CN102421177B - 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, is 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, according to 3G development in recent years and broadband mobile trend, release, it is operated in mandate frequency range, by broadband access, as DSL, wire cable, optical fiber etc. are connected to the network of operator, in its Main Function Shi Wei family room or small-business mechanism provide better signal to cover and service quality.Mutual interference problem is the major issue that Femtocell will solve always.Due to frequency resource restriction, Femtocell and macrocell base stations adopt while disposing with frequency, have brought serious interference problem.

Game method element comprises game side, set of strategies, utility function etc.At present in game formula Femtocell Poewr control method, more lay particular emphasis on from utility function angle and reduce interlayer interference, and current Poewr control method more stresses the volumetric properties of network integral body, the Signal to Interference plus Noise Ratio SINR that has ignored each Femtocell user requires the situation that possibility is different, makes may exist more Femtocell user not reach its default SINR value in 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 proposing in, we are called primal algorithm (Original Algorithm), be abbreviated as OA method, existing a kind of based on game theoretic Femtocell Poewr control method, but it does not limit Femtocell user's maximum transmission power, make each user likely to grand user, produce larger interference, its link protection method reduces Femtocell user by reduction Femtocell user preset SINR value to be disturbed grand user, and this link protection method is accurate not to the identification of larger interference, its ways to restrain is inflexible, the Femtocell user who does not reach self default SINR value in network is more, Femtocell user's communication efficiency is undesirable.

Summary of the invention

The problem to be solved in the present invention is: in Femtocell technology, have mutual interference problem, existing Poewr control method has been ignored each Femtocell user's Signal to Interference plus Noise Ratio requirement, by reduction Femtocell user preset SINR value, reducing Femtocell user disturbs grand user, and the Femtocell user who does not reach self default SINR value in network is more, and Femtocell user's communication efficiency 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, by limiting Fetomcell user's maximum transmission power, guarantee that the grand user of macrocell base stations reaches its default Signal to Interference plus Noise Ratio SINR _h, by game iteration, make more Femtocell users reach self default Signal to Interference plus Noise Ratio SINR on this basis _f, be specially: according to noise σ in the macrocell base stations covering grand user's in marginal position place snr computation macrocellular ², the Signal to Interference plus Noise Ratio of establishing grand user is SINR _h, 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 _maxfor grand user's maximum transmission power, g _0,0for the channel gain of grand user to macrocell base stations, the maximum interference that each Femtocell user produces grand user is no more than average interference value: if i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, g wherein _{0, i}be the channel gain that i Femtocell user arrives macrocell base stations, have I _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}], transmitting power is at [0, p _{i_max}] in, each Femtocell user participates in game iteration according to own corresponding transmitting power strategy, and the transmitting power while 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 formula represent the transmitting power after the k time iteration of grand user, the transmitting power after the k time iteration that represents i Femtocell user, represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user, the Signal to Interference plus Noise Ratio after the k time iteration that represents i Femtocell user, Γ ₀for representing the SINR of grand user preset _hvalue, Γ _ibe the SINR of i Femtocell user preset _fvalue, g _{i, i}be that i Femtocell user is to the channel gain of corresponding Femtocell base station, a _irepresent that i Femtocell user increases the weight of the income obtaining after the transmitting power of oneself, b _irepresent that i Femtocell user increases the weight of paying 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 default Signal to Interference plus Noise Ratio SINR as far as possible by participating in the mode of game _f.

Whether the Femtocell user that its service is detected in each Femtocell base station reaches its default Signal to Interference plus Noise Ratio SINR _f, and report to macro base station by IP network, macrocell base stations detects grand user and does not reach its default Signal to Interference plus Noise Ratio SINR _h, or in coverage, do not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell number of users increase, broadcast Inhibitory signal, each Femtocell user receives after the Inhibitory signal of macrocell base stations, upgrades the p of self _{i_max}: p _{i_max}=p _{i_max}-Δ p, Δ p is adjustment amount, and size is set according to the actual requirements, again carries out game iteration, obtains transmitting power equilibrium point and carries out ul transmissions.

Further, grand user, reach its default Signal to Interference plus Noise Ratio SINR _hsituation under, do not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell user by its Femtocell base station, to macrocell base stations, report its current Signal to Interference plus Noise Ratio SINR _fnwith default 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 setting and again participates in game iteration, by game iteration, makes described residual quantity value Δ γ _imore and more less, until this Femtocell user reaches himself default Signal to Interference plus Noise Ratio SINR _f.

The present invention is guaranteeing under the prerequisite of power system capacity performance, by adjusting Femtocell user emission power higher limit, is carried out Femtocell user's power control by the mode of game, makes more Femtocell user reach self default SINR _fvalue.The present invention has considered different Femtocell users' different Signal to Interference plus Noise Ratio requirements, first controls the maximum I to grand user's interference sum _max, guarantee that grand user reaches its default Signal to Interference plus Noise Ratio SINR _h, then the mode by game makes each Femtocell user increase its transmitting power, reaches as far as possible himself default Signal to Interference plus Noise Ratio SINR _f.Compared with prior art, the present invention is guaranteeing under the prerequisite of power system capacity performance, makes more Femtocell user reach self default SINR value, and as shown in Figure 3 and Figure 4, the inventive method is compared existing method and had better performance.

Accompanying drawing explanation

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 schematic diagram separately thereof.

Fig. 3 is guaranteeing under grand user performance prerequisite, the 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 default Signal to Interference plus Noise Ratio percentage performance.

Embodiment

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

The inventive method, based on game theory, to femtocell Fetomcell and macrocell base stations, guarantees that by limiting Fetomcell user's maximum transmission power the grand user of macrocell base stations reaches its default Signal to Interference plus Noise Ratio SINR _h, by game iteration, make more Femtocell users reach self default Signal to Interference plus Noise Ratio SINR on this basis _f.As shown in Figure 1, the signal to noise ratio (SNR:Signal to Noise Ratio) of establishing the macrocellular covering grand user in marginal position place should reach 20dB, can calculate thus the noise σ in honeycomb ².If grand user's Signal to Interference plus Noise Ratio SINR _h=10dB, Femtocell total number of users is M, all Fetomcell users are I to the maximum of this grand user's interference sum _max, disturbing while being worth higher than this, this grand user's Signal to Interference plus Noise Ratio can be lower than 10dB, have p wherein _maxfor grand user's maximum transmission power, g _0,0for the channel gain of grand user to macrocell base stations.Consider fairness, the maximum interference that each Femtocell user produces grand user can not surpass average interference value: if i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, p wherein _ifor g _{0, i}be i Femtocell user's transmitting power, i Femtocell user arrives the channel gain of macrocell base stations, has I _i≤ I _mean, i.e. p _ig _{0, i}≤ I _mean, guarantee that, in grand user's SINR situation, Femtocell user's transmitting power strategy is p _i=[0, p _{i_max}], transmitting power is at [0, p _{i_max}] in, each Femtocell user participates in game iteration according to own corresponding transmitting power strategy, and the transmitting power while 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 formula represent the transmitting power after the k time iteration of grand user, the transmitting power after the k time iteration that represents i Femtocell user, represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user, the Signal to Interference plus Noise Ratio after the k time iteration that represents i Femtocell user, Γ ₀for representing the SINR of grand user preset _hvalue, Γ _ibe the SINR of i Femtocell user preset _fvalue, g _{i, i}be that i Femtocell user is to the channel gain of corresponding Femtocell base station, a _iand b _iall 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 obtaining after the transmitting power of oneself, b _irepresent that i Femtocell user increases the weight of paying 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 default Signal to Interference plus Noise Ratio SINR as far as possible by participating in the mode of game _f.

Whether the Femtocell user that its service is detected in each Femtocell base station reaches its default Signal to Interference plus Noise Ratio SINR _f, and report to macro base station by IP network, for further guaranteeing the performance of whole network not reach its default Signal to Interference plus Noise Ratio SINR if macrocell base stations detects grand user _h, or in coverage, do not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell number of users increase, broadcast Inhibitory signal, each Femtocell user receives after the Inhibitory signal of macrocell base stations, upgrades the p of self _{i_max}: p _{i_max}=p _{i_max}-Δ p, carries out game iteration again, obtains transmitting power equilibrium point and carries out ul transmissions.Wherein Δ p is 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 less meticulousr to the restriction adjustment of Femtocell user's maximum transmission power.

On this basis, for further reduction does not reach the Femtocell number of users of presetting Signal to Interference plus Noise Ratio value, grand user, reach its default Signal to Interference plus Noise Ratio SINR _hsituation under, Femtocell access device judges whether the Femtocell user of its service reaches default SINR _f, then by IP network, to macrocell base stations, report and do not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell user's current Signal to Interference plus Noise Ratio SINR _fnwith default Signal to Interference plus Noise Ratio SINR _fresidual quantity value Δ γ _i, macrocell base stations receives that each does not reach the residual quantity Δ γ of default Signal to Interference plus Noise Ratio _i, and broadcast minimum residual quantity value by IP network; Femtocell access device judges whether the Signal to Interference plus Noise Ratio residual quantity of macro base station broadcast is the residual quantity value of oneself reporting, if, notify corresponding Femtocell user to improve upper limit of emission power by certain step delta p, again participate in game iteration, by game iteration, make described residual quantity value Δ γ _imore and more less, until this Femtocell user reaches himself default Signal to Interference plus Noise Ratio SINR _f.The adjusting range of the size of Δ p to reply Femtocell user maximum transmission power is consistent with the Δ p in aforementioned limitations process.In said process, select not reach one by one the Femtocell user of default Signal to Interference plus Noise Ratio, 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, macrocell base stations broadcast Inhibitory 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 again obtained is as transmitting power and finish whole process.

Put forward the methods of the present invention is under environment as shown in Figure 2, to carry out emulation, and in emulation, D represents the distance between macrocell base stations and grand user; D _fthe distance that represents macrocell base stations and rectangular area, Femtocell place central point; D and DF are through normalized; SUE refers to Femtocell user, and PUE refers to grand user.

Fig. 3 is guaranteeing under 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 better than existing method OA, although at D=0.9, under the distribution situation of DF=0.1, Femtocell number of users is 64 o'clock, existing method OA is lower slightly for put forward the methods SINR Performance Ratio of the present invention, but but exchange more Femtocell user for and reach self default SINR value, 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 is all better than existing 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, by limiting Fetomcell user's maximum transmission power, guarantee that the grand user of macrocell base stations reaches its default Signal to Interference plus Noise Ratio SINR _h, by game iteration, make more Femtocell users reach self default Signal to Interference plus Noise Ratio SINR on this basis _f, be specially: according to noise σ in the macrocell base stations covering grand user's in marginal position place snr computation macrocellular ², the Signal to Interference plus Noise Ratio of establishing grand user is SINR _h, 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 _maxfor grand user's maximum transmission power, g _0,0for the channel gain of grand user to macrocell base stations, the maximum interference that each Femtocell user produces grand user is no more than average interference value: if i Femtocell user is I to grand user's interference _i=p _ig _{0, i}, p wherein _ibe i Femtocell user's transmitting power, _{g0, i}be the channel gain that i Femtocell user arrives macrocell base stations, have I _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}], transmitting power is at [0, p _{i_max}] in, each Femtocell user participates in game iteration according to own corresponding transmitting power strategy, and the transmitting power while 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 formula represent the transmitting power after the k time iteration of grand user, the transmitting power after the k time iteration that represents i Femtocell user, represent the Signal to Interference plus Noise Ratio after the k time iteration of grand user, the Signal to Interference plus Noise Ratio after the k time iteration that represents i Femtocell user, Γ ₀for representing the SINR of grand user preset _hvalue, Γ _ibe the SINR of i Femtocell user preset _fvalue, g _i,ibe that i Femtocell user is to the channel gain of corresponding Femtocell base station, a _irepresent that i Femtocell user increases the weight of the income obtaining after the transmitting power of oneself, b _irepresent that i Femtocell user increases the weight of paying 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 default Signal to Interference plus Noise Ratio SINR as far as possible by participating in the mode of game _f.

2. the distributed power control method of a kind of Femtocell up link according to claim 1, is characterized in that each Femtocell base station detects the Femtocell user of its service and whether reach its default Signal to Interference plus Noise Ratio SINR _f, and report to macro base station by IP network, macrocell base stations detects grand user and does not reach its default Signal to Interference plus Noise Ratio SINR _h, or in coverage, do not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell number of users increase, broadcast Inhibitory signal, each Femtocell user receives after the Inhibitory signal of macrocell base stations, upgrades the p of self _{i_max}: p _{i_max}=p _{i_max}-△ p, △ p is adjustment amount, and size is set according to the actual requirements, again carries out game iteration, obtains transmitting power equilibrium point and carries 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 in the situation that grand user reaches its default Signal to Interference plus Noise Ratio SINRh, does not reach self default Signal to Interference plus Noise Ratio SINR _ffemtocell user by its Femtocell base station, to macrocell base stations, report its current Signal to Interference plus Noise Ratio SINR _fn and default Signal to Interference plus Noise Ratio SINR _fresidual quantity value △ _{γ i}, macrocell base stations is notified wherein residual quantity value △ _{γ i}minimum Femtocell user is by the adjustment amount △ setting _pincrease upper limit of emission power and again participate in game iteration, by game iteration, make described residual quantity value △ _{γ i}more and more less, until this Femtocell user reaches himself default Signal to Interference plus Noise Ratio SINR _f.