustment, BS_jLoad factor LF i.e. be represented by：

Wherein β_i,jIt is slaves to BS_jUE_iRequested RB numbers；RB_totalIt is BS_jAll RB numbers possessed.

Step (6), after the flow information for generating all base stations, according to the closing sequence pre-established to each base station Consideration is made decisions successively：

Step (6.1), judges BS_jWhen in leading decision, if enter judgement for the first time and consider.

Step (6.2) enters judgement if it is first time and considers, then first counts the number of users of peripheral cell, and to it It averages, if BS_jNumber of users be less than the average value, and BS_jFlow load be less than the closing threshold value of setting, then it is accurate The standby reception collection of base stations for starting search and capable of receiving its whole shifting flows and being lost without any QoS.If BS_jUse Amount mesh is not less than peripheral cell user's average value, and BS_jFlow load be less than setting closing threshold value, then first consider close Other base stations.If BS_jFlow load not less than setting closing threshold value, then do not consider further that close the base station.

Step (6.3) enters judgement if not first time and considers, then according only to BS_jFlow load whether consider it It is suitble to close, even BS_jFlow load be less than setting closing threshold value, then prepare start search can receive its all shift Flow and the reception collection of base stations lost without any QoS.

Step (7) calculates BS_jNumber of users in interior neighboring community corresponding region, if number of users in a certain region It is zero, then excludes the reception set containing the cell corresponding to the region from search range, reception set is attempted in reduction Number can be represented as：

Wherein T_tranFor the reception number of sets obtained in the way of full search, T_locaTo exclude corresponding region number of users The reception number of sets obtained after the cell for being zero, RS_n,lSet, n are received for first containing n cell_maxFor all receptions The most number of cells contained in set, l_totalFor the reception set sum containing n cell, n_excFor BS_jSurrounding is excluded Number of cells,

Step (8), according to the very big algorithm of minimization from reception base station range, the case where not losing user communication quality Under, it selects one group of optimal set to receive transfer user and closes BS_jIf gathered without available reception, BS_jThen keep it turning on：

Step (8.1) calculates RS_n,lIn each base station estimate load factor Estimated Load Factor, ELF：

ρ_j',elf=ρ_j'+ρ_j→j'≤ρ_max(j'≠j)

Wherein ρ_j'For BS_jAdjacent base station BS_j'The load of itself, ρ_j→j'For BS_jIt is transferred to BS_j'Load, ρ_maxFor base station Maximum acceptable load threshold.If ρ_j ^'+ρ_j→j'＞ ρ_max, then judge that the reception set is unavailable.

If the reception set is available, sums to the load of estimating of all base stations in gathering, all turned with obtaining receiving Divert from one use to another whole flow loads of the set behind family：

Step (8.2) is maximized the load flow of all reception set with same base number, and records this and connect It collects and closes：

Wherein l_maxFor the sum of the reception set containing n cell.It is as far as possible to take the purpose of load flow maximum value The ability to accept for receiving base station is made full use of, and improves the closing possibility of other base stations for possessing relatively low flow load, because After receiving transfer user, transfer user may cause the reception base station that cannot close.

Step (8.3), in order to make transfer user be linked into base station few as possible, therefore to being obtained in step (8.2) All load flow maximum values reception set for being minimized, and possessing the minimum load flow be optimal reception collection It closes：

Step (9), until repeating step (2) to base station Close All of the step (8) until all suitable closings.

Comparing figure based on Fig. 6 dynamic disturbance effects can represent：Included in the present invention dynamic disturbance consider, i.e., with The way that update transmission power and interference information are closed in each base station, the section that cell method for closing is brought can be significantly increased It can effect.Data are emulated in figure every time to be obtained by 100 different user's random distribution scenes.In figureIt indicates not Consider the method for closing (non dynamic interference, non_di) of dynamic disturbance,It indicates to consider that dynamic is dry The method for closing (dynamic interference, di) disturbed.

Combined based on Fig. 7 and considers that effect compares figure and can represent：The number of users limitation for including in the present invention and flow Information consolidation considers that the number for closing cell can be increased to a certain extent.And it is of note that for fixed use Family quantity threshold, obtained energy-saving effect is different, and it is lower to show number of users threshold value, and it is more that number is closed in base station General trend.However too low threshold value setting also results in the unstable of energy-saving effect, and fixed threshold value lack for The adaptability of different distributions situation.And the consecutive mean number of users method for limiting proposed in the present invention then can be small according to periphery The number of users in area dynamically adjusts threshold value and obtains certain energy saving profit, that is, increases the number for closing base station.In figureIndicate di method for closing,It indicates to consider the di method for closing that number of users limitation and threshold value are 15 (dynamic interference number 15, di_num_15),It indicates to consider number of users limitation and threshold value For 17 di method for closing (dynamic interference number 17, di_num_17),It indicates to consider to use The di method for closing (dynamic interference number 19, di_num_19) that amount mesh limits and threshold value is 19,It indicates to consider di method for closing (the dynamic interference number that number of users limitation and threshold value are 21 21, di_num_21),It indicates to consider the di method for closing (dynamic that consecutive mean number of users limits Interference number average, di_num_average).

Comparing figure based on Fig. 8 the method for the present invention complexity minimizing effects can represent：Include in the present invention based on pass The algorithm complexity reduction method for closing intra-cell users position does not influence the energy-saving effect of system substantially.In figure Indicate di method for closing,Expression considers the di method for closing (dynamic of the reduction algorithm complexity of user location Interference predict, di_predict).

Consider that scheme works compare figure and can represent based on Fig. 9 differences：Dynamic disturbance, number of users, user location and The joint of flow information considers can be while reducing algorithm complexity, the number of cell closing in lifting system.From figure As can be seen that in di_num_average methods and di_pre_num_aver methods, the situation that number of base stations is more than 5 is closed Reach 85% or so, and di methods and di_predict methods are then maintained at 70% or so.Although di_num_average The considerations of in method comprising algorithm complexity is reduced, but do not significantly affect the number for closing cell.In figureTable Show di method for closing,Indicate di_predict method for closing,Indicate di_num_average method for closing,Expression considers di method for closing (the dynamic interference of number of users limitation and user location Predict and number average, di_pre_num_aver).

Contacting figure with system total energy consumption based on the base stations Figure 10 closing number can represent：As cell base station closes number Increase, system total energy consumption also declines therewith, further demonstrates the validity of cell method for closing.In figureIt indicates System energy consumption under different consideration methods,Indicate that number is closed in the base station under different consideration methods.Di_ in figure Predict is abbreviated as di_p, and di_num_average is abbreviated as di_n, and di_pre_num_aver is abbreviated as di_p_n.

Claims (1)

1. the distributed user location aware cell method for closing for LTE-A cellular network, it is characterised in that including walking as follows Suddenly：

Step 1：System initialization；

Communication network model is LTE-A multiple cell self organizing network models, and communication environment is set as the LTE-A based on OFDM technology Downstream communications link；Each communication cell is divided into three sectors, and using the directional aerial with 120 ° of arguments, and each fan Area distributes 25 different resource blocks；All users random distribution in 19 communication cells, and assume that holding position is constant；Institute It is useful per family always with its belonging to base station with not variable Rate carry out data exchange；Base station is directed to the transmission power quilt of different user It is assigned in the frequency resource block used in it, and is adjusted according to its selected message transmission rate；

Step 2：For single user UE_i, receive Signal to Interference plus Noise Ratio Signal to Interference plus Noise Ratio, SINR are：

Wherein, UE_iFor i-th of user terminal, P_i,recievedPower is received for the useful signal that user terminal receives；I_i,intraIt is small Co-channel interference in area；I_i,interFor minizone co-channel interference；P_NFor additive white Gaussian noise, since this method uses OFDM skills Art, therefore co-channel interference is not present in communication cell；

Step 3：According to known SINR, UE_iSpectrum efficiency Spectral Efficiency, SE can be expressed as：

Wherein 0≤ξ≤1 is the decay factor for including active loss；γ_minIt is the minimum SINR that can be used for calculating spectrum efficiency； γ_maxIt is the maximum SINR that can be used for calculating spectrum efficiency；ψ_maxIt is available maximum spectral efficiency；

Step 4：According to known SE, UE_iOccupied resource block Resource Blocks, RB number is represented by：

Wherein R_iIt is UE_iRequested message transmission rate；W_RBIt is the bandwidth shared by a resource block；Operator [x] indicate to x into Row rounding operation；

Step 5：Obtaining base station BS_jAfter RB numbers shared by all users, BS_jLoad factor Load Factor, LF can table It is shown as：

Wherein β_i,jIt is slaves to BS_jUE_iRequested RB numbers；RB_totalIt is BS_jAll RB numbers possessed, BS_jFor jth A base station；

Step 6：Consideration is made decisions successively to each base station according to the closing sequence pre-established：

Step 6.1：Judge BS_jWhen in leading decision, if enter judgement for the first time and consider；

Step 6.2：If it is, being not turned off the number of users and BS of cell according to surrounding_jFlow load consider its if appropriate for It closes；

Step 6.3：If it is not, then according only to BS_jFlow load consider it if appropriate for closing；

Step 7：Considering to close cell BS according to user_jInterior distribution situation excludes to receive the transfer lower phase of user's possibility Adjacent cell, so that it is determined that receiving BS_jThe reception base station range of user；

Step 8：According to the very big algorithm of minimization from reception base station range, in the case of holding user original transmission rate, It selects one group of optimal set to receive transfer user and closes BS_jIf gathered without available reception, BS_jIt then keeps it turning on, has Body includes the following steps：

Step (8.1) calculates RS_n,lIn each base station estimate load factor Estimated Load Factor, ELF ρ_j',elf：

ρ_j',elf=ρ_j'+ρ_j→j'≤ρ_max(j'≠j)

Wherein, RS_n,lIt indicates to receive set, ρ first that possesses n base station_j'For BS_jAdjacent base station BS_j'The load of itself, ρ_j→j' For BS_jIt is transferred to BS_j'Load, ρ_maxFor the maximum acceptable load threshold of base station, if ρ_j'+ρ_j→j'>ρ_max, then judge that this connects It is unavailable to collect conjunction,

If the reception set is available, sum to the load of estimating of all base stations in gathering, is used with obtaining receiving all transfers Whole flow load S of the set behind family_n,l：

Step (8.2) is maximized the load flow of all reception set with same base number, and records the reception collection It closes：

Wherein, l_maxFor the sum of the reception set containing n cell, it is to fill as far as possible to take the purpose of load flow maximum value Divide the ability to accept using reception base station, and improve the closing possibility of other base stations for possessing relatively low flow load, because connecing After receiving transfer user, transfer user may cause the reception base station that cannot close；

Step (8.3), in order to make transfer user be linked into base station few as possible, therefore the institute to being obtained in step (8.2) The reception set that some load flow maximum values are minimized, and possess the minimum load flow is optimal reception set：

Step 9：Until repeating step 2 to base station Close All of the step 8 until all suitable closings.