CN102612046A - Energy-saving dynamic frequency spectrum planning method in femtocell network - Google Patents

Abstract

The invention relates to an energy-saving dynamic frequency spectrum planning method in a femtocell network and provides an energy-saving dynamic frequency plan based on soft frequency reuse in a bilayer femtocell network, wherein an energy-consumption model of a downlink of a three-dimensional space femtocell bilayer network is established. According to the method disclosed by the invention, a soft frequency reuse scheme is adopted, interferences to macro cell users in a cell edge area are reduced, and the interruption rate of the edge users is reduced. Frequencies distributed to macro cell users and femtocell users in an internal area are orthogonal mutually, cross-layer interferences between a macro cell network layer and a femtocell network layer are avoided, the user distribution and business traffic distribution of the internal area and an external area of the macro cell are fully considered on the premise of guaranteeing QoS (Quality of Service) requirements of the users, the frequency spectra distributed to the macro cell users and the femtocell users are dynamically adjusted, the frequency spectrum utilization rate is increased, and thus, the energy utilization rate of the entire network is increased.

Description

Energy-conservation dynamic spectrum planing method in the femtocell network

Technical field

The present invention relates to the mobile communication technology field; Special; The present invention is used in next generation mobile communication system (LTE/LTE-Advanced) Femto cell (Femtocell) double-layer network based on soft-frequency reuse (Soft frequency reuse, energy-conservation frequency planning method SFR).

Background technology

At present; 3-G (Generation Three mobile communication system) has obtained commercial widely; Simultaneously; The 9th version (Release-9) of the evolution technology of UMTS (UMTS)---LTE standard also formulated in the end of the year 2010 and accomplished, and the standard formulation of the 4th third-generation mobile communication system (Release-11) starts, and is placed high hopes by the leading LTE-Advanced technology of formulating of 3GPP.

Along with development of wireless communication devices, for the LTE system, the access way of the OFDMA of the uniqueness that it adopts makes and does not disturb mutually between the user in this sub-district, then receives the more intense interference that comes from other sub-districts for the user of cell edge.In order to solve the problem of LTE owing to the Cell Edge User serious interference that adopts OFDMA to cause; The interference coordination of OFDMA/avoid technology has been proposed; Wherein the soft-frequency reuse scheme is more flexible for the distribution of frequency; Effect having fully played interference coordination/avoid has also better adapted to the trend of professional variation sub-district the in simultaneously.

Along with the wireless communication system frequency of utilization is increasingly high, the decay meeting of signal is more serious, the signal strength signal intensity that causes owing to reasons such as blocking of building simultaneously and the decline of quality; Yet the user is but promoting for the demand of service quality gradually; In order to realize that better internal home network covers and network capacity expands, LTE has also introduced Femtocell (Femto cell), shows according to ASSOCIATE STATISTICS both domestic and external; The voice service in 3G epoch 70% and 90% data service occur in indoor; Better indoor covering not only can be satisfied the demand of ever-increasing service quality of user and two-forty, because Home eNodeB is disposed by the user voluntarily, can save the fixed capital input of operator simultaneously; Improve the income of operator, places such as that Home eNodeB can be deployed in is indoor, university, company, market.

Compare with common macro base station; Femto cell base station has that volume is little, transmitting power is low, user's characteristics such as installation and maintenance, plug and play voluntarily; Each big operator, equipment commercial city give Femto cell with great concern both at home and abroad at present; In areas such as North America, Singapore, femto cell base station has obtained commercial preferably.

Continuous growth along with message reference; Mobile communications network has become one of factor of main energy resource consumption; There are some researches show that Radio Access Network surpasses 80% in the energy resource consumption of mobile communications network, a large amount of deployed back sub-district lot of energy of Femto cell, the energy efficiency of increase mobile communications network; Particularly the energy efficiency of femtocell network becomes very urgent.

Yet, owing to Femto cell is disposed by the user, and open and close the uncertainty that is had, make frequency planning become a new challenge with Femto cell double-layer network.In existing research, mainly be static frequency allocation method and the frequency planning in single sub-district about the focus of the frequency planning of Femto cell, do not consider the interference coordination of minizone.Existing method is difficult to effectively reduce the interference of minizone in the double-layer network, and the energy consumption that reduces double-layer network.

Summary of the invention

The present invention is intended to fail in the Femto cell upper layer network of the fine solution problem of interference coordination between macrocell and energy consumption of existing frequency planning; Proposed a kind ofly based on the energy-conservation dynamic frequency planing method of soft-frequency reuse, this method can effectively be avoided between macrocell disturbing and reduce energy consumption.

To achieve these goals, solve the corresponding techniques problem, the invention provides a kind of based on the energy-conservation dynamic frequency programme of soft-frequency reuse:

Step 1: macro cells is divided into three sectors, and each sector is divided into two zones: interior zone and perimeter, and set up energy consumption model;

Step 2: the frequency band of authorizing in the OFDMA wireless network is divided into three parts;

Step 3: macro base station is provided with central entity, and central entity is confirmed the positional information of each portable terminal and Femto cell;

Step 4: the frequency planning of perimeter: based on soft-frequency reuse; The macrocell user of each perimeter, sector can utilize the part of authorized frequency bands; The bandwidth that the macrocell user of adjacent sectors perimeter is assigned to is mutually orthogonal, and the Femto cell user is assigned to whole authorized frequency bands;

Step 5: the frequency planning of interior zone: the macrocell user of the sector interior zone frequency (this frequency is not used by other grand users) of distributing to this perimeter, sector macrocell user both capable of using; The part (macro base station is with the signal on this frequency of lower power emission) of all right multiplexing residue frequency band; Proportion is ρ; And another part of the multiplexing residue frequency band of the Femto cell of interior zone, proportion is 1-ρ.

In step 1, set up the energy consumption model of double-layer network: the macro base station total power consumption mainly comprises two parts, and a part is quiescent dissipation and dynamic power consumption, and the average transmit power of establishing macro base station is P _M, its total power consumption is P _Mtotal, then:

P _Mtotal=N _SecN _APa _MP _MWith P _CM

Wherein

Represent the sector number in each macrocell, N _APThe number of representing each sector intermediate power amplifier, a _MBe proportionality coefficient constant, P _CMFor with average transmit power P _MSeparate constant, Home eNodeB total power consumption are P _Ftotal=b _FP _F+ P _CFSo the power consumption of whole system consumes P in the sub-district _TotalFor: P _Total=P _Mtotal+ N _fP _Ftotal, N wherein _fNumber for Femto cell in the sub-district.

In step 2; Portable terminal in the sub-district is measured the Reference Signal Received Power (RSRP) from the sub-district, and feeds back to the affiliated subdistrict base station, and the central entity of cell base station compares according to the Reference Signal Received Power and the thresholding δ of portable terminal feedback; If RSRP＞δ; Then be divided into inner portable terminal to this portable terminal, if this portable terminal is the Femto cell user, then the Femto cell at this portable terminal place divides inner Femto cell into; Otherwise this portable terminal is divided into the external moving terminal, and the Femto cell at portable terminal place divides outside Femto cell into.

In step 5; Inner macrocell user reports relevant information with the macro base station of inner Femto cell user to the sub-district, place; This information comprises user business type and user type (macrocell user; Or Femto cell user), all information that report of central entity statistics are confirmed proportionality coefficient ρ according to following formula

$\mathrm{\ρ}=\arg \underset{0\≤\mathrm{\ρ}\≤1}{\max }\frac{T}{P_{\mathrm{total}}}$

$T=\frac{2}{3}\mathrm{\ρ}{T}_{m,\mathrm{In}}+\frac{2}{3}(1-\mathrm{\ρ})N_{f,\mathrm{In}}{T}_{f,\mathrm{In}}+\frac{1}{3}{T}_{m,\mathrm{Out}}+N_{f,\mathrm{Out}}{T}_{f,\mathrm{Out}},$ T wherein _{M, in}And T _{F, in}Expression interior zone macrocell user and Femto cell user's unit spectrum averaging throughput, perimeter macrocell user and Femto cell user's unit spectrum averaging throughput is used T _{M, out}And T _{F, out}Represent, and satisfy the QoS demand of macrocell network layer and Femto cell layer.

The QoS of defmacro subzone network layer and Femto cell layer in the step 5 promptly guarantees user's in user's average throughput and the Femto cell in the inner macrocell network minimum average throughput, and parameter is η (0＜η＜0.5);

$\min \{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}},\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}\≥\mathrm{\η}\{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}}+\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}$

Can find out that from above technical scheme method of the present invention has reduced the interference that cell edge region macrocell user receives, reduce the interruption rate of edge customer.The frequency that the macrocell user of interior zone and Femto cell user are assigned to is mutually orthogonal; Avoided the bigger layer of striding between macrocell network layer and the femtocell network layer to disturb; Under the situation that guarantees user QoS demand, take into full account interior zone and the perimeter user distribution and the service traffics distribution of macrocell, dynamically adjust the frequency spectrum that macrocell user and Femto cell user are assigned to; Maximize the availability of frequency spectrum, thereby improved the capacity usage ratio of whole network.

Through accompanying drawing and specific embodiment technical scheme of the present invention is further set forth below.

Description of drawings

In order to set forth embodiments of the invention and existing technical scheme more clearly; Below the explanation accompanying drawing of using in technical scheme explanation accompanying drawing of the present invention and the description of the Prior Art is done simple introduction; Conspicuous; Under the prerequisite of not paying creative work, those of ordinary skills can obtain other accompanying drawing through this accompanying drawing.

Shown in Figure 1 is based on the sub-band planning chart of soft-frequency reuse in the embodiment of the invention;

Shown in Figure 2 is the subband allocation flow chart of a Femto cell in the embodiment of the invention;

Embodiment

Clearer for what technical scheme advantage of the present invention was described, further be discussed in more detail below in conjunction with the accompanying drawing specific embodiments of the invention, obvious described embodiment is part embodiment of the present invention, rather than whole embodiment.According to embodiments of the invention, those of ordinary skill in the art can realize every other embodiment of the present invention on without the basis of creative work, all belong to protection scope of the present invention.

In the following description, the technology that has nothing to do with the present invention is only done concise and to the point technical descriptioon or directly skip over.

Main thought of the present invention is, adopts soft-frequency reuse between macrocell, avoids the interference of minizone.After Femto cell is disposed; At first portable terminal is to the macro base station transmitted reference signal; Macro base station confirms that according to reference signal strength portable terminal is positioned at positional information, meanwhile adds up inside and outside zone macrocell user and Femto cell user's information such as business; Take into full account interior zone and the perimeter user distribution and the service traffics distribution of macrocell; Dynamically adjust the frequency spectrum that macrocell user and Femto cell user are assigned to, maximize the capacity usage ratio of system, guarantee user's QoS simultaneously.

The term that hereinafter is quoted " macro base station " comprises but does not belong to eNodeB, base station, evolved base station etc.The term that hereinafter is quoted " femto cell base station " then is to comprise but do not belong to Home eNodeB, base station from home, femtocell access point etc.

Shown in Figure 1 is sub-band planning chart based on soft-frequency reuse; It comprises the division of three sub-districts, nine sectors and 101 authorized frequency bands; Special, each sector is divided into interior zone and perimeter, confirms the positional information of portable terminal according to the intensity of the reference signal of portable terminal.

Fig. 2 is the subband allocation flow chart of a Femto cell of the embodiment of the invention, is example with one of them sector, specifically comprises:

Step 201: macro cells is divided into three sectors, and each sector is divided into two zones: interior zone and perimeter, and set up energy consumption model.

The energy consumption model of the double-layer network of setting up in this step is: the macro base station total power consumption mainly comprises two parts, and a part is quiescent dissipation and dynamic power consumption, and the average transmit power of establishing macro base station is P _M, its total power consumption is P _Mtotal, then:

P _Mtotal＝N _secN _APa _MP _M+P _CM

N wherein _SecRepresent the sector number in each macrocell, N _APThe number of representing each sector intermediate power amplifier, a _MBe proportionality coefficient constant, P _CMFor with average transmit power P _MSeparate constant, Home eNodeB total power consumption are P _Ftotal=b _FP _F+ P _CFSo the power consumption of whole system consumes P in the sub-district _TotalFor: P _Total=P _Mtotal+ N _fP _Ftotal, N wherein _fNumber for Femto cell in the sub-district.

Step 202: the frequency band of authorizing in the OFDMA wireless network is divided into three parts.

Step 203: macro base station is provided with central entity, and central entity is confirmed the positional information of each portable terminal and Femto cell.

Portable terminal in this step in the sub-district is measured the Reference Signal Received Power (RSRP) from the sub-district; And feed back to the affiliated subdistrict base station; The central entity of cell base station compares according to the Reference Signal Received Power and the thresholding δ of portable terminal feedback, if RSRP＞δ then is divided into inner portable terminal to this portable terminal; If this portable terminal is the Femto cell user; Then the Femto cell at this portable terminal place divides inner Femto cell into, otherwise this portable terminal is divided into the external moving terminal, and the Femto cell at portable terminal place divides outside Femto cell into.

Step 204: the frequency planning of perimeter: based on soft-frequency reuse; The macrocell user of each perimeter, sector can utilize the part of authorized frequency bands; The bandwidth that the macrocell user of adjacent sectors perimeter is assigned to is mutually orthogonal, and the Femto cell user is assigned to whole authorized frequency bands.

Step 205A: inner macrocell user reports relevant information with the macro base station of inner Femto cell user to the sub-district, place; This information comprises user business type and user type (macrocell user; Or Femto cell user); All information that report of central entity statistics are confirmed proportionality coefficient ρ according to following formula

$\mathrm{\ρ}=\arg \underset{0\≤\mathrm{\ρ}\≤1}{\max }\frac{T}{P_{\mathrm{total}}}$

$T=\frac{2}{3}\mathrm{\ρ}{T}_{m,\mathrm{In}}+\frac{2}{3}(1-\mathrm{\ρ})N_{f,\mathrm{In}}{T}_{f,\mathrm{In}}+\frac{1}{3}{T}_{m,\mathrm{Out}}+N_{f,\mathrm{Out}}{T}_{f,\mathrm{Out}},$ T wherein _{M, in}And T _{F, in}Expression interior zone macrocell user and Femto cell user's unit spectrum averaging throughput, perimeter macrocell user and Femto cell user's unit spectrum averaging throughput is used T _{M, out}And T _{F, out}Represent, and satisfy the QoS demand of macrocell network layer and Femto cell layer.

The QoS of defmacro subzone network layer and Femto cell layer among the step 205A promptly guarantees user's in user's average throughput and the Femto cell in the inner macrocell network minimum average throughput, and parameter is η (0＜η＜0.5).

$\min \{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}},\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}\≥\mathrm{\η}\{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}}+\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}$

Step 205B: the frequency planning of interior zone: the macrocell user of the sector interior zone frequency (this frequency is not used by other grand users) of distributing to this perimeter, sector macrocell user both capable of using; The part (macro base station is with the signal on this frequency of lower power emission) of all right multiplexing residue frequency band; Proportion is ρ; And another part of the multiplexing residue frequency band of the Femto cell of interior zone, proportion is 1-ρ.

Claims (5)

1. energy-conservation dynamic spectrum planing method in the femtocell network is characterized in that may further comprise the steps:

Step 1: macro cells is divided into three sectors, and each sector is divided into two zones: interior zone and perimeter, and set up energy consumption model;

Step 2: the frequency band of authorizing in the OFDMA wireless network is divided into three parts;

Step 3: macro base station is provided with central entity, and central entity is confirmed the positional information of each portable terminal and Femto cell;

Step 4: the frequency planning of perimeter: based on soft-frequency reuse; The macrocell user of each perimeter, sector can utilize the part of authorized frequency bands; The bandwidth that the macrocell user of adjacent sectors perimeter is assigned to is mutually orthogonal, and the Femto cell user is assigned to whole authorized frequency bands;

Step 5: the frequency planning of interior zone: the macrocell user of the sector interior zone frequency (this frequency is not used by other grand users) of distributing to this perimeter, sector macrocell user both capable of using; The part (macro base station is with the signal on this frequency of lower power emission) of all right multiplexing residue frequency band; Proportion is ρ; And another part of the multiplexing residue frequency band of the Femto cell of interior zone, proportion is 1-ρ.

2. according to claim 1 based on the energy-conservation dynamic frequency planing method of soft-frequency reuse, it is characterized in that:

In the said step 1, set up the energy consumption model of double-layer network: the macro base station total power consumption mainly comprises two parts, and a part is quiescent dissipation and dynamic power consumption, and the average transmit power of establishing macro base station is P _M, its total power consumption is P _Mtotal, then:

P _Mtotal＝N _secN _APa _MP _M+P _CM

N wherein _SecRepresent the sector number in each macrocell, N _APThe number of representing each sector intermediate power amplifier, a _MBe proportionality coefficient constant, P _CMFor with average transmit power P _MSeparate constant, Home eNodeB total power consumption are P _Ftotal=b _FP _F+ P _CFSo the power consumption of whole system consumes P in the sub-district _TotalFor: P _Total=P _Mtotal+ N _fP _Ftotal, N wherein _fNumber for Femto cell in the sub-district.

3. according to claim 1 based on the energy-conservation dynamic frequency planing method of soft-frequency reuse, it is characterized in that:

In the said step 3; Portable terminal in the sub-district is measured the Reference Signal Received Power (RSRP) from the sub-district, and feeds back to the affiliated subdistrict base station, and the central entity of cell base station compares according to the Reference Signal Received Power and the thresholding δ of portable terminal feedback; If RSRP＞δ; Then be divided into inner portable terminal to this portable terminal, if this portable terminal is the Femto cell user, then the Femto cell at this portable terminal place divides inner Femto cell into; Otherwise this portable terminal is divided into the external moving terminal, and the Femto cell at portable terminal place divides outside Femto cell into.

4. according to claim 1 based on the energy-conservation frequency planning method of soft-frequency reuse, it is characterized in that:

In the said step 4,, take all factors into consideration outside Femto cell and macrocell number of users, confirm that outside grand user belongs to the transmitting power of frequency based on soft-frequency reuse.

5. according to claim 1 based on the energy-conservation frequency planning method of soft-frequency reuse, it is characterized in that:

In the said step 5, inner macrocell user reports relevant information with the macro base station of inner Femto cell user to the sub-district, place, and this information comprises user business type and user type (macrocell user, or Femto cell user); All information that report of central entity statistics are confirmed proportionality coefficient ρ according to following formula

$\mathrm{\ρ}=\arg \underset{0\≤\mathrm{\ρ}\≤1}{\max }\frac{T}{P_{\mathrm{total}}}$

$T=\frac{2}{3}\mathrm{\ρ}{T}_{m,\mathrm{In}}+\frac{2}{3}(1-\mathrm{\ρ})N_{f,\mathrm{In}}{T}_{f,\mathrm{In}}+\frac{1}{3}{T}_{m,\mathrm{Out}}+N_{f,\mathrm{Out}}{T}_{f,\mathrm{Out}},$ T wherein _{M, in}And T _{F, in}Expression interior zone macrocell user and Femto cell user's unit spectrum averaging throughput, perimeter macrocell user and Femto cell user's unit spectrum averaging throughput is used T _{M, out}And T _{F, out}Represent, and satisfy the QoS demand of macrocell network layer and Femto cell layer;

In the said step 5, the QoS of central entity defmacro subzone network layer and Femto cell layer promptly guarantees user's in user's average throughput and the Femto cell in the inner macrocell network minimum average throughput, and parameter is η (0＜η＜0.5);

$\min \{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}},\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}\≥\mathrm{\η}\{\frac{\frac{2}{3}\mathrm{\γ}{T}_{m,\mathrm{in}}}{N_{c,\mathrm{in}}}+\frac{2}{3}(1-\mathrm{\γ})T_{f,\mathrm{in}}\}$

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