CN101729206A - Conflict detection-based method for separating the threshold selection and cooperation conflict of detector - Google Patents

Abstract

The invention discloses a conflict detection-based method for separating the threshold selection and cooperation conflict of a detector, which is characterized in that in a small-sized time slot multiple access network transmitted by relay aid, firstly, forecasting the substantial output of a network according to the number of network users, packet sending probability of users, detection probability and false-alarm probability, obtaining the reciprocal relationship between the detection probability and the false-alarm probability by extremum operation to further obtain the optimal detector threshold; secondly, detecting conflict orders and active users according to time slots by a destination end, and notifying a judgment result to all network users by a control channel; and finally, determining the length of transmission time interval of data packets by the system according to the judgment result, and selecting corresponding trunk node aiding information source to transmit data packets, thereby realizing the separation of conflict data packets at the destination end by a sub-optimal linear solution.

Description

Select and cooperation conflict separation method based on the detector thresholding of collision detection

Technical field

The present invention relates to the small-sized time slot multi-access network of the auxiliary transmission of relaying, and the reception of carrying out the colliding data bag simultaneously with separate, particularly a kind of detector thresholding based on collision detection is selected and cooperation conflict separation method, belongs to network service and signal processing technology field.

Background technology

In wireless network, a large amount of uncertain channel variation, uneven traffic carrying capacity, radio node move that caused network configuration changes and to the requirement of broadband high-speed rate communication etc., communication system optimization and network design under the existence conditions have been constituted significant challenge.This challenge require we examine closely again existing network each assembly (insert from physical layer design to the MAC layer and the routing of route layer, from information source be compressed to chnnel coding and modulation, from the circuit stages resource allocation to the network level resource allocation) design philosophy and method.In the face of above-mentioned challenge, cause people's great interest thereby in recent years signal processing technology is introduced the performance that network effectively improves wireless network.Many bags based on conflict resolution receive (Multiple Packet Reception, MPR) the technology multiple access of examining closely the access network at random from a new angle inserts problem, conflict resolution in the network is converted into the Signal Separation problem solves, utilize signal processing technology and Internet resources to solve collision problem in the network jointly.Its basic thought is exactly to make network node have the function that receives a plurality of user data package simultaneously and they are effectively separated, rather than simply a plurality of packets that arrive simultaneously is used as conflict and all abandons.Node wraps the introducing of receiving ability more, will bring new opportunities and challenges to the design of procotol, improves the throughput of whole network and the transmission of minimizing packet effectively and waits for time delay, for realizing that the new generation of wireless wide-band communication system has great importance.

It is a kind of new method of using signal processing technology to solve data packet collisions problem in the wireless slotted random access network that the network assistance diversity multiple access that people such as Tsatsanis propose inserts (NDMA, Network-assisted DiversityMultiple Access) mechanism.This method utilizes Internet resources to obtain diversity performance, and adopts the method for Signal Separation to recover the colliding data bag, and this is at first signal processing to be combined with the network organizing technology, to improve the method for network performance.Yet NDMA mechanism causes its performance to be subjected to the very big restriction of radio channel state for the dependence that retransmits.

Collaboration diversity is as a kind of new model of space diversity, gets more and more people's extensive concerning once occurring.Its basic thought is the formal construction " virtual multi-antenna array " by shared antenna and other Internet resources between the multi-user, and produces the certain space diversity gain of cooperation acquisition by distributed treatment.Lin Rui and A.P.Petropulu etc. combine collaboration diversity with NDMA mechanism, proposed a kind of MAC agreement of high-throughput---ALLIANCES mechanism, for the many bags receptions that solve under the WLAN (wireless local area network) decline state provide new way.

In above-mentioned two mechanism, in case conflict takes place, destination need be adjudicated conflict exponent number and active user collection (user that promptly conflicts set), and this moment, the thresholding of detector was selected most importantly, and will be further the conflict bag re-transmission of system be exerted an influence with separating.The hypothesis that the conclusion of NDMA and ALLIANCES mechanism all can correctly be detected based on the conflict exponent number, in fact, the mistaken verdict of destination very likely takes place.Be the performance of accurate assessment, must consider nonideal collision detection and, but have not yet to see relevant report the influence of systematic function based on many packet receivers of cooperation system of NDMA.

Summary of the invention

The objective of the invention is deficiency at existing many bag method of reseptances in the small-sized time slot multi-access network of supporting the auxiliary transmission of relaying, propose a kind of method of separating, thereby improve many bags receptivity of wireless communication system effectively based on the selection of detector thresholding and the cooperation conflict of collision detection.Its advantage is: on the one hand, utilize many bags receiving ability of node to solve unavoidable data packet collisions problem in traditional random access protocol; On the other hand, utilize the transfer capability of relaying to reduce the re-transmission failure that causes because of the intrinsic fading characteristic of wireless channel and further solve the detector thresholding that relates to when conflict exponent number and active user collection detected and adjudicate and select problem.

For achieving the above object, the invention provides a kind of selection of detector thresholding and cooperation conflict separation method based on collision detection, this method has been broken the ideal hypothesis that the conflict exponent number can correctly be detected in traditional NDMA mechanism and the ALLIANCES mechanism, in cooperation conflict separation mechanism, the detector thresholding selects to take into account desirable collision detection and two kinds of situations of imperfect collision detection, according to network user's number, user's the probability of giving out a contract for a project, detection probability and false alarm probability are predicted the potential throughput of network, by asking the extreme value computing to obtain optimum derivative relation between detection probability and false alarm probability, and then try to achieve optimum detector thresholding; Then, destination detects conflict exponent number and active user collection at the conflict time slot according to this optimum thresholding, and by control channel court verdict is notified to the all-network user; System selects the auxiliary information source of corresponding relay node to carry out the transmission of packet, and then realizes the separation of colliding data bag at destination according to this specified data bag when transmission segment length as a result.

Technical scheme of the present invention is as follows: select and cooperation conflict separation method based on the detector thresholding of collision detection, it is characterized in that:

(1) at first, the probability of giving out a contract for a project, detection probability and false alarm probability according to network user's number, user are predicted the potential throughput of network, potential throughput is defined as in the potential unit time slot can successful data recovered bag, by asking the derivative relation between extreme value computing acquisition detection probability and false alarm probability, and then try to achieve the detector thresholding, step is as follows:

To be user buffer be empty probability zero hour period in transmission to definition Pe, when K user when conflicting time slot collision, its binary expression is as follows:

$P\left(K\right)=\left(\begin{array}{c}J\\ K\end{array}\right){(1-\mathrm{Pe})}^K{\mathrm{Pe}}^{J-K},K=\mathrm{0,1},...,J---\left(1\right)$

Wireless channel is modeled as the Rayleigh flat fading channel

Wherein, phase place

(n) [0,2 π) go up to obey evenly and distribute; Amplitude A _Ij(n) Rayleigh distributed, variance are 2 σ _A ²A _Ij(n) and

(n) separate, channel is obeyed independent same distribution, noise w between all users _r(n) be modeled as the white gaussian variable of incoherent return-to-zero average, variance is σ _v ²

False alarm probability P _FBe expressed as:

$P_F={\∫}_T^{\∞}\frac{x}{{\mathrm{\σ}}_v^2}\exp (-\frac{x^2}{{2\mathrm{\σ}}_v^2})\mathrm{dx}=\exp (-\frac{T^2}{{2\mathrm{\σ}}_v^2})---\left(3\right)$

Detection probability P _DBe expressed as:

$P_D={\∫}_T^{\∞}\frac{x}{{\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2}\exp (-\frac{x^2}{2({\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2)})\mathrm{dx}=\exp (-\frac{T^2}{2({\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2)})---\left(4\right)$

Making m represent can be by the quantity of correct detected information source node, and n represents by false-alarm to be the idle node quantity of active node, correspondingly, and the conflict exponent number that is detected

Equal m+n.When K-m information source omission, n free subscriber by the probability of false-alarm is:

$P_{\det \mathrm{ect}}(m,n)=\left(\begin{array}{c}K\\ m\end{array}\right){\left(P_D\right)}^m{(1-P_D)}^{K-m}\left(\begin{array}{c}J-K\\ n\end{array}\right){\left(P_F\right)}^n{(1-P_F)}^{J-K-n}---\left(5\right)$

Wherein, 0≤m≤K, 0≤n≤J-K.Therefore, all correct probability that detects promptly correctly detects all active users (m=K), and no free subscriber is shown by the probability tables of false-alarm (n=0):

P _detect(K，0)＝P _D ^K(1-P _F) ^J-K

Correspondingly, the lengths table of transmission period is shown:

$L(K,m,n)=\left\{\begin{array}{c}m+n,0\≤m\≤K,0\≤n\≤J-K,m+n\≠0\\ 1,m=0\mathrm{andn}=0\end{array}\right.---\left(7\right)$

When K information source conflict, the average length of transmission period is expressed as:

$\stackrel{\‾}{L}\left(K\right)=\underset{m=0}{\overset{K}{\mathrm{\Σ}}}\underset{n=0}{\overset{J-K}{\mathrm{\Σ}}}{P}_{\det \mathrm{ect}}(m,n)L(K,m,n)={\mathrm{KP}}_D+(J-K)P_F+{(1-P_D)}^K{(1-P_F)}^{J-K}---\left(8\right)$

The average length of transmission period is expressed as:

$\stackrel{\‾}{L}=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}P\left(K\right)\stackrel{\‾}{L}\left(K\right)={\mathrm{JP}}_F+J(1-\mathrm{Pe})(P_D-P_F){+[(1-\mathrm{Pe})(1-P_D)+\mathrm{Pe}(1-P_F)]}^J---\left(9\right)$

The assessment of potential throughput has two kinds of situations:

A) situation 1: when potential throughput is assessed, each mistaken verdict of hypothesis goal end all will cause transmitting losing of last all packets of period, therefore, only when destination is made right-on judgement, the transmission period is only useful, on the useful transmission period, K packet can correctly be recovered at most.At this moment, average potential recoverable bag is expressed as:

${\stackrel{\‾}{N}}_1=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}\mathrm{KP}\left(K\right)P_{\det \mathrm{ect}}(K,0)=J(1-\mathrm{Pe})P_D{[(1-\mathrm{Pe})P_D+\mathrm{Pe}(1-P_F)]}^{J-1}---\left(10\right)$

Potential throughput under the situation 1 is expressed as

${\mathrm{PTP}}_1=\frac{{\stackrel{\‾}{N}}_1}{\stackrel{\‾}{L}}---\left(11\right)$

B) situation 2: under this hypothesis, under the situation of destination mistake in judgment, still have some conflicting data bag fortunately to be detected.When K-m information source omission, there be m information source correctly to recover at the most.At this moment, average potential recoverable bag is expressed as

${\stackrel{\‾}{N}}_2=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}P\left(K\right)\underset{m=0}{\overset{K}{\mathrm{\Σ}}}\underset{n=0}{\overset{J-K}{\mathrm{\Σ}}}{\mathrm{mP}}_{\det \mathrm{ect}}(m,n)=J(1-\mathrm{Pe})P_D---\left(12\right)$

Potential throughput under the situation 2 is expressed as

${\mathrm{PTP}}_2=\frac{{\stackrel{\‾}{N}}_2}{\stackrel{\‾}{L}}---\left(13\right)$

Take into account above-mentioned two kinds of situations, potential throughput is expressed as

PTP＝δ·PTP ₁+(1-δ)·PTP ₂(14)

Wherein, δ is a constant, 0≤δ≤1;

Selecting initial value δ, is objective function optimization detector thresholding with potential throughput, order

$\frac{\mathrm{dPTP}}{{\mathrm{dP}}_F}=0---\left(15\right)$

Can get

$\frac{{\mathrm{dP}}_D}{{\mathrm{dP}}_F}=\frac{\mathrm{\δ}(J-1)\mathrm{Pe}{P}_D{I_2}^{J-2}(J-{\mathrm{JI}}_1+{I_1}^J)+\mathrm{JPe}{P}_D(1-{I_1}^{J-1})[{{\mathrm{\δI}}_2}^{J-1}+(1-\mathrm{\δ})]}{[\mathrm{\δ}{I_2}^{J-2}{I}_3+(1-\mathrm{\δ})](J-{\mathrm{JI}}_1+{I_1}^J)-J(1-\mathrm{Pe})P_D(1-{I_1}^{J-1})[{{\mathrm{\δI}}_2}^{J-1}+(1-\mathrm{\δ})]}---\left(16\right)$

Wherein, I ₁=(1-Pe) (1-P _D)+Pe (1-P _F), I ₂=(1-Pe) P _D+ Pe (1-P _F), I ₃=Pe (1-P _F)+JP _D(1-Pe).

Under the high s/n ratio situation, P _D≈ 1, P _F≈ 0, (1-P _F)/P _D≈ 1, and formula (16) is reduced to:

$\frac{{\mathrm{dP}}_D}{{\mathrm{dP}}_F}=\frac{\mathrm{\δ}(J-1)\mathrm{Pe}(J-\mathrm{JPe}+{\mathrm{Pe}}^J)+\mathrm{JPe}(1-{\mathrm{Pe}}^{J-1})}{\left\{\mathrm{\δ}\right[\mathrm{Pe}+J(1-\mathrm{Pe})]+(1-\mathrm{\δ})\}(J-\mathrm{JPe}+{\mathrm{Pe}}^J)-J(1-\mathrm{Pe})(1-{\mathrm{Pe}}^{J-1})}=\mathrm{\β}---\left(17\right)$

From formula (3) and formula (4), can get:

$P_D={P_F}^{1/1+\mathrm{SNR}},\mathrm{SNR}=\frac{{\mathrm{\σ}}_A^2}{{\mathrm{\σ}}_v^2}---\left(18\right)$

$\frac{{\mathrm{dP}}_D}{{\mathrm{dP}}_F}=\frac{1}{1+\mathrm{SNR}}{P_F}^{-\mathrm{SNR}/(1+\mathrm{SNR})}---\left(19\right)$

From formula (18) and formula (19), can get:

P _F，opt＝[(1+SNR)β] ^-(1+SNR)/SNR (20)

Can get the detector thresholding according to formula (3) and formula (20) is:

$T_{\mathrm{opt}}=\sqrt{{-2\mathrm{\σ}}_v^2\log \left[P_{F,\mathrm{opt}}\right]}=\sqrt{{2\mathrm{\σ}}_v^2\frac{1+\mathrm{SNR}}{\mathrm{SNR}}\log \left[(1+\mathrm{SNR})\mathrm{\β}\right]}---\left(21\right);$

(2) after information source sends packet, destination carries out collision detection according to the detector thresholding of trying to achieve to receiving packet, in case conflict is detected, destination will be adjudicated conflict exponent number and active user collection, by control channel court verdict will be notified to the all-network user then;

(3) be the linearity that obtains collision signal duplicate independently, system enters the auxiliary retransmission time period of relaying, the conflict exponent number that the length of retransmission time period equals to be detected subtracts 1, a node is elected to be relaying randomly and is retransmitted the signal that it receives at the conflict time slot, the auxiliary retransmission time period one of relaying finishes, the broadcast channel control bit of just resetting is ended current re-transmission and transmission that all are relevant;

(4) destination all colliding data bags of utilizing the linear solution butt joint of suboptimum to receive are united and are unpacked, and realize that many bags separate.When conflict exponent number K and active user collection When correctly being detected,

And

Make the transmission signal indication of source node be

Make the received signal of destination be expressed as

, wherein Then the matrix form of received signal is expressed as Z=HX+W, and wherein, H represents channel coefficients between source node and destination, can detect by active user to obtain estimating that W represents noise matrix.When many bags separate, when the channel matrix full rank, can utilize the separation of the linear solution realization of suboptimum colliding data bag, promptly

And obtain the real-time network goodput ATP corresponding with initial value δ;

(5) result of above-mentioned steps (4) is exported to the renewal of coefficient δ, its process is the iteration to coefficient δ different values in the scope of 0≤δ≤1 in the formula (14), repeating step (1)-(4) finally obtain the goodput ATP of formula (21) result for the network of optimum detector thresholding and correspondence.

In the above-mentioned steps (3): make arbitrary node i in the network that (1≤i≤J) packet in conflict time slot n transmission is expressed as x _i(n)=[x _{I, 0}(n) ... x _{I, M-1}(n)], each packet comprises M symbol, and the transmitted power of each symbol is σ _x ²The signal indication that destination received signal and all idle node (user that the conflict time slot is not given out a contract for a project) receive is

Time slot n+k, A node is chosen as relaying at random, and retransmits it at the signal y (n) of time slot that conflicts.At this moment, destination place received signal is expressed as

(23)

Wherein Be the via node set; a _Rd(n) be channel coefficients between r via node and destination; w _d(n+k) be noise vector; C (n+k) is a normalization coefficient.If

Be that relaying itself is not a source node, y (n)=y then _r(n),

Wherein

If

Be that relaying itself is exactly a source node, y (n)=x then _r(n), c (n+k)=1.

When above-mentioned optimum detector thresholding obtained, the iteration selection course of coefficient δ was as follows in the formula (14):

(1) initial value of coefficient δ is made as 0, at this moment PTP=PTP ₂

(2) try to achieve corresponding thresholding and realization conflict separation, more real-time goodput ATP and potential throughput, calculate | PTP-ATP| ²

(3) update coefficients δ makes δ=δ+Δ δ, and wherein above-mentioned steps (2) is repeated in Δ δ=1/J and 0≤δ≤1;

(4) repeat above-mentioned steps (2), (3), find to make real-time goodput and the most approaching coefficient δ of potential throughput, promptly satisfy

The time, formula (21) result is the optimum detector thresholding.

Advantage of the present invention and remarkable result: the present invention introduces collision detection in the auxiliary many packet receivers system of relaying, has broken the hypothesis that the conflict exponent number can correctly be detected in existing NDMA and the ALLIANCES mechanism.Desirable collision detection and imperfect conflict check system Effect on Performance have been taken all factors into consideration in the mathematical analysis of systematic function-potential throughput, and worst case and best-case when having taken into account potential throughput evaluation, thereby be a kind of systematic function estimation of more realistic signal intelligence, can obtain more accurate optimum detector thresholding in view of the above, and then obtain than NDMA mechanism and the better throughput performance of time slot A LOHA mechanism.

Description of drawings:

Fig. 1 is the flow chart of the inventive method;

Fig. 2 is that three users' colliding data bag retransmits schematic diagram.

Embodiment

The invention will be further described below in conjunction with drawings and Examples.

Referring to Fig. 1,2, the detector thresholding determine to comprise two steps: the 1. mathematical analysis of potential throughput: utilize potential throughput on the conflict time slot to substitute throughput and predict throughput performance on the whole transmission period, defining potential throughput and be can successful data recovered bag in the potential unit time slot.The probability of giving out a contract for a project, detection probability and false alarm probability according to network user's number, user are predicted the potential throughput of network, specifically predict in two kinds of situation, and the throughput of predicting under two kinds of situations is carried out linear combination.2. the selection of detector thresholding: obtain derivative relation between detection probability and false alarm probability by asking the extreme value computing, and then try to achieve the detector thresholding according to the functional relation between detection probability and the false alarm probability.

The transmission of colliding data bag: K of supposition wraps in time slot n and clashes, order

The court verdict of expression conflict exponent number K,

The expression active user collection user's collection that promptly conflicts

Court verdict.At the destination court verdict

With

Down, for recovering

Individual colliding data bag, the auxiliary retransmission time period length of relaying is fixed as

Individual time slot.At time slot n+k,

A node is selected as relaying, if this node is non-information source relaying, then retransmits the collision signal that it receives at the conflict time slot; If this node is the information source relaying, then retransmit the packet that it produces at the conflict time slot.

The separation of colliding data bag: the packet that will receive on receiving terminal will conflict packet that time slot receives and the auxiliary retransmission time period of relaying carries out combined decoding.Channel coefficient matrix can detect by active user and obtain estimating.When the channel matrix full rank, can utilize the linear solution of suboptimum to realize the separation of colliding data bag.

Iteration according to coefficient δ in the formula (14) is selected, and finds to make real-time goodput and the most approaching coefficient δ of potential throughput in the scope of 0≤δ≤1, promptly satisfies

The time, be the optimum detector thresholding, with the detector thresholding of the square frame 1 among optimum detector thresholding replacement Fig. 1, proceed follow-up square frame step by Fig. 1 then, realize best many bags separating effect at last.

Claims (3)

1. select based on the detector thresholding of collision detection and cooperation conflict separation method, it is characterized in that:

(1) at first, count J, user's the probability of giving out a contract for a project, detection probability and false alarm probability predicts the potential throughput of network according to the network user, by asking the extreme value computing to obtain derivative relation between detection probability and false alarm probability, and then try to achieve the detector thresholding, step is as follows:

To be user buffer be empty probability zero hour period in transmission to definition Pe, when K user when conflicting time slot collision, its binary expression is as follows:

$\begin{array}{cc}P\left(K\right)=\left(\begin{array}{c}J\\ K\end{array}\right){(1-\mathrm{Pe})}^K{\mathrm{Pe}}^{J-K}& K=\mathrm{0,1},...,J---\left(1\right)\end{array}$

Wireless channel is modeled as the Rayleigh flat fading channel

Wherein, phase place

[0,2 π) go up and obey evenly distribution; Amplitude A _Ij(n) Rayleigh distributed, variance are 2 σ _A ²A _Ij(n) and

Separate, channel is obeyed independent same distribution, noise w between all users _r(n) be modeled as the white gaussian variable of incoherent return-to-zero average, variance is σ _v ²

False alarm probability P _FBe expressed as:

$P_F={\∫}_T^{\∞}\frac{x}{{\mathrm{\σ}}_v^2}\exp (-\frac{x^2}{2{\mathrm{\σ}}_v^2})\mathrm{dx}=\exp (-\frac{T_2}{2{\mathrm{\σ}}_v^2})---\left(3\right)$

Detection probability P _DBe expressed as:

$P_D={\∫}_T^{\∞}\frac{x}{{\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2}\exp (-\frac{x^2}{2({\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2)})\mathrm{dx}=\exp (-\frac{T^2}{2({\mathrm{\σ}}_v^2+{\mathrm{\σ}}_A^2)})---\left(4\right)$

Making m represent can be by the quantity of correct detected information source node, and n represents by false-alarm to be the idle node quantity of active node, correspondingly, and the conflict exponent number that is detected

Equal m+n.When K-m information source omission, n free subscriber by the probability of false-alarm is:

$P_{\det \mathrm{ect}}(m,n)=\left(\begin{array}{c}K\\ m\end{array}\right){\left(P_D\right)}^m{(1-P_D)}^{K-m}\left(\begin{array}{c}J-K\\ n\end{array}\right){\left(P_F\right)}^n{(1-P_F)}^{J-K-n}---\left(5\right)$

Wherein, 0≤m≤K, 0≤n≤J-K.Therefore, all correct probability that detects promptly correctly detects all active users (m=K), and no free subscriber is shown by the probability tables of false-alarm (n=0):

P _detect(K，0)＝P _D ^K(1-P _F) ^J-K (6)

Correspondingly, the lengths table of transmission period is shown:

$L(K,m,n)=\left\{\begin{array}{cc}m+n,& 0\≤m\≤K,0\≤n\≤J-K,m+n\≠0\\ 1,& m=0\mathrm{andn}=0\end{array}\right.---\left(7\right)$

When K information source conflict, the average length of transmission period is expressed as:

$\stackrel{\‾}{L}\left(K\right)=\underset{m=0}{\overset{K}{\mathrm{\Σ}}}\underset{n=0}{\overset{J-K}{\mathrm{\Σ}}}{P}_{\det \mathrm{ect}}(m,n)L(K,m,n)=K{P}_D+(J-K)P_F+{(1-P_D)}^K{(1-P_F)}^{J-K}---\left(8\right)$

The average length of transmission period is expressed as:

$\stackrel{\‾}{L}=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}P\left(K\right)\stackrel{\‾}{L}\left(K\right)=J{P}_F+J(1-\mathrm{Pe})(P_D-P_F)+{[(1-\mathrm{Pe})(1-P_D)+\mathrm{Pe}(1-P_F)]}^J---\left(9\right)$

The assessment of potential throughput has two kinds of situations:

A) situation 1: when potential throughput is assessed, each mistaken verdict of hypothesis goal end all will cause transmitting losing of last all packets of period, therefore, only when destination is made right-on judgement, the transmission period is only useful, on the useful transmission period, K packet can correctly be recovered at most.At this moment, average potential recoverable bag is expressed as:

${\stackrel{\‾}{N}}_1=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}\mathrm{KP}\left(K\right)P_{\det \mathrm{ect}}(K,0)=J(1-\mathrm{Pe})P_D{[(1-\mathrm{Pe})P_D+\mathrm{Pe}(1-P_F)]}^{J-1}---\left(10\right)$

Potential throughput under the situation 1 is expressed as

${\mathrm{PTP}}_1=\frac{{\stackrel{\‾}{N}}_1}{\stackrel{\‾}{L}}---\left(11\right)$

B) situation 2: under this hypothesis, under the situation of destination mistake in judgment, still have some conflicting data bag fortunately to be detected.When K-m information source omission, there be m information source correctly to recover at the most.At this moment, average potential recoverable bag is expressed as

${\stackrel{\‾}{N}}_2=\underset{K=0}{\overset{J}{\mathrm{\Σ}}}P\left(K\right)\underset{m=0}{\overset{K}{\mathrm{\Σ}}}\underset{n=0}{\overset{J-K}{\mathrm{\Σ}}}m{P}_{\det \mathrm{ect}}(m,n)=J(1-\mathrm{Pe})P_D---\left(12\right)$

Potential throughput under the situation 2 is expressed as

${\mathrm{PTP}}_2=\frac{{\stackrel{\‾}{N}}_2}{\stackrel{\‾}{L}}---\left(13\right)$

Take into account above-mentioned two kinds of situations, potential throughput is expressed as

PTP＝δ·PTPd ₁(1-δ)·PTP ₂ (14)

Wherein, δ is a constant, 0≤δ≤1;

Selecting initial value δ, is objective function optimization detector thresholding with potential throughput, order

$\frac{\mathrm{dPTP}}{d{P}_F}=0---\left(15\right)$

Can get

$\frac{{\mathrm{dP}}_D}{{\mathrm{dP}}_F}=\frac{\mathrm{\δ}(J-1){\mathrm{PeP}}_D{I}_2^{J-2}(J-J{I}_1+I_1^J)+\mathrm{JPe}{P}_D(1-I_1^{J-1})[\mathrm{\δ}{I}_2^{J-1}+(1-\mathrm{\δ})]}{[\mathrm{\δ}{I}_2^{J-2}{I}_3+(1-\mathrm{\δ})](J-J{I}_1+I_1^J)-J(1-\mathrm{Pe})P_D(1-I_1^{J-1})[\mathrm{\δ}{I}_2^{J-1}+(1-\mathrm{\δ})]}---\left(16\right)$

Wherein, I ₁=(1-Pe) (1-I _D)+Pe (1-P _F), I ₂=(1-Pe) P _D+ Pe (1-P _F), I ₃=Pe (1-P _F)+JP _D(1-Pe).

Under the high s/n ratio situation, P _D≈ 1, P _F≈ 0, (1-P _F)/P _D≈ 1, and formula (16) is reduced to:

$\frac{d{P}_D}{d{P}_F}=\frac{\mathrm{\δ}(J-1)\mathrm{Pe}(J-\mathrm{JPe}+{\mathrm{Pe}}^J)+\mathrm{JPe}(1-{\mathrm{Pe}}^{J-1})}{\left\{\mathrm{\δ}\right[\mathrm{Pe}+J(1-\mathrm{Pe})]+(1-\mathrm{\δ})\}(J-\mathrm{JPe}+{\mathrm{Pe}}^J)-J(1-\mathrm{Pe})(1-{\mathrm{Pe}}^{J-1})}=\mathrm{\β}---\left(17\right)$

From formula (3) and formula (4), can get:

P _D＝P _F ^1/1+SNR， $\mathrm{SNR}=\frac{{\mathrm{\σ}}_A^2}{{\mathrm{\σ}}_v^2}---\left(18\right)$

$\frac{d{P}_D}{d{P}_F}=\frac{1}{1+\mathrm{SNR}}{P}_F^{-\mathrm{SNR}/(1+\mathrm{SNR})}---\left(19\right)$

From formula (18) and formula (19), can get:

P _F，opt＝[(1+SNR)β] ^-(1+SNR)/SNR (20)

Can get the detector thresholding according to formula (3) and formula (20) is:

$T_{\mathrm{opt}}=\sqrt{-2{\mathrm{\σ}}_v^2\log \left[P_{F,\mathrm{opt}}\right]}=\sqrt{2{\mathrm{\σ}}_v^2\frac{1+\mathrm{SNR}}{\mathrm{SNR}}\log \left[(1+\mathrm{SNR})\mathrm{\β}\right]}---\left(21\right);$

(2) after information source sends packet, destination carries out collision detection according to the detector thresholding of trying to achieve to receiving packet, in case conflict is detected, destination will be adjudicated conflict exponent number and active user collection, by control channel court verdict will be notified to the all-network user then;

(3) be the linearity that obtains collision signal duplicate independently, system enters the auxiliary retransmission time period of relaying, the conflict exponent number that the length of retransmission time period equals to be detected subtracts 1, a node is elected to be relaying randomly and is retransmitted the signal that it receives at the conflict time slot, the auxiliary retransmission time period one of relaying finishes, the broadcast channel control bit of just resetting is ended current re-transmission and transmission that all are relevant;

(4) when the channel matrix H full rank, all colliding data bags that destination can utilize the linear solution butt joint of suboptimum to receive are united and are unpacked,

Realize that many bags separate, and obtain the real-time network goodput ATP corresponding with initial value δ;

(5) result of above-mentioned steps (4) is exported to the renewal of coefficient δ, its process is the iteration to coefficient δ different values in the scope of 0≤δ≤1 in the formula (14), repeating step (1)-(4) finally obtain the goodput ATP of formula (21) result for the network of optimum detector thresholding and correspondence.

2. the detector thresholding based on collision detection according to claim 1 is selected and cooperation conflict separation method, it is characterized in that: (1≤i≤J) packet in conflict time slot n transmission is expressed as x for the arbitrary node i in the network _i(n)=[x _{I, 0}(n) ... x _{I, M-1}(n)], each packet comprises M symbol, and the transmitted power of each symbol is σ _x ²The signal indication that destination received signal and all idle node (user that the conflict time slot is not given out a contract for a project) receive is

$y_r\left(n\right)=\underset{i\∈S\left(n\right)}{\mathrm{\Σ}}{a}_{\mathrm{ir}}\left(n\right)x_i\left(n\right)+w_r\left(n\right),$

Time slot n+k,

A node is chosen as relaying at random, and retransmits it at the signal y (n) of time slot that conflicts.At this moment, destination place received signal is expressed as

$z_d(n+k)=a_{\mathrm{rd}}(n+k)c(n+k)y\left(n\right)+w_d(n+k),$

Wherein

Be the via node set; a _Rd(n) be channel coefficients between r via node and destination; w _d(n+k) be noise vector; C (n+k) is a normalization coefficient.If

Be that relaying itself is not a source node, y (n)=y then _r(n),

Wherein

If

Be that relaying itself is exactly a source node, y (n)=x then _r(n), c (n+k)=1.

3. select and cooperation conflict separation method according to claim 1 and 2 described detector thresholdings based on collision detection, when it is characterized in that the optimum detector thresholding obtains, the iterative process of coefficient δ is as follows in the formula (14):

(1) initial value of coefficient δ is made as 0, at this moment PTP=PTP ₂

(2) try to achieve corresponding thresholding and realization conflict separation, more real-time goodput ATP and potential throughput, calculate | PTP-ATP| ²

(3) update coefficients δ makes δ=δ+Δ δ, and wherein above-mentioned steps (2) is repeated in Δ δ=1/J and 0≤δ≤1;

(4) repeat above-mentioned steps (2), (3), find to make real-time goodput and the most approaching coefficient δ of potential throughput, promptly satisfy

The time, formula (21) result is the optimum detector thresholding.

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