CN102421177A - Distributed power control method for Femtocell uplink - Google Patents

Abstract

The invention discloses a distributed power control method for a Femtocell uplink. In the method, based on a game theory, for a Femtocell and a macrocell base station, the maximum transmission power of a Femtocell user is limited so as to ensure that a preset signal to interference plus noise ratio (SINR) of a macro user of the macrocell base station is achieved for the macro user of the macrocell base station, and accordingly, the self preset SINRs of more Femtocell users are achieved for the more Femtocell users by means of game iteration. According to the invention, on the premise of guaranteeing the system capacitive properties, the power control for the Femtocell users is preformed in a game manner by regulating the upper limit of the transmission power of the Femtocell users, different SINR requirements of different Femtocell users are taken into consideration, all the Femtocell users are ensured to achieve the self preset SINRs as much as possible, and the distributed power control method disclosed by the invention has better performances compared with the conventional method.

Description

A kind of distributed power control method of Femtocell up link

Technical field

The invention belongs to wireless communication technology field, relate to femtocell Femtocell technology and game method, be a kind of distributed power control method of Femtocell up link.

Background technology

Femtocell Femtocell technology is the solution of the indoor covering of a kind of expanding mobile communication; Release according to 3G development in recent years and broadband mobile trend; It is operated in the mandate frequency range; Through broadband access, be connected to the network of operator like DSL, wire cable, optical fiber etc., its mainly act on be in the family room or small-business mechanism provide better signal to cover and service quality.The mutual interference problem is the major issue that Femtocell will solve always.Because frequency resource restriction, Femtocell and macrocell base stations are adopted when frequently disposing together, have brought the serious disturbance problem.

Game method element comprises game side, set of strategies, utility function etc.At present in the game formula Femtocell Poewr control method; More lay particular emphasis on from the utility function angle and reduce interlayer interference; And present Poewr control method more stresses the whole volumetric properties of network; The Signal to Interference plus Noise Ratio SINR that has ignored each Femtocell user requires the possibility condition of different, makes to exist more Femtocell user not reach its preset SINR value in the network.At document " Power control in two-tier Femtocell networks. " (V.Chandrasekhar, J.G.Andrews, etc.IEEE trans.Wireless Commun.; Aug.2009, vol.8, no.8; Pp.4316-4328.) method that proposes in, we are called primal algorithm (Original Algorithm), are abbreviated as the OA method; Be existing a kind of based on game theoretic Femtocell Poewr control method; But it does not limit Femtocell user's maximum transmission power, makes each user produce larger interference to grand user, and its link protection method reduces Femtocell user through reduction Femtocell user preset SINR value to be disturbed grand user; And this link protection method is accurate inadequately to the identification of larger interference; Its ways to restrain is inflexible, and it is more not reach the Femtocell user who self presets the SINR value in the network, and Femtocell user's communications effect is undesirable.

Summary of the invention

The problem that the present invention will solve is: have the mutual interference problem in the Femtocell technology; Existing Poewr control method has been ignored each Femtocell user's Signal to Interference plus Noise Ratio requirement; Reducing Femtocell user through reduction Femtocell user preset SINR value disturbs grand user; And it is more not reach the Femtocell user who self presets the SINR value in the network, and Femtocell user's communications effect is undesirable.

Technical scheme of the present invention is: a kind of distributed power control method of Femtocell up link; Based on game theory; To femtocell Fetomcell and macrocell base stations, guarantee that through the maximum transmission power that limits Fetomcell user the grand user of macrocell base stations reaches its preset Signal to Interference plus Noise Ratio SINR _h, make more Femtocell users reach self preset Signal to Interference plus Noise Ratio SINR through the game iteration on this basis _f, be specially: according to noise σ in the macrocell base stations covering marginal position grand user's in place the snr computation macrocellular ², the Signal to Interference plus Noise Ratio of establishing grand user is SINR _h, the Femtocell total number of users is M, all Fetomcell users are I to the maximum of this grand user's interference sum _Max, have

P wherein _MaxBe grand user's maximum transmission power, g _0,0Be the channel gain of grand user to macrocell base stations, then each Femtocell user is no more than the average interference value to the maximum interference that grand user produced:

If i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, g wherein _{0, i}Be the channel gain of i Femtocell user, I is then arranged to macrocell base stations _i≤I _Mean, i.e. p _ig _{0, i}≤I _Mean, The transmitting power strategy that obtains Femtocell user is p _i=[0, p _{I_max}], promptly transmitting power [0, p _{I_max}] in, each Femtocell user participates in the game iteration according to own corresponding transmitting power strategy, and the transmitting power when drawing equilibrium is carried out ul transmissions:

$p_0^{(k+1)}=\min \{\frac{p_0^{\left(k\right)}}{{\mathrm{\γ}}_0^{\left(k\right)}}{\mathrm{\Γ}}_0,p_{\max }\}$

$p_i^{(k+1)}=\min \{\frac{p_i^{\left(k\right)}}{{\mathrm{\&gamma;}}_i^{\left(k\right)}}{[{\mathrm{\&Gamma;}}_i+\ln \left(\frac{a_i{g}_{i,i}}{b_i{\mathrm{<figure-callout\; id="0"\; label="g"\; filenames="HDA0000118814280000031.png"\; state="\{\{state\}\}">g</figure-callout>}}_{0,i}}\right)]}^{+},p_{i\_\max }\},$ $\&ForAll;i>0$

In the formula

Represent the transmitting power after the k time iteration of grand user,

Represent i Femtocell user through the transmitting power after the k time iteration,

Represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user,

Represent i Femtocell user through the Signal to Interference plus Noise Ratio after the k time iteration, Γ ₀For representing the SINR of grand user preset _hValue, Γ _iBe the SINR of i Femtocell user preset _fValue, g _{I, i}Be the channel gain of i Femtocell user to corresponding Femtocell base station, a _iRepresent that i Femtocell user increases the weight of the income that is obtained after the transmitting power of oneself, b _iRepresent that i Femtocell user increases the weight of being paid a price after the transmitting power of oneself;

At the Signal to Interference plus Noise Ratio SINR that guarantees grand user _hPrerequisite under, each Femtocell user reaches self preset Signal to Interference plus Noise Ratio SINR as far as possible through the mode of participating in game _f

Whether the Femtocell user that its service is detected in each Femtocell base station reaches its preset Signal to Interference plus Noise Ratio SINR _f, and report to macro base station through IP network, macrocell base stations detects grand user and does not reach its preset Signal to Interference plus Noise Ratio SINR _h, or do not reach self preset Signal to Interference plus Noise Ratio SINR in the coverage _fThe Femtocell number of users increase, then broadcasting suppresses signal, after each Femtocell user receives the inhibition signal of macrocell base stations, upgrades the p of self _{I_max}: p _{I_max}=p _{I_max}-Δ p, Δ p are adjustment amount, and size is set according to the actual requirements, carry out the game iteration once more, obtain the transmitting power equilibrium point and carry out ul transmissions.

Further, reach its preset Signal to Interference plus Noise Ratio SINR grand user _hSituation under, do not reach self preset Signal to Interference plus Noise Ratio SINR _fFemtocell user report its current Signal to Interference plus Noise Ratio SINR through its Femtocell base station to macrocell base stations _FnWith preset Signal to Interference plus Noise Ratio SINR _fResidual quantity value Δ γ _i, macrocell base stations is notified wherein residual quantity value Δ γ _iMinimum Femtocell user increases upper limit of emission power by the adjustment amount Δ p that sets and participates in the game iteration once more, makes said residual quantity value Δ γ through the game iteration _iMore and more littler, reach himself preset Signal to Interference plus Noise Ratio SINR up to this Femtocell user _f

The present invention through adjustment Femtocell user emission power higher limit, carries out Femtocell user's power control by the mode of game under the prerequisite that guarantees the power system capacity performance, make more Femtocell user reach self preset SINR _fValue.The present invention has considered different Femtocell users' different Signal to Interference plus Noise Ratio requirements, at first controls the maximum I to grand user's interference sum _Max, guarantee that grand user reaches its preset Signal to Interference plus Noise Ratio SINR _h, the mode by game makes each Femtocell user increase its transmitting power then, reaches himself preset Signal to Interference plus Noise Ratio SINR as far as possible _fCompared with prior art, the present invention makes more Femtocell user reach self preset SINR value under the prerequisite that guarantees the power system capacity performance, and like Fig. 3 and shown in Figure 4, the inventive method is compared existing method and had more performance.

Description of drawings

Fig. 1 is the overall flow figure of the inventive method.

Fig. 2 is macro base station and Femtocell access point FAP (Femtocell Access Point) and user distribution sketch map separately thereof.

Fig. 3 is guaranteeing under the grand user performance prerequisite Femtocell user SINR performance comparison diagram of the inventive method and existing method OA.

Fig. 4 be the inventive method and existing method in use, Femtocell user does not reach the comparison diagram of preset Signal to Interference plus Noise Ratio percentage performance.

Embodiment

Below in conjunction with accompanying drawing technical scheme of the present invention is done further detailed description:

The inventive method to femtocell Fetomcell and macrocell base stations, guarantees that through the maximum transmission power that limits Fetomcell user the grand user of macrocell base stations reaches its preset Signal to Interference plus Noise Ratio SINR based on game theory _h, make more Femtocell users reach self preset Signal to Interference plus Noise Ratio SINR through the game iteration on this basis _fAs shown in Figure 1, the signal to noise ratio (SNR:Signal to Noise Ratio) of establishing the macrocellular covering marginal position grand user in place should reach 20dB, can calculate the noise σ in the honeycomb thus ²If grand user's Signal to Interference plus Noise Ratio SINR _h=10dB, the Femtocell total number of users is M, all Fetomcell users are I to the maximum of this grand user's interference sum _Max, disturbing when being higher than this value, this grand user's Signal to Interference plus Noise Ratio can be lower than 10dB, promptly

Have

P wherein _MaxBe grand user's maximum transmission power, g _0,0Be the channel gain of grand user to macrocell base stations.Consider fairness, each Femtocell user can not surpass the average interference value to the maximum interference that grand user produced:

If i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, p wherein _iBe g _{0, i}Be i Femtocell user's transmitting power, i Femtocell user arrives the channel gain of macrocell base stations, and I is then arranged _i≤I _Mean, i.e. p _ig _{0, i}≤I _Mean,

Guarantee that under grand user's the SINR situation, Femtocell user's transmitting power strategy is p _i=[0, p _{I_max}], promptly transmitting power [0, p _{I_max}] in, each Femtocell user participates in the game iteration according to own corresponding transmitting power strategy, and the transmitting power when drawing equilibrium is carried out ul transmissions:

$p_0^{(k+1)}=\min \{\frac{p_0^{\left(k\right)}}{{\mathrm{\&gamma;}}_0^{\left(k\right)}}{\mathrm{\&Gamma;}}_0,p_{\max }\}$

$p_i^{(k+1)}=\min \{\frac{p_i^{\left(k\right)}}{{\mathrm{\&gamma;}}_i^{\left(k\right)}}{[{\mathrm{\&Gamma;}}_i+\ln \left(\frac{a_i{g}_{i,i}}{b_i{\mathrm{<figure-callout\; id="0"\; label="g"\; filenames="HDA0000118814280000031.png"\; state="\{\{state\}\}">g</figure-callout>}}_{0,i}}\right)]}^{+},p_{i\_\max }\},$ $\&ForAll;i>0$

In the formula

Represent the transmitting power after the k time iteration of grand user, Represent i Femtocell user through the transmitting power after the k time iteration,

Represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user, Represent i Femtocell user through the Signal to Interference plus Noise Ratio after the k time iteration, Γ ₀For representing the SINR of grand user preset _hValue, Γ _iBe the SINR of i Femtocell user preset _fValue, g _{I, i}Be the channel gain of i Femtocell user to corresponding Femtocell base station, a _iAnd b _iAll be that Femtocell user participates in the preset parameter in the utility function of game, a _iRepresent that i Femtocell user increases the weight of the income that is obtained after the transmitting power of oneself, b _iRepresent that i Femtocell user increases the weight of being paid a price after the transmitting power of oneself; Detailed description about the utility function of game can be referring to document " Power control in two-tier Femtocell networks. " (V.Chandrasekhar; J.G.Andrews; Etc.IEEE trans.Wireless Commun., Aug.2009, vol.8; No.8, pp.4316-4328.);

At the Signal to Interference plus Noise Ratio SINR that guarantees grand user _hPrerequisite under, each Femtocell user reaches self preset Signal to Interference plus Noise Ratio SINR as far as possible through the mode of participating in game _f

Whether the Femtocell user that its service is detected in each Femtocell base station reaches its preset Signal to Interference plus Noise Ratio SINR _f, and report to macro base station through IP network, be the performance that further guarantees whole network, if detecting grand user, macrocell base stations do not reach its preset Signal to Interference plus Noise Ratio SINR _h, or do not reach self preset Signal to Interference plus Noise Ratio SINR in the coverage _fThe Femtocell number of users increase, then broadcasting suppresses signal, after each Femtocell user receives the inhibition signal of macrocell base stations, upgrades the p of self _{I_max}: p _{I_max}=p _{I_max}-Δ p carries out the game iteration once more, obtains the transmitting power equilibrium point and carries out ul transmissions.Wherein Δ p is an adjustment amount, and size is set according to the actual requirements, the adjusting range of the size of Δ p during to reply Femtocell user maximum transmit power limit, and Δ p is more little then meticulous more to the restriction adjustment of Femtocell user's maximum transmission power.

On this basis,, reach its preset Signal to Interference plus Noise Ratio SINR grand user for further reduction does not reach the Femtocell number of users of presetting the Signal to Interference plus Noise Ratio value _hSituation under, the Femtocell access device judges whether the Femtocell user of its service reaches preset SINR _f, do not reach self preset Signal to Interference plus Noise Ratio SINR through IP network to the macrocell base stations report then _fFemtocell user's current Signal to Interference plus Noise Ratio SINR _FnWith preset Signal to Interference plus Noise Ratio SINR _fResidual quantity value Δ γ _i, macrocell base stations receives that each does not reach the delta γ of preset Signal to Interference plus Noise Ratio _i, and through the minimum residual quantity value of IP network broadcasting; The Femtocell access device judges whether the Signal to Interference plus Noise Ratio residual quantity of macro base station broadcasting is the residual quantity value of oneself reporting; If; Then notify corresponding Femtocell user to improve upper limit of emission power, participate in the game iteration once more, make said residual quantity value Δ γ through the game iteration by certain step delta p _iMore and more littler, reach himself preset Signal to Interference plus Noise Ratio SINR up to this Femtocell user _fThe size of Δ p is to the adjusting range of reply Femtocell user maximum transmission power, and is consistent with the Δ p in the aforementioned limitations process.In the said process, select not reach the Femtocell user of preset Signal to Interference plus Noise Ratio one by one, increase its upper limit of emission power.If macrocell base stations detects grand user SINR in this process _hReduce or do not reach self and preset Signal to Interference plus Noise Ratio SINR _fThe quantitative change of Femtocell number of users many, then macrocell base stations broadcasting suppresses signal, the Femtocell user's that laststate upgraded maximum transmission power p _{I_max}Return to laststate, i.e. p _{I_max}=p _{I_max}-Δ p, the equilibrium value that game iteration is once more obtained is as transmitting power and finish whole process.

Proposition method of the present invention is under environment as shown in Figure 2, to carry out emulation, and D representes the distance between macrocell base stations and the grand user in the emulation; D _FThe distance of expression macrocell base stations and rectangular area, Femtocell place central point; D and DF handle through normalization; SUE refers to Femtocell user, and PUE refers to grand user.

Fig. 3 is guaranteeing under the grand user performance prerequisite; Femtocell user's Signal to Interference plus Noise Ratio SINR performance comparison diagram of the inventive method and existing method OA, wherein LP-LTPSA refers to the inventive method, the method LP-LTPSA that the present invention proposes is when reaching equilibrium; Femtocell user's SINR performance is superior to existing method OA; Though at D=0.9, under the distribution situation of DF=0.1, the Femtocell number of users is 64 o'clock; It is more lower slightly than existing method OA that the present invention proposes method SINR performance; Reach self preset SINR value but but exchange more Femtocell user for, as shown in Figure 4, can find out that method LP-LTPSA that the present invention proposes does not reach Femtocell user's percentage performance and all is superior to having now method OA when reaching equilibrium.

Claims (3)

1. the distributed power control method of a Femtocell up link; It is characterized in that based on game theory; To femtocell Fetomcell and macrocell base stations, guarantee that through the maximum transmission power that limits Fetomcell user the grand user of macrocell base stations reaches its preset Signal to Interference plus Noise Ratio SINR _h, make more Femtocell users reach self preset Signal to Interference plus Noise Ratio SINR through the game iteration on this basis _f, be specially: according to noise σ in the macrocell base stations covering marginal position grand user's in place the snr computation macrocellular ², the Signal to Interference plus Noise Ratio of establishing grand user is SINR _h, the Femtocell total number of users is M, all Fetomcell users are I to the maximum of this grand user's interference sum _Max, have

P wherein _MaxBe grand user's maximum transmission power, g _0,0Be the channel gain of grand user to macrocell base stations, then each Femtocell user is no more than the average interference value to the maximum interference that grand user produced:

If i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, g wherein _{0, i}Be the channel gain of i Femtocell user, I is then arranged to macrocell base stations _i≤I _Mean, i.e. p _ig _{0, i}≤I _Mean,

The transmitting power strategy that obtains Femtocell user is p _i=[0, p _{I_max}], promptly transmitting power [0, p _{I_max}] in, each Femtocell user participates in the game iteration according to own corresponding transmitting power strategy, and the transmitting power when drawing equilibrium is carried out ul transmissions:

$p_0^{(k+1)}=\min \{\frac{p_0^{\left(k\right)}}{{\mathrm{\&gamma;}}_0^{\left(k\right)}}{\mathrm{\&Gamma;}}_0,p_{\max }\}$

$p_i^{(k+1)}=\min \{\frac{p_i^{\left(k\right)}}{{\mathrm{\&gamma;}}_i^{\left(k\right)}}{[{\mathrm{\&Gamma;}}_i+\ln \left(\frac{a_i{g}_{i,i}}{b_i{g}_{0,i}}\right)]}^{+},p_{i\_\max }\},$ $\&ForAll;i>0$

In the formula Represent the transmitting power after the k time iteration of grand user,

Represent i Femtocell user through the transmitting power after the k time iteration,

Represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user, Represent i Femtocell user through the Signal to Interference plus Noise Ratio after the k time iteration, Γ ₀For representing the SINR of grand user preset _hValue, Γ _iBe the SINR of i Femtocell user preset _fValue, g _{I, i}Be the channel gain of i Femtocell user to corresponding Femtocell base station, a _iRepresent that i Femtocell user increases the weight of the income that is obtained after the transmitting power of oneself, b _iRepresent that i Femtocell user increases the weight of being paid a price after the transmitting power of oneself;

At the Signal to Interference plus Noise Ratio SINR that guarantees grand user _hPrerequisite under, each Femtocell user reaches self preset Signal to Interference plus Noise Ratio SINR as far as possible through the mode of participating in game _f

2. the distributed power control method of a kind of Femtocell up link according to claim 1 is characterized in that whether the Femtocell user of each Femtocell base station its service of detection reaches its preset Signal to Interference plus Noise Ratio SINR _f, and report to macro base station through IP network, macrocell base stations detects grand user and does not reach its preset Signal to Interference plus Noise Ratio SINR _h, or do not reach self preset Signal to Interference plus Noise Ratio SINR in the coverage _fThe Femtocell number of users increase, then broadcasting suppresses signal, after each Femtocell user receives the inhibition signal of macrocell base stations, upgrades the p of self _{I_max}: p _{I_max}=p _{I_max}-Δ p, Δ p are adjustment amount, and size is set according to the actual requirements, carry out the game iteration once more, obtain the transmitting power equilibrium point and carry out ul transmissions.

3. the distributed power control method of a kind of Femtocell up link according to claim 1 and 2 is characterized in that reaching its preset Signal to Interference plus Noise Ratio SINR grand user _hSituation under, do not reach self preset Signal to Interference plus Noise Ratio SINR _fFemtocell user report its current Signal to Interference plus Noise Ratio SINR through its Femtocell base station to macrocell base stations _FnWith preset Signal to Interference plus Noise Ratio SINR _fResidual quantity value Δ γ _i, macrocell base stations is notified wherein residual quantity value Δ γ _iMinimum Femtocell user increases upper limit of emission power by the adjustment amount Δ p that sets and participates in the game iteration once more, makes said residual quantity value Δ γ through the game iteration _iMore and more littler, reach himself preset Signal to Interference plus Noise Ratio SINR up to this Femtocell user _f

Images