CN101917768B - User fairness resource allocation method for orthogonal frequency division multiple access relay system - Google Patents

Abstract

The invention discloses a user fairness resource allocation method for an orthogonal frequency division multiple access relay system. The method is characterized by comprising the following steps of: jointly optimizing relay selection, subcarrier allocation and power allocation; selecting a most appropriate relay for each subcarrier; allocating the relay to an optimal relay-user link; allowing a base station and each relay to perform self-adaptive power allocation on each subcarrier; and introducing a power adjustment factor and performing iteration repeatedly to ensure the convergence of total power and optimize the throughput of the system. A target is to ensure user fairness during the selection of the optimal link and the average speed of users is taken as an investigation variable during power allocation. The method of the invention optimizes the throughput of the system and can ensure approximately strict fairness among the users.

Description

A kind of user fairness resource allocation method of orthogonal frequency division multiple access relay system

Technical field

The invention belongs to OFDM access (OFDMA) mobile communication technology field, particularly guarantee the resource allocation methods of user fairness in the OFDMA relay communications system.

Background technology

The OFDMA technology can take full advantage of multi-user diversity according to the independence of different user channel fading, improves spectrum efficiency.On the other hand, adopt relaying technique can increase the coverage of wireless network, improve power system capacity and reliability.Therefore, OFDMA technology and relaying technique are the core technologies of following mobile radio system.How carrying out rational resource distribution in the OFDMA relay system is a more and more important research topic.

" international electronics communicate by letter with the Institution of Electrical Engineers the selected topic magazine " (IEEE J.on Select Areas.Commun, Volume 17, No 10,1999, pp 1747-1758) in mentioned Multi User Adaptive subcarrier, bit and power allocation algorithm in a kind of OFDMA system.This algorithm application scene conventional cellular cell that is non-relay node but, and in the OFDMA relay system, to select suitable via node the transmission of data to different users, and need simultaneously subcarrier and power division to be carried out in base station and via node, so this algorithm can't be applied in the OFDMA relay system.

At " international electronics communicate by letter with the Institution of Electrical Engineers the selected topic magazine " (IEEE J.on Select Areas.Commun, Volume 25, No 2,2007, pp 328-339) a kind of adaptive subcarrier for the OFDMA relay system and power distribution algorithm have also been mentioned in, but the target of this algorithm is maximization system total utility, does not consider the fairness problem between the user.And guarantee between the user fairness, be multi-user services better, be one of core objective of future broadband wireless communication systems, guarantee therefore between the user that the resource of fairness divides that to match future broadband wireless communication systems significant.

Summary of the invention

The objective of the invention is to propose a kind of user fairness resource allocation method of orthogonal frequency division multiple access relay system, the method can guarantee to have between the user approximate strict fairness in the optimization system throughput.

The user fairness resource allocation method of orthogonal frequency division multiple access relay system of the present invention, the base station is according to system parameters and the channel parameter of input, through following treatment step, by the resource allocation result that single-chip microcomputer output obtains, it is characterized in that the base station end carries out following steps successively:

The first step: establishing time-gap number is t, for each user m=1 in the system ..., M, with

Be illustrated in the Mean Speed of the user m that time slot t calculates, the Mean Speed of initialization user m when time slot t=0

Be nonnegative value, M is the total number of users in the system;

Second step: establishing the iteration round is i, for each via node k=1 ..., K is with μ _k(i) expression via node k is in the power adjusting factor of iteration round i, and η (i) expression base station is in the power adjusting factor of iteration round i, and initialization via node k is at the power adjusting factor μ of iteration round i=0 _k(0) and the base station be nonnegative number at the power adjusting factor η (0) of iteration round i=0, K is the via node number in the system;

Base station s upgrades canned data according to the channel condition information of via node feedback: for all via node k=1 ..., K, and user m=1 ..., M upgrades the channel gain that the base station is produced by multipath fading on subcarrier n to s via node k

Upgrade the channel gain that via node k is produced by multipath fading on subcarrier n to user m

Upgrade the path loss l between base station s and the via node k _Sk, upgrade the path loss l between via node k and the user m _Km

The 3rd step: note system sub-carriers adds up to N, for each subcarrier n=1 ..., N is according to current each user's Mean Speed

Base station power is adjusted factor η (i), relaying power adjusting factor μ _kAnd the channel gain that on subcarrier n, produced by multipath fading to via node k of base station s (i),

The channel gain that via node k is produced by multipath fading on subcarrier n to user m Path loss l between base station s and the via node k _Sk, the path loss between via node k and the user m is calculated respectively current power distribution result and the allocation result of this carrier wave on link on this carrier wave;

Draw power distribution result by following listed via node k to the transmitting power formula (1) of user m on subcarrier n:

$p_{\mathrm{km}}^n={[\frac{W/2N}{{\mathrm{\Φ}}_{\mathrm{km}}^n{\stackrel{\‾}{R}}_m\left(t\right)\ln 2}-\frac{1}{g_{\mathrm{km}}^n}]}^{+}---\left(1\right)$

W is overall system bandwidth in the formula (1), is divided into N subcarrier, operator [x] ⁺=max{x, 0} namely represents the higher value in peek value x and 0, previous intermediate variable

With a rear intermediate variable

Be respectively

${\mathrm{\Φ}}_{\mathrm{km}}^n={\mathrm{\μ}}_k\left(i\right)=\frac{\mathrm{\η}\left(i\right)l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{l_{\mathrm{sk}}{\left|h_{\mathrm{sk}}^n\right|}^2}---\left(2\right)$

$g_{\mathrm{km}}^n=\frac{l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{\mathrm{\Γ}{\mathrm{WN}}_0/N}---\left(3\right)$

N in the formula (3) ₀Be the single-side belt noise power spectral density in the system, signal to noise ratio gap Γ is the function of target bit BER, Γ=-ln (5BER)/1.5;

The via node k that tries to achieve at the transmitting power formula (1) on the subcarrier n to user m according to via node k is to the transmitting power of user m on subcarrier n Value, calculate via node k to the transmission rate of user m on subcarrier n

$r_{\mathrm{km}}^n=\frac{W}{2N}\mathrm{lo}{g}_2(1+\frac{p_{\mathrm{km}}^n{l}_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{\mathrm{\ΓW}{N}_0/N})---\left(4\right)$

The transmission rate of trying to achieve to the transmission rate formula (4) of user m on subcarrier n according to via node k

Carrying out subcarrier distributes: for certain subcarrier n, at first choose

Maximum (k, m) combination, namely

$(k^{*},m^{*})=\arg \underset{k,m}{\max }\frac{r_{\mathrm{km}}^n}{{\stackrel{\‾}{R}}_m\left(t\right)}---\left(5\right)$

Then subcarrier n is distributed to the (k that chooses ^*, m ^*), namely distribute to via node k ^*To user m ^*Link; The indicator variable of definition expression allocation of carriers

Expression is distributed to via node k to the link of user m with carrier wave n, otherwise, indicator variable

For via node k ^*To user m ^*Link, indicator variable

And for via node k ^*To user m ^*Other links in addition are namely for via node k ≠ k ^*To user m ≠ m ^*Link, indicator variable

Be formulated as:

${\mathrm{\ρ}}_{k^{*}{m}^{*}}^n=1,{\mathrm{\ρ}}_{\mathrm{km}}^n=0,\∀k\≠k^{*},m\≠m^{*}---\left(6\right)$

Then the base station is calculated by following formula to the transmitting power of via node k on subcarrier n:

$p_{\mathrm{sk}}^n=\frac{l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{l_{\mathrm{sk}}{\left|h_{\mathrm{sk}}^n\right|}^2}{p}_{\mathrm{km}}^n,$ When ${\mathrm{\ρ}}_{\mathrm{km}}^n=1$ The time (7)

The 4th step: upgrade iteration round i=i+1, and the formula below adopting is upgraded relaying and base station power is adjusted the factor

${\mathrm{\μ}}_k(i+1)={[{\mathrm{\μ}}_k\left(i\right)-{\mathrm{\α}}_1\left(i\right)(P_k^{\max }-\underset{m=1}{\overset{M}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{\mathrm{km}}^n)]}^{+},k=1,...,K---\left(8\right)$

$\mathrm{\η}(i+1)={[\mathrm{\η}\left(i\right)-{\mathrm{\α}}_2\left(i\right)(P_{\mathrm{BS}}^{\max }-\underset{m=1}{\overset{M}{\mathrm{\Σ}}}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{\mathrm{sk}}^n)]}^{+}---\left(9\right)$

Wherein The maximum power constraint of expression via node k,

The maximum power constraint of expression base station, α ₁(i) and α ₂(i) be iteration step length;

The 5th step: according to new formula (8) and the base station power adjustment factor result of calculation of new formula (9) more more of the relaying power adjusting factor in the 4th step, judge whether transmitting power restrains, if do not restrain, then returned for the 3rd step, if convergence entered for the 6th step;

The 6th step: for user m=1 ..., M goes on foot carrier wave and the power distribution result that the 5th step iterative computation obtains according to front the 3rd, by the momentary rate computing formula

$R_m\left(t\right)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{km}}^n{r}_{\mathrm{km}}^n,$ m＝1，...，M (10)

Calculate current momentary rate R _m(t), and by Mean Speed

Computing formula

${\stackrel{\‾}{R}}_m(t+1)=(1-\frac{1}{T}){\stackrel{\‾}{R}}_m\left(t\right)+\frac{1}{T}{R}_m\left(t\right)---\left(11\right)$

Upgrade Mean Speed

T is sliding window length in the formula;

The 7th step: upgrade time slot t=t+1, return the Resource Allocation Formula that second step calculates next time slot.

Compare with the existing resource distribution technique, what resource dispense needles of the present invention was right is the multi-user who is of universal significance in the future communications, many relay systems, and is to distribute in the resource that guarantees to carry out in the fairness situation between the downlink communication user.Relay selection, the subcarrier that relates in the resource allocation process distributed in the present invention and the power division problem is carried out combined optimization, and based on resolution theory and protruding optimum theory, has provided optimum resource allocation methods.Because the present invention is the only relaying of each sub-carrier selection, and it is distributed to optimum relaying-user link, base station and each relaying carry out the adaptive power distribution at each subcarrier simultaneously, by introducing power adjusting factor, through the several times iteration, can guarantee gross power convergence, throughput that therefore can optimization system.Simultaneously, when selecting optimum link, be to guarantee that fairness is target between the user in the present invention underway continue selection and the allocation of carriers process, when carrying out power division simultaneously also the Mean Speed with the user investigate variable as one of them, therefore can guarantee that resource is distributed approximate strict fairness between the user.To sum up, the resource allocation methods that the present invention proposes not only can the optimization system throughput, can guarantee to have between the user simultaneously approximate strict fairness.

Description of drawings

Fig. 1 is the theory diagram of the resource allocation methods of OFDM access relay communications system of the present invention;

Fig. 2 is the system for implementing hardware figure of the resource allocation methods of OFDM access relay communications system of the present invention;

Fig. 3 is throughput of system comparison diagram under two kinds of algorithms;

Fig. 4 is user fairness comparison diagram under two kinds of algorithms.

Embodiment

Below in conjunction with description of drawings embodiment of the present invention.

Embodiment 1:

Present embodiment adopts descending OFDAM relay cellular network, and radius of society is 1km, and interior ring radius is 0.6km, and each via node is evenly distributed on the interior ring, and user's position produces at random, and is evenly distributed between the inner and outer ring.Concrete simulation parameter arranges as shown in table 1.The average result that 1000 resources of emulation statistics are distributed is investigated the performance of the resource allocation methods that this patent proposes from throughput of system and user fairness two aspects.

The setting of table 1. parameter

Present embodiment is carried out following concrete operation step successively at the base station end:

The first step: establishing time-gap number is t, for each user m=1 in the system ..., M, with

Be illustrated in the Mean Speed of the user m that time slot t calculates, the Mean Speed of initialization user m when time slot t=0

Be nonnegative value, M is the total number of users in the system;

Second step: establishing the iteration round is i, for each via node k=1 ..., K is with μ _k(i) expression via node k is in the power adjusting factor of iteration round i, and η (i) expression base station is in the power adjusting factor of iteration round i, and initialization via node k is at the power adjusting factor μ of iteration round i=0 _k(0) and the base station be nonnegative number at the power adjusting factor η (0) of iteration round i=0, K is the via node number in the system;

Canned data is upgraded according to the channel condition information of via node feedback in the base station: for all via node k=1 ..., K, and user m=1 ..., M upgrades the channel gain that the base station is produced by multipath fading on subcarrier n to via node k

Upgrade the channel gain that via node k is produced by multipath fading on subcarrier n to user m

Upgrade the path loss l between base station and the via node k _Sk, upgrade the path loss l between via node k and the user m _Km

The 3rd step: note system sub-carriers adds up to N, for each subcarrier n=1 ..., N is according to current each user's Mean Speed

Base station power is adjusted factor η (i), relaying power adjusting factor μ _kAnd the channel gain that on subcarrier n, produced by multipath fading to via node k of base station (i),

The channel gain that via node k is produced by multipath fading on subcarrier n to user m Path loss l between base station and the via node k _Sk, the path loss between via node k and the user m is calculated respectively current power distribution result and the allocation result of this carrier wave on link on this carrier wave;

Draw power distribution result by following formula: via node k is to the transmitting power of user m on subcarrier n

$p_{\mathrm{km}}^n={[\frac{W/2N}{{\mathrm{\Φ}}_{\mathrm{km}}^n{\stackrel{\‾}{R}}_m\left(t\right)\ln 2}-\frac{1}{g_{\mathrm{km}}^n}]}^{+}---\left(1\right)$

W is overall system bandwidth in the formula (1), is divided into N subcarrier, operator [x] ⁺=max{x, 0} namely represents the higher value in peek value x and 0, previous intermediate variable

With a rear intermediate variable Be respectively

${\mathrm{\Φ}}_{\mathrm{km}}^n={\mathrm{\μ}}_k\left(i\right)+\frac{\mathrm{\η}\left(i\right)l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{l_{\mathrm{sk}}{\left|h_{\mathrm{sk}}^n\right|}^2}---\left(2\right)$

$g_{\mathrm{km}}^n=\frac{l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{\mathrm{\ΓW}{N}_0/N}---\left(3\right)$

N in the formula (3) ₀Be the single-side belt noise power spectral density in the system, signal to noise ratio gap Γ is the function of target bit BER, Γ=-ln (5BER)/1.5;

The via node k that tries to achieve at the transmitting power formula (1) on the subcarrier n to user m according to via node k is to the transmitting power of user m on subcarrier n

Value, calculate via node k to the transmission rate of user m on subcarrier n

$r_{\mathrm{km}}^n=\frac{W}{2N}\mathrm{lo}{g}_2(1+\frac{p_{\mathrm{km}}^n{l}_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{\mathrm{\ΓW}{N}_0/N})---\left(4\right)$

The transmission rate of trying to achieve to the transmission rate formula (4) of user m on subcarrier n according to via node k

Carrying out subcarrier distributes: for certain subcarrier n, at first choose

Maximum (k, m) combination, namely

$(k^{*},m^{*})=\arg \underset{k,m}{\max }\frac{r_{\mathrm{km}}^n}{{\stackrel{\‾}{R}}_m\left(t\right)}---\left(5\right)$

Then subcarrier n is distributed to the (k that chooses ^*, m ^*), namely distribute to via node k ^*To user m ^*Link; The indicator variable of definition expression allocation of carriers

Expression is distributed to via node k to the link of user m with carrier wave n, otherwise, indicator variable

For via node k ^*To user m ^*Link, indicator variable

And for via node k ^*To user m ^*Other links in addition are namely for via node k ≠ k ^*To user m ≠ m ^*Link, indicator variable

Be formulated as follows:

${\mathrm{\ρ}}_{k^{*}{m}^{*}}^n=1,{\mathrm{\ρ}}_{\mathrm{km}}^n=0,\∀k\≠k^{*},m\≠m^{*}---\left(6\right)$

Then the base station is calculated by following formula to the transmitting power of via node k on subcarrier n:

$p_{\mathrm{sk}}^n=\frac{l_{\mathrm{km}}{\left|h_{\mathrm{km}}^n\right|}^2}{l_{\mathrm{sk}}{\left|h_{\mathrm{sk}}^n\right|}^2}{p}_{\mathrm{km}}^n,$ When ${\mathrm{\ρ}}_{\mathrm{km}}^n=1$ The time (7)

The 4th step: upgrade iteration round i=i+1, and the formula below adopting is upgraded relaying and base station power is adjusted the factor

${\mathrm{\μ}}_k(i+1)={[{\mathrm{\μ}}_k\left(i\right)-{\mathrm{\α}}_1\left(i\right)(P_k^{\max }-\underset{m=1}{\overset{M}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{\mathrm{km}}^n)]}^{+},k=1,...,K---\left(8\right)$

$\mathrm{\η}(i+1)={[\mathrm{\η}\left(i\right)-{\mathrm{\α}}_2\left(i\right)(P_{\mathrm{BS}}^{\max }-\underset{m=1}{\overset{M}{\mathrm{\Σ}}}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{\mathrm{sk}}^n)]}^{+}---\left(9\right)$

Wherein The maximum power constraint of expression via node k,

The maximum power constraint of expression base station, α ₁(i) and α ₂(i) be iteration step length;

The 5th step: according to new formula (8) and the base station power adjustment factor result of calculation of new formula (9) more more of the relaying power adjusting factor in the 4th step, judge whether transmitting power restrains, if do not restrain, then returned for the 3rd step, if convergence entered for the 6th step;

The 6th step: for user m=1 ..., M goes on foot carrier wave and the power distribution result that the 5th step iterative computation obtains according to front the 3rd, by the momentary rate computing formula

$R_m\left(t\right)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{km}}^n{r}_{\mathrm{km}}^n,$ m＝1，...，M (10)

Calculate current momentary rate R _m(t), and by Mean Speed

Computing formula

${\stackrel{\‾}{R}}_m(t+1)=(1-\frac{1}{T}){\stackrel{\‾}{R}}_m\left(t\right)+\frac{1}{T}{R}_m\left(t\right)---\left(11\right)$

Upgrade Mean Speed

T is sliding window length in the formula;

The 7th step: upgrade time slot t=t+1, return the Resource Allocation Formula that second step calculates next time slot.

Accompanying drawing 1 is the theory diagram of the resource allocation methods of OFDM access relay communications system of the present invention: at the base station end, initialization step 1 is in initial time initialization time-gap number t=0, each user's of initialization Mean Speed

Be nonnegative value; Channel step of updating 2 initialization iteration round i=0, initialization relaying power adjusting factor μ _k(0), k=1 ..., it is nonnegative number that K and base station power are adjusted factor η (0), upgrades channel condition information; Resource allocation step 3 is to each subcarrier, respectively according to the transmitting power computing formula (1) of via node, previous intermediate variable

Computing formula (2), a rear intermediate variable Computing formula (3) calculate the relaying power distribution result, calculate link rate according to transmission rate formula (4) afterwards, and according to link choose formula (5), allocation of carriers formula (6) is tried to achieve this allocation of carriers result, obtains the base station power allocation result by base station transmitting power computing formula (7) at last; Iterative step 4 upgrades iteration round i=i+1, and according to the relaying power adjusting factor more new formula (8), base station power adjust the factor more new formula (9) upgrade respectively relaying and base station power is adjusted factor mu _k(i) and η (i); Convergence discriminating step 5 judges whether transmitting power restrains, if do not restrain, then returns resource allocation step 3, if convergence, ingress rate step of updating 6; Carrier wave and power distribution result that speed step of updating 6 obtains to convergence discriminating step 5 iterative computation according to resource allocation step 3, calculate current momentary rate according to momentary rate computing formula (10), and according to Mean Speed more new formula (11) upgrade Mean Speed; Time slot step of updating 7 is upgraded time slot t=t+1, and Return Channel step of updating 2 is calculated the Resource Allocation Formula of next time slot.

Fig. 2 is the system for implementing hardware schematic diagram of the resource allocation methods of OFDM access relay communications system of the present invention, and this realization system comprises MSC-51 Chip Microcomputer A, Peripheral Interface RS-232C, Erasable Programmable Read Only Memory EPROM EPROM and random access memory ram.Erasable Programmable Read Only Memory EPROM EPROM and random access memory ram are connected on the Chip Microcomputer A, and Chip Microcomputer A and Peripheral Interface RS-232C interconnect.The input parameter of realization system comprises each system parameters B: total bandwidth W, number of sub carrier wave N, signal to noise ratio gap Γ, noise power spectral density N are arranged ₀, relaying maximum power constraint

Base station maximum power constraint

The number K of via node and number of users M; Also comprise for all via node k=1 ..., K and user m=1 ..., M, at each subcarrier n=1 ..., the channel parameter C on the N: the channel gain that has the base station to be produced by multipath fading on subcarrier n to via node k

The channel gain that via node k is produced by multipath fading on subcarrier n to user m

Path loss l between base station and the via node k _SkAnd the path loss l between via node k and the user m _KmThe realization system is output as for all via node k=1 ..., K and user m=1 ..., M, at each subcarrier n=1 ..., the resource allocation result D on the N: have indication carrier wave n whether to distribute to via node k to the allocation of carriers indicator variable of user m link

Via node k is to the transmitting power of user m on subcarrier n

And the base station is to the transmitting power of via node k on subcarrier n

System parameters B and channel parameter C are input to Chip Microcomputer A by Peripheral Interface RS-232C, obtain resource allocation result D through calculation process, the result is exported by Peripheral Interface RS-232C by Chip Microcomputer A.

The performance of resource allocation methods of the present invention is compared with a kind of method of heuritic approach that adopts of commonly using.In the method for contrast, the via node the transmission of data that each user selection is nearest with it, adopting greedy algorithm to carry out subcarrier distributes, be about to each subcarrier and distribute to the best user of channel condition thereon, and base station and each relaying mean allocation power on each carrier wave of their transmission.The below investigates the performance of method from throughput of system and user fairness two aspects.

Accompanying drawing 3 has provided under two kinds of algorithms the change curve with number of users change system throughput.The curve of top curve a for adopting resource allocation methods of the present invention to obtain, the curve of following curve b for adopting control methods to obtain.As can be seen from the figure, under different user was counted situation, the throughput of system performance that adopts resource allocation methods of the present invention to obtain all surpassed control methods.This is because method of the present invention is selected suitable relaying for each carrier wave, and carries out self adaptation and distribute power, has improved throughput of system.

Adopt fairness factor to investigate the fairness of algorithm, FI is as follows for the definition fairness factor

$\mathrm{FI}={\left(\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\stackrel{\‾}{S}}_m\right)}^2/\left(M\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\left({\stackrel{\‾}{S}}_m\right)}^2\right)---\left(12\right)$

Wherein

Be the Mean Speed of user m through 1000 resource distribution.When all user's Mean Speeds equated, the value of fairness factor was 1.More near 1, illustrate that fairness is better between the user.

Accompanying drawing 4 has provided two kinds of algorithms fairness factor change curve under the different user number, and wherein top curve c is the curve that adopts resource allocation methods of the present invention to obtain, the curve of following curve d for adopting control methods to obtain.As seen, under different user is counted situation, adopt user fairness sex factor that resource allocation methods of the present invention obtains all very near 1, illustrate when having different number user in the system, method of the present invention all can guarantee each user's Mean Speed approximately equal, has approximate strict fairness.And can find out that from the fairness factor curve that adopts control methods to obtain along with number of users increases, fairness descends rapidly.This is because the greedy algorithm distributing carrier wave is adopted in control methods, and when number of users increased, some users that are in cell edge can't obtain carrier resource because channel status is poor always.

Claims (1)

1. the user fairness resource allocation method of an orthogonal frequency division multiple access relay system, the base station is according to system parameters and the channel parameter of input, through following treatment step, by the resource allocation result that single-chip microcomputer output obtains, it is characterized in that the base station end carries out following steps successively:

The first step: establishing time-gap number is t, for each user m=1 in the system ..., M, with Be illustrated in the Mean Speed of the user m that time slot t calculates, the Mean Speed of initialization user m when time slot t=0

Be nonnegative value, M is the total number of users in the system;

Second step: establishing the iteration round is i, for each via node k=1 ..., K is with μ _k(i) expression via node k is in the power adjusting factor of iteration round i, and η (i) expression base station is in the power adjusting factor of iteration round i, and initialization via node k is at the power adjusting factor μ of iteration round i=0 _k(0) and the base station be nonnegative number at the power adjusting factor η (0) of iteration round i=0, K is the via node number in the system;

Base station s upgrades canned data according to the channel condition information of via node feedback: for all via node k=1 ..., K, and user m=1 ..., M upgrades the channel gain that base station s is produced by multipath fading on subcarrier n to via node k

Upgrade the channel gain that via node k is produced by multipath fading on subcarrier n to user m Upgrade the path loss l between base station s and the via node k _Sk, upgrade the path loss l between via node k and the user m _Km

The 3rd step: note system sub-carriers adds up to N, for each subcarrier n=1 ..., N is according to current each user's Mean Speed

Base station power is adjusted factor η (i), relaying power adjusting factor μ _kAnd the channel gain that on subcarrier n, produced by multipath fading to via node k of base station s (i),

The channel gain that via node k is produced by multipath fading on subcarrier n to user m

Path loss l between base station s and the via node k _Sk, the path loss between via node k and the user m is calculated respectively current power distribution result and the allocation result of this carrier wave on link on this carrier wave;

Draw power distribution result by following listed via node k to the transmitting power formula (1) of user m on subcarrier n:

W is overall system bandwidth in the formula (1), is divided into N subcarrier, operator [x] ⁺=max{x, 0} namely represents the higher value in peek value x and 0, previous intermediate variable

With a rear intermediate variable

Be respectively

N in the formula (3) ₀Be the single-side belt noise power spectral density in the system, signal to noise ratio gap Γ is the function of target bit BER, Γ=-ln (5BER)/1.5;

The via node k that tries to achieve at the transmitting power formula (1) on the subcarrier n to user m according to via node k is to the transmitting power of user m on subcarrier n Value, calculate via node k to the transmission rate of user m on subcarrier n

The transmission rate of trying to achieve to the transmission rate formula (4) of user m on subcarrier n according to via node k

Carrying out subcarrier distributes: for certain subcarrier n, at first choose

Maximum (k, m) combination, namely

Then subcarrier n is distributed to the (k that chooses ^*, m ^*), namely distribute to via node k ^*To user m ^*Link; The indicator variable of definition expression allocation of carriers

Expression is distributed to via node k to the link of user m with carrier wave n, otherwise, indicator variable

For via node k ^*To user m ^*Link, indicator variable

And for via node k ^*To user m ^*Other links in addition are namely for via node k ≠ k ^*To user m ≠ m ^*Link, indicator variable

Be formulated as:

Then the base station is calculated by following formula to the transmitting power of via node k on subcarrier n:

When

The time (7)

The 4th step: upgrade iteration round i=i+1, and the formula below adopting is upgraded relaying and base station power is adjusted the factor

Wherein

The maximum power constraint of expression via node k, The maximum power constraint of expression base station, α ₁(i) and α ₂(i) be iteration step length;

The 5th step: according to new formula (8) and the base station power adjustment factor result of calculation of new formula (9) more more of the relaying power adjusting factor in the 4th step, judge whether transmitting power restrains, if do not restrain, then returned for the 3rd step, if convergence entered for the 6th step;

The 6th step: for user m=1 ..., M goes on foot carrier wave and the power distribution result that the 5th step iterative computation obtains according to front the 3rd, by the momentary rate computing formula

m＝1，...，M (10)

Calculate current momentary rate R _m(t), and by Mean Speed

Computing formula

Upgrade Mean Speed

T is sliding window length in the formula;

The 7th step: upgrade time slot t=t+1, return the Resource Allocation Formula that second step calculates next time slot.

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