CN101471705B - Sensing network node terminal with environmental suitability automatic gain adjustment - Google Patents

Abstract

The invention provides a sensor network node terminal with the functions of environmental adaptation and automatic gain control. In the sensor network node terminal, an information transmitting device of the sensor network node terminal determines the required current spread spectrum factor via a spread spectrum mode decision module; a frame-header spread spectrum processing module determines the captured frame header according to the current spread spectrum factor; simultaneously an information processing module performs the spreading and other treatments of the communication information required for transmission according to the current spread spectrum factor to form the spread spectrum information; further a merging module merges the captured frame header and the spread spectrum information and then transmits the merged product after the shaping filtration and the radio frequency modulation; an information receiving device converts the frequency of the received radio-frequency signal; related modules further process the radio-frequency signal; a spread spectrum gain determining module despreads the related signals and then determines the spread spectrum gain factor required for the node terminal that transmits the radio-frequency signal; an information resolving module resolves the received information according to the determined spread spectrum gain factor; and a spread spectrum gain correcting module corrects the spread spectrum gain factor and then transmits the corrected spread spectrum gain factor to the spread spectrum mode decision module; thereby achieving the coarse adjustment of gain.

Description

Sensing network node terminal with the adjustment of environmental suitability automatic gain

Technical field

The present invention relates to the spread spectrum radio communication in a kind of wireless sense network, particularly a kind of sensing network node terminal with the adjustment of environmental suitability automatic gain.

Background technology

Wireless sensor network (Wireless Sensor Network; WSN) relate to multidisciplinary height intersection, the integrated hot research field, forward position of knowledge height; It combines sensor technology, embedding people formula computing technique, modern network and wireless communication technology, distributed information processing etc.; Can be through the information of all kinds of integrated microsensors cooperation ground monitorings in real time, perception and various environment of collection or monitoring target; These information are sent out through wireless mode, and are sent to user terminal with the network mode of organizing multi-hop certainly, thereby realize physical world, the connection of calculating the world and the human society ternary world.Sensor network has very wide application prospect; At many key areas such as military and national defense, industrial or agricultural, city management, biologic medical, environmental monitoring, rescue and relief work, anti-probably anti-terrorism, deathtrap Long-distance Control potential practical value is arranged all; Cause the great attention of many national academias and industrial quarters, be considered to one of technology of power that 21 century had an immense impact on.

Yet there are four big limited problems in wireless sense network, and promptly energy is limited, communication capacity is limited, calculating and storage capacity are limited, and wherein, energy constraint is its most basic problem, when designing, need take into full account.And the wireless transmission energy consumption is mainly derived from the energy consumption of wireless module when transceive data and idle intercepting.Usually, in network operation process, wireless module possibly be in four kinds of states: transmission, reception, idle and sleep, the energy consumption under these four kinds of states is different.See also Fig. 1, it is the comparison diagram of several kinds of energy consumptions in the wireless sensor network, and this energy consumption comparison diagram is primarily aimed in wireless sensor network short-distance transmission (promptly 10 meters to 100 meters) scene, and sending energy consumption under this scene is analogous with receiving energy consumption.Visible by figure; The energy consumption of wireless module is originated and become main energy consumption, especially when wireless module is in idle condition considerably beyond sensing module and processing module; Its energy consumption is the energy consumption of accepting state no better than; Therefore, in order effectively to save energy, should make wireless module be in sleep state as far as possible.

See also Fig. 2, it is the electrical block diagram of wireless module, and it mainly comprises transtation mission circuit, power amplifier and receiving circuit etc., is E if the total power consumption of a bit is sent in definition _b, E then _bSatisfy formula: $E_b=E_{\mathrm{Elec}}^{\mathrm{Tx}}+E_{\mathrm{RF}}+E_{\mathrm{Elec}}^{\mathrm{Rx}},$ Wherein, E _Elec ^TxBe the energy consumption of transtation mission circuit, E _RFBe the energy consumption of power amplifier, E _Elec ^RxEnergy consumption for receiving circuit; If transmission speed is fast, the time T of a bit of transmission _bMore little, corresponding transtation mission circuit and receiving circuit energy consumption E _Elec ^Tx, E _Elec ^TxThen more little, but the bit error rate performance in order to guarantee to expect, the power amplifier transmitting power is big more, corresponding energy consumption E _RFJust big more.See also Fig. 3, it is E _RFWith transmission time T _bVariation diagram, obviously, T _bBig more, E _RFJust more little.See also Fig. 4 again, it is E _Elec ^TxAnd E _Elec ^RxWith transmission time T _bVariation diagram, obviously, T _bBig more, E _Elec ^TxAnd E _Elec ^RxJust big more.Therefore, if transtation mission circuit and receiving circuit energy consumption much smaller than the energy consumption of power amplifier, are then transmitted the total energy consumption E of a bit _bWith transmission time T _bElongated and be tending towards descending.If transtation mission circuit and receiving circuit energy consumption are suitable with the power amplifier energy consumption, then E _bWith transmission time T _bChange and to be tending towards the opening parabola that makes progress, as shown in Figure 5, therefore,, all there is the transmission time T of an optimum no matter for long haul communication or short haul connection _bMake E _bMinimum.Therefore, for each node of sensing net, always can there be the transmission time T of an optimum _bSo that it is energy consumption minimized.

, because the laying mode of sensing net random scatter causes each inter-node communication distance and environment to be not quite similar.For same communication equipment, under different environments for use, because there is difference in channel situation, so cause its maximum transmission rate under fixing bit error probability situation to have nothing in common with each other.Especially to channel circumstance complicated and changeable, need to be treated differently especially.For example; With the channel under the difference ring border is target design coding and modulation technique, then will increase in the system much to be used for overcoming the expense of poor condition, and under the good situation of channel condition; These expenses are unnecessary, so will reduce the efficiency of transmission of system greatly.Therefore,, under the situation of bad channel conditions, can reduce transmission rate, or increase transmitting power, overcome the expense of poor condition for the sensing net; And under the good situation of channel condition, can improve information transfer efficiency and transmission rate, or reduce transmitting power, to reduce system energy consumption, promptly need a kind of adaptive communications control.

Because adaptive communications control and power control have the comparable part, therefore typical power control mode are done a simple declaration.In existing power control mode, can be divided into inner loop power control and exterior ring power control by the source of performance number, can be divided into uplink power control and descending power is controlled by the control direction.Wherein, the main effect of inner loop power control is that (Signal Interfence Rate SIR) converges on the target SIR value to make received signal to noise ratio through the transmitting power of control physical channel.Inner loop power control can be divided into open loop and closed loop dual mode, and the purpose of open Loop Power control provides the rough estimate of transmitting power, according to measurement result path loss and interference level are estimated, thus the process of calculating Initial Trans.Closed power control is that the uplink and downlink link to communication period carries out the fast power adjustment, so that the quality of link converges on the target SIR value; Exterior ring power control is through dynamically adjusting the sir target value of inner loop power control; Communication quality is met the demands all the time; Promptly reach FER (the Frame Error Rate of regulation; FER)/and Block Error Rate (Block Error Rate, BLER)/bit error rate (Bit Error Rate, BER) value; Uplink power control makes the base station receive that all travelling carriages are transmitted into signal of base station power or SIR is equal basically through the transmitting power of control mobile station UE; Descending power control is used for controlling the transmitting power of base station, and signal power or SIR that all travelling carriages are received are suitable basically.

From the above mentioned; In sensing net system,, can avoid sending unnecessary excessive power through control to power or transmission rate; Effectively practice thrift the entire system energy consumption, and when being necessary to carry out multi-user communication, can guarantee to arrive the watt level unanimity of receiving terminal basically.Although power control is technological means common in the Resistant DS Spread Spectrum System; In cdma system; Be mainly used in each user's of control transmitted power, make its signal that arrives receiving terminal have identical power, or be used to control the transmission signal of base station end; The signal power that makes it arrive receiving terminal is just right, realizes the efficiency maximization.But when being incorporated into the control of the power in the cdma system in the sensing net system, run into following problem:

1, the prerequisite of power control is that the energy size is analyzed, and carries out the measurement of SIR, in the WCDMA system, through pilot channel estimation is carried out sir measurement, but in the sensing net system of asynchronous communication, does not exist to be used for synchronous pilot channel;

2, power control is divided into two kinds of closed power control and open Loop Power control, and two kinds of controls all need the adjustment of protocol layer, make power reach optimization through receiving-transmitting sides adjustment repeatedly.But in sensing net system, information is burst communication mostly, and too much protocol interaction will reduce system effectiveness greatly.

Therefore, how to realize in the sensing net that adaptive gain control has become the technical task that those skilled in the art need to be resolved hurrily in fact.

Summary of the invention

The object of the present invention is to provide a kind of sensing network node terminal that the environmental suitability automatic gain is adjusted that has, increase the rough adjustment to gaining under the situation that does not seldom also need simultaneously the agreement intervention to be implemented in system cost.

In order to achieve the above object; Sensing network node terminal with the adjustment of environmental suitability automatic gain provided by the invention; Comprise information receiver and information transmitting apparatus; Wherein, said information transmitting apparatus comprises: the spread spectrum mode decision-making module of the current spreading factor that the definite signal of communication of launching to said first node end of the RST that a first node end is sent in the sensing net that is used for receiving according to said information receiver, said information transmitting apparatus present located role and state need adopt; Be used for according to determined current spreading factor and last time confirming the coding of current frame head, and the spreading gain that employing and said first node end are made an appointment carries out spread spectrum to form the frame head spread processing module of respective capture frame head to determined frame head to the transmit spreading factor that adopted of said first node end; Be used for the transferred communication information being carried out chnnel coding, serial to parallel conversion and spread processing to form corresponding spread spectrum information according to determined current spreading factor; It is provided with a spread spectrum parameter control unit, is used for according to determined current spreading factor control channel coding, serial to parallel conversion and is applied to relevant each parameter of pseudo noise code of spread spectrum mutually so that the bandwidth of the spread spectrum information that produces meets the message processing module of preset requirement; Be used for catching the merging module that frame head makes an addition to said spread spectrum information with formed; Be used for to be added with the molding filtration module of the spread spectrum information molding filtration of catching frame head; The radio-frequency module of launching after the information via rf modulations that is used for the molding filtration module is exported; Said information receiver comprises: be used for the radiofrequency signal that transmits at the sensing net is received the frequency-variable module that the back frequency conversion forms intermediate-freuqncy signal; Be used for said intermediate-freuqncy signal and the local pseudo noise code that is produced are carried out relevant back to obtain the correlation module of corresponding coherent signal; Be used for that said coherent signal is carried out the corresponding information despreading and handle the back obtaining corresponding frame head, and confirm to send the spreading gain determination module of the spreading gain factor that node side adopted of said radiofrequency signal according to the information that said frame head carries; Be used for said coherent signal is analyzed to estimate corresponding received signal power and noise; And the determined spreading gain factor of said spreading gain determination module is revised so that the revised spreading gain factor adapts to the current environment of said sensing net, and the revised spreading gain factor is sent to the spreading gain correcting module of said spread spectrum mode decision-making module with the RST that is sent to as respective nodes end in the sensing net that said information receiver was received according to said received signal power and noise; Be used for comprising that according to the said intermediate-freuqncy signal of the determined spreading gain factor pair of said spreading gain determination module separating the each item that extends to channel-decoding handles to obtain the entrained communication information of said quite signal; It is provided with a despreading control unit, is used for according to the gain of the determined spreading gain FACTOR CONTROL of said spreading gain determination module information despreading and confirms that the information of the original position of the said communication information resolves module.

Preferable, said spread spectrum mode decision-making module is according to G _P2+ G _S2>=G ₀+ G _S1+ Δ S _InNeed to confirm the current spreading factor of employing, wherein, G _P2Be the current spreading factor that need adopt, G _S2Be the transmitting power that adopts, G ₀For the revised said first node end that is sent to by said spreading gain correcting module transmits the spreading factor that signal adopts, G _S1Be the transmitting power that said first node end adopts, Δ S _InBe the maximum difference of corresponding each the node side device sensitivity of sensing net, in addition, said spread spectrum mode decision-making module also is provided with map unit, is used for as determined current spreading factor G _P2To its mapping that makes progress, promptly work as determined current spreading factor G when not existing _P2Be in [2 ^N-1-1,2 ^N-1] in the time of between, makes the current spreading factor G after the mapping ^P2Be 2 ^N-1.

Preferable; Transmitted the spreading factor that adopted not simultaneously when determined current spreading factor and last time to said first node end, and the determined present frame header encoder of said frame head spread processing module is complete 1 the combination of catching position and said current spreading factor; Transmitted the spreading factor that adopted when identical when determined current spreading factor and last time to said first node end; The determined present frame header encoder of said frame head spread processing module is merely complete 0 the position of catching; In addition; Said frame head spread processing module adopts fixing long code to carry out spread processing, and said spreading gain of making an appointment is maximum spreading gain.

Preferable, said spreading gain correcting module comprises: be used for basis $P_s=\frac{\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\mathrm{Max}\[R(k,m)\]}{K}$ The received signal power evaluation unit of estimating received signal power, wherein, P _sBe received signal power, $R(k,m)=\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)}$ K=0,1,2 ..., R _I(k, m) and R _Q(k m) is coherent signal; And be used for basis $P_n=\frac{\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{\underset{m\∉N}{m=1}}{\overset{T}{\mathrm{\Σ}}}{R}_{\mathrm{Noise}}(k,m)}{K(T-2D-1)}$ The noise estimation unit of estimated noise, wherein, P _nBe noise, $R_{\mathrm{Noise}}(k,m)=\stackrel{\‾}{R}(k,m)-{\stackrel{\‾}{R}}_{\mathrm{Ref}}(k,m),$ And

$\stackrel{\‾}{R}(k,m)=\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)}/\max \left(\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)}\right),$

${\stackrel{\‾}{R}}_{\mathrm{Ref}}(k,m)=R_{\mathrm{Ref}}(k,m)/\mathrm{Max}\left(R_{\mathrm{Ref}}(k,m)\right),$ R _Ref(k m) is local relevant code word and the result who self carries out after relevant, N=[n-n _p-D, n-n _p+ D], and D counts for the correlation peak that needs to remove, therefore, the revised spreading gain factor of said spreading gain correcting module can be: $\frac{\mathrm{SIR}}{{\mathrm{SIR}}_{\mathrm{Spec}}}=\frac{G_c}{G_{\mathrm{Spec}}},$ Wherein, G _cBe the determined spreading gain factor of said spreading gain determination module, G _SpecBe the revised spreading gain factor, SIR=P _s/ P _n, SIR _SpecBe the target signal to noise ratio.

In sum; Sensing network node terminal with environmental suitability automatic gain adjustment of the present invention is through handling and carry out SIR and estimate carrying out quadratic sum after pilot header relevant; And the transmitting power that estimates confirm need increase through SIR or carry out the adjustment of spreading gain, in said adjustment, owing to require as long as satisfy transmission range basically; Not high to the accuracy requirement of measuring and adjust; Therefore can simplify the design of protocol layer, through to maybe situation estimate simply to adjust and get final product in physical layer, thereby can reduce the complexity and the overhead on this problem of protocol layer.

Description of drawings

Fig. 1 is the existing energy consumption comparison diagram of wireless module under different conditions.

Fig. 2 is existing wireless module electrical block diagram.

Fig. 3 for the energy consumption of the power amplifier of existing wireless module with transmission time Tb variation diagram.

Fig. 4 for the energy consumption of the transtation mission circuit of existing wireless module and receiving circuit with transmission time Tb variation diagram.

Total power consumption and transmission time graph of a relation when Fig. 5 is existing wireless module short distance and long haul communication.

Fig. 6 is the information transmitting apparatus structural representation with sensing network node terminal of environmental suitability automatic gain adjustment of the present invention.

Fig. 7 is the physical layer frame form that information transmitting apparatus adopted with sensing network node terminal of environmental suitability automatic gain adjustment of the present invention.

Fig. 8 is the information receiver structural representation with sensing network node terminal of environmental suitability automatic gain adjustment of the present invention.

Fig. 9 when the emulation SNR=-20dB signal correlation values with estimate correlation and relatively illustrate picture group.

Figure 10 when the emulation SNR=-40dB signal correlation values with estimate correlation and relatively illustrate picture group.

Figure 11 estimates correlation peak/correlated noise and signal to noise ratio graph of a relation under the correlation mode for removing.

Figure 12 is not for removing correlation peak/correlated noise and signal to noise ratio graph of a relation under the preparatory correlation mode.

Figure 13 is for removing preparatory correlation mode and not removing preparatory correlation mode and amplify comparison diagram.

Figure 14 is the influence sketch map of frequency shift (FS) to SIR.

Figure 15 has the comparison diagram of frequency deviation and no frequency deviation during for SNR=-40dB.

Figure 16 has the comparison diagram of frequency deviation and no frequency deviation during for SNR=-20dB.

Transmission usefulness comparison diagram when Figure 17 changes the factor for not transmitting spreading gain.

Transmission usefulness comparison diagram when Figure 18 changes the factor for needing the transmission spreading gain.

Figure 19 is the transmission time comparison diagram.

Figure 20 is the path loss probability sketch map of random scatter node side.

Embodiment

The basic thought of the sensing network node terminal with environmental suitability automatic gain adjustment of the present invention is following:

The frame head that

sends through information carries out basic energy identification, adjusts foundation with this as basic spreading gain;

the physical layer energy situation that receives the frame head of signal capable of using is asked the sir value of calculating under the current state.In the asynchronous communication system, adopt the quadratic sum method to eliminate the influence of factors such as frequency deviation;

receiving terminal is as reference; Through basic correction, select spreading gain automatically;

with time information of receiving in view of the above ask calculate the spreading gain reference of sending as next time, and determine whether changing the spreading gain of next transmission information according to the scheduling situation of system;

, makes receiving terminal carry out parameter automatically despreading is set through to catching the setting of frame head form in physical layer.

From the above mentioned, said sensing network node terminal with the adjustment of environmental suitability automatic gain comprises information receiver and information transmitting apparatus.

See also Fig. 6, said information transmitting apparatus comprises spread spectrum mode decision-making module, frame head spread processing module, message processing module, merging module, molding filtration module and radio-frequency module.

The definite current spreading factor that need adopt of the RST that a first node end is sent in the sensing net that said spread spectrum mode decision-making module is used for receiving according to said information receiver, said information transmitting apparatus present located role and state to the signal of communication of said first node end emission; For example; When the first node end sends signal with spreading gain factor G; Under the constant situation of transmitting power, said information receiver can go out to satisfy the minimum spreading gain G of transmission requirement according to the calculated signals that receives ₀(concrete computational process is held the back statement), then said information transmitting apparatus can be according to said minimum spreading gain G ₀Estimate the spreading gain that self should adopt and adjust, so that when transmission next time information is given said first node end, adopt more excellent spreading gain, yet; Receive the signal of communication that the first node end is sent to from said information receiver, send the communication information to said first node end, exist the variation of time difference and possibility network configuration therebetween to said information transmitting apparatus; Therefore; Said spread spectrum mode decision-making module need be estimated the variable in distance between self and the said first node end, reserves sufficient surplus, because situation of change is unknown; For guaranteeing the connectedness of system, need change to increasing the system spread-spectrum gain direction.Therefore when being provided with, if the blanking time of this this transmission of message pick-up time gap last time is longer, the confidence level of correlation peak is low more, and the surplus that system need reserve is big more, specifies as follows:

Because the correlation peak of the signal of communication that said information receiver receives is relevant with the transmitting power and the sensitivity of self of said first node end, and it calculates the spreading gain factor G that obtains ₀Be the minimum spreading gain of said first node end, therefore, said spread spectrum mode decision-making module needs the influence of the sensitivity difference of consideration self transmitting power and said first node end when the spreading gain factor of self is set.Describe for knowing, define Several Parameters earlier, see also table 1:

Table 1

Symbol	Implication
		G S	Transmitting power
L	Propagation path loss
		S in	Radio-frequency sensitivity
G p	Spreading gain
		R D	Required transmission rate
H	The hidden requirement of signal

Have between the above-mentioned parameter: G _p+ G _s>=L-S _InAnd R _D=K/G _p, wherein, K is a constant, G _s＜H.When said first node end is sent to information, when said information receiver carries out information capture and calculates the spreading gain factor, have:

min(G _p1+G _s1)＝L-S _in2 (G ₀+G _s1)＝L-S _in2，

Minimum spreading gain/transmitting power G that said spread spectrum mode decision-making module need be adjusted _xRelation below existing:

G _x＝min(G _p2+G _s2)＝L-S _in1

If himself is Δ S with the worst error of said first node end equipment room sensitivity _In, i.e. Δ S _In>=| S _In1-S _In2|, G then _x=min (G _P2+ G _S2)≤G ₀+ G _S1+ Δ S _In, then get G thus _P2+ G _S2>=G ₀+ G _S1+ Δ S _InCan satisfy the system information transmissions requirement.Be that said spread spectrum mode decision-making module is according to G _P2+ G _S2>=G ₀+ G _S1+ Δ S _InNeed to confirm the current spreading factor of employing.

Yet as far as M sequence or Gold sequence, its sequence period is 2 ⁿ-1, n=1,2,3 ..., therefore said spread spectrum mode decision-making module is according to G _P2+ G _S2>=G ₀+ G _S1+ Δ S _InThe spreading gain G that confirms _P2Value might not exist, so said spread spectrum mode decision-making module also is provided with map unit, be used for as determined current spreading factor G _P2To its mapping that makes progress, promptly work as determined current spreading factor G when not existing _P2Be in [2 ^N-1-1,2 ^N-1] in the time of between, said map unit makes the current spreading factor G after the mapping _P2Be 2 ^N-1.

Said frame head spread processing module is used for according to determined current spreading factor and last time confirming the coding of current frame head to the transmit spreading factor that adopted of said first node end; And the spreading gain that employing and said first node end are made an appointment carries out spread spectrum to form the respective capture frame head to determined frame head; See also Fig. 7; It is for the physical layer frame form that the present invention adopted, as determined current spreading factor G _P2Transmitted the spreading factor G0 that adopted not simultaneously with last time to said first node end, and the determined present frame header encoder of said frame head spread processing module is complete 1 the combination of catching position and said current spreading factor; As determined current spreading factor G _P2Transmitted the spreading factor G0 that adopted when identical with last time to said first node end; The determined present frame header encoder of said frame head spread processing module is merely complete 0 the position of catching; This shows; Catch frame head and be complete 1 or complete 0, can be used for catching of the information of carrying out on the one hand, can be used for as whether the indication that need make amendment to the spreading gain factor on the other hand.When catching frame head is complete 1 the time; Expression needs to revise the spreading gain factor of partial message transmission, after it, representes spreading gain factor G0 with 04 initial bit simultaneously, when realizing in system; The N value that only need send spreading gain gets final product, and then the highest spreading gain factor of 4 bit supports is 2 ¹⁶, stop bits is a parity check bit; When catching frame head is complete 0 the time, and then acquiescence keeps the spreading gain factor G0 of last time to carry out message transmission, does not have spreading gain factor item thereafter, and after capturing the information frame head, promptly changing over to G0 is the despreading mode of spreading factor.Adopt the message transmission of this structure, have following characteristic:

is different with common adaptive communication system; The adaptive control of this system does not need the intervention of protocol layer; Directly carry out the change of adaptive gain through physical layer, the adjustment of spreading gain shields for protocol layer fully.This mode has been avoided increase protocol layer complexity, has reduced information interaction, has improved system flexibility, is more suitable for asynchronous communication system.

adopts the spreading gain of high-gain to catch; Can increase and catch accuracy rate; Improved acquisition probability, but and the conducting frame head carry out the required spreading gain of system when catching and confirm.

is in the time need not carrying out the spreading gain adjustment; The transmission item of no spreading gain factor bit, its information transmitted bit are equal to the normal information transmission.This will save spreading gain factor transport overhead under the basicly stable situation of network configuration.After said frame head spread processing module has been confirmed the coding of frame head, promptly adopt fixing long code that the frame head that forms is carried out spread processing, adopt the fixing maximum spreading gain factor (G=G of receiving-transmitting sides acquiescence simultaneously _Max) carrying out the spread spectrum transmission, corresponding receiving node end also adopts the maximum spreading gain factor (G=G _Max) carry out catching of frame head.

Said message processing module is used for according to determined current spreading factor G _P2Transferred communication information is carried out chnnel coding, serial to parallel conversion and spread processing to form corresponding spread spectrum information; It is provided with a spread spectrum parameter control unit; Be used for according to determined current spreading factor control channel coding, serial to parallel conversion and be applied to relevant each parameter of pseudo noise code (PN sign indicating number) of spread spectrum mutually so that the bandwidth of the spread spectrum information that produces meets preset requirement; Because the spreading gain factor (G), data continue the cycle (T) and the lasting cycle (t) of spreading code has: G=T/t; Therefore, confirming current spreading factor when said spread spectrum mode decision-making module is G _P2, the time, said spread spectrum parameter control unit can obtain corresponding spreading gain through the transmission rate of control data D (T); T is remained unchanged; T changes spreading gain through change, and the final output bandwidth of system is remained unchanged, to reduce the variation on the system hardware.

Said merging module is used for the formed frame head of catching is made an addition to said spread spectrum information, thus to form information frame as shown in Figure 7, wherein, the start bit of information frame head catch frame head be complete 1 o'clock be 0, catch frame head be complete 0 o'clock be 1.

Said molding filtration module is used for the spread spectrum information molding filtration of catching frame head with being added with, and detailed process and principle are known by those skilled in the art, so be not described in detail in this.

Said radio-frequency module is used for launching after the information via rf modulations with the output of molding filtration module.

See also Fig. 8, said information receiver comprises: frequency-variable module, correlation module, spreading gain determination module, spreading gain correcting module, the information that reaches are resolved module.

It is baseband I that said frequency-variable module is used for the radiofrequency signal that transmits at the sensing net is received back frequency conversion formation intermediate-freuqncy signal, Q signal.

Said correlation module is used for said intermediate-freuqncy signal and the local pseudo noise code that is produced are carried out relevant back to obtain corresponding coherent signal; Adopted fixing high-gain spread spectrum code word owing to catch the frame head spreading part spreads; So correlation module is to baseband I, Q signal carries out the long code correlation capturing to be handled to catch frame head.

Said spreading gain determination module is used for that said coherent signal is carried out the corresponding information despreading and handles the back to obtain corresponding frame head; And the information of carrying according to said frame head confirms to send the spreading gain factor that node side adopted of said radiofrequency signal; Promptly when frame head be complete 0 the time; The spreading gain factor that node side adopted that said spreading gain determination module can confirm to send said radiofrequency signal is identical with last time; When frame head is complete 1 the time, said spreading gain determination module reads 4bit after the start bit, and it is the spreading gain factor that node side adopted of the said radiofrequency signal of transmission; For avoiding mistake, said spreading gain determination module also can carry out parity check further to confirm the spreading gain factor to stop bits.

Said spreading gain correcting module is used for said coherent signal is analyzed to estimate corresponding received signal power and noise; And the determined spreading gain factor of said spreading gain determination module is revised so that the revised spreading gain factor adapts to the current environment of said sensing net according to said received signal power and noise; And the revised spreading gain factor is sent to the RST of said spread spectrum mode decision-making module to be sent to as respective nodes end in the sensing net that said information receiver was received, it comprises received signal power evaluation unit and noise estimation unit.

1, the evaluation method of power is following to received signal for said received signal power evaluation unit:

Said correlation module carries out relevant treatment with baseband signal and local pseudo noise code L (t), gets I, the correlation R of Q two-way respectively _I(k, m), R _Q(k, m), the correlation peak criterion that then is used to catch is: $R(k,m)=\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)},$ Wherein, k=0,1,2 ..., according to the maximum of correlation peak correlated results is carried out normalization and gets:

$\stackrel{\‾}{R}(k,m)=\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)}/\max \left(\sqrt{{R_I}^2(k,m)+{R_Q}^2(k,m)}\right),$

If catch frame head length is K, then said received signal power evaluation unit estimate a plurality of catch correlation peak on average as received signal power P _s, promptly have: $P_s=\frac{\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\mathrm{Max}\[R(k,m)}{K}.$

2, the evaluation method of said noise estimation unit is following;

A, signal are estimated

Local relevant code word with self carry out relevant treatment after must R _Ref(k m), can know after carrying out quadratic sum handles and can get $\sqrt{2}\left|R_{\mathrm{Ref}}(k,m)\right|,$ Equally this signal being carried out normalization gets: ${\stackrel{\‾}{R}}_{\mathrm{Ref}}(k,m)=R_{\mathrm{Ref}}(k,m)/\mathrm{Max}\left(R_{\mathrm{Ref}}(k,m)\right)$

Calculation is asked at b, the end of making an uproar

Deduct the value of estimating with receiving the correlation of signal, be used to ask the calculation end of making an uproar to get with local code:

$R_{\mathrm{noise}}(k,m)=\stackrel{\‾}{R}(k,m)-{\stackrel{\‾}{R}}_{\mathrm{ref}}(k,m)$

But in fact; Because the influence of channel circumstance or the influence that receiver itself causes; Ask calculate correlation peak and the correlation peak estimated and incomplete same; For further reducing signal the influence cause is estimated at the end of making an uproar, this remove except that correlation peak and near correlation peak average out to noise P behind the signaling point _n, promptly $P_n=\frac{\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{\underset{m\∉N}{m=1}}{\overset{T}{\mathrm{\Σ}}}{R}_{\mathrm{Noise}}(k,m)}{K(T-2D-1)},$ Wherein, N=[n-n _p-D, n-n _p+ D], about the correlation peak that D removes for needs is counted, be 2～3 times sampling multiple generally speaking.When spreading factor is G, the adding up when counting an of associated period to T, relation below existing: D=Nceil (T/G), wherein, ceil representes to round up.

3, signal to noise ratio is asked calculation

Said spreading gain correcting module can ask the calculation signal to noise ratio to be according to the estimation of said received signal power evaluation unit and noise estimation unit: SIR=P _s/ P _n, if the target signal to noise ratio is: SIR _Spec=P _s'/P _n, then: $\frac{\mathrm{SIR}}{{\mathrm{SIR}}_{\mathrm{Spec}}}=\frac{G_c}{G_{\mathrm{Spec}}},$ Wherein, G _cBe the determined spreading gain factor of said spreading gain determination module, G _SpecBe the revised spreading gain factor.

Said information is resolved module and is used for comprising that according to the said intermediate-freuqncy signal of the determined spreading gain factor pair of said spreading gain determination module separating the each item that extends to channel-decoding handles to obtain the entrained communication information of said quite signal; It is provided with a despreading control unit; Be used for according to the gain of the determined spreading gain FACTOR CONTROL of said spreading gain determination module information despreading and the original position of definite said communication information; In this execution mode; Said despreading control unit is according to the gain of the determined spreading gain FACTOR CONTROL of said spreading gain determination module Gain Adjustable tracker; Demodulates information is carried out in the gain of following the tracks of according to the Gain Adjustable tracker then to received signal, and the information after the demodulation is carried out the frame head search, and carries out can obtaining corresponding communication information after the processing such as channel-decoding.

Below will be described further the effect with sensing network node terminal of environmental suitability automatic gain adjustment of the present invention through emulation.

1) system's realizability and effect analysis

Simulated conditions: the spreading gain factor is 512, sampling multiple 2, data length 10, signal to noise ratio (snr) SNR=-20dB.

See also Fig. 9, its when the SNR=-20dB signal correlation values with estimate correlation and relatively illustrate picture group, wherein; A figure in the picture group of Fig. 9 is a signal correlation values and estimate the correlation comparison diagram, and the b figure in the picture group of Fig. 9 is the base map of making an uproar that directly removes behind the signal correction peak value, and the c figure in the picture group of Fig. 9 is that correlation deducts the signal graph of estimating behind the correlation; D figure in the picture group of Fig. 9 directly removes to estimate relevant peaks and the end signal graph of making an uproar that does not match behind the peak value, can be known by b figure, and it has comprised and relevantly itself brings the end of making an uproar in a large number; And it is visible according to c figure; Because channel and receive signal that traffic filter etc. brings and factor such as widen causes signal correction peak value wherein not removed fully, but adopts method of the present invention the end signal of making an uproar wherein to be subtracted much; Visible by d figure again; Removed the signal correction peak value and do not matched behind the peak value, and comprised the correlation end of making an uproar and compare, this end of making an uproar, is little nearly 20 times.

See also Figure 10 again, it is the simulation result picture group under the SNR=-40dB situation, wherein; A figure in the picture group of Figure 10 is signal correlation values and estimates the correlation comparison diagram; B in the picture group of Figure 10 figure is the base map of making an uproar that directly removes behind the signal correction peak value, and the c figure in the picture group of Figure 10 is that correlation deducts the signal graph of estimating behind the correlation, and the d figure in the picture group of Figure 10 directly removes the end signal graph of estimating behind relevant peaks and the peak value that do not match of making an uproar; Visible from figure; This moment, it was not obvious to remove the effect difference of estimating correlation and not removing after truly being made an uproar in the end in stack, and the two all can react the noise truth basically.

See also Figure 11, it is for estimating the picture group that concerns of SIR and noise under the correlation processing mode in removal, and its simulated conditions that adopts is: spreading gain 512, the multiple 2 of sampling, data length 10, SNR be-and 10dB～-50dB, wherein, lumda representes factor lambda.Visible by figure, along with the increase of signal to noise ratio, the end of making an uproar, reduce gradually, and SIR increases gradually, and optional spreading gain is more and more littler.

See also Figure 12, its for do not remove estimate SIR and noise under the correlation processing mode concern picture group, obviously its variation tendency and shown in Figure 11 similar.But under the signal to noise ratio condition with higher, observe, shown in figure 13, can find that the result that adopts removal to estimate after being correlated with can better be reacted the effect that low spreading gain brings, carrying out having higher reference value when system's short code is selected.

For observing the relation of correlation peak and frequency; See also Figure 14 to 16; Wherein, Figure 14 is the SIR signal picture group during from 0Hz～2000Hz for frequency shift (FS), and Figure 15 has the contrast picture group of frequency deviation and no frequency deviation during for SNR=-40dB; Figure 16 has the contrast picture group of frequency deviation and no frequency deviation during for SNR=-20dB; The three in simulated conditions is: spreading gain 512, sampling multiple 2, data length 10, SNR=-20dB obtain simulation result, and visible from each figure, there is not influence in frequency shift (FS) basically to the SIR of system.

2) systematic function and energy consumption analysis

The environmental suitability gain adjustment scheme that the present invention adopts does not need the scheduling of protocol layer, and its main energy consumption expense concentrates on the frame head of physical layer, divides three kinds of situation to analyze at present:

Situation 1: no signal is sent.

The chip of 2Mbps (chip) speed, 1023 spread spectrums;

The chip speed of 300kbps, 15 spread spectrums;

Calculate to capture a symbol (symbol), when clock accuracy was 5ppm, the systematic error of permission was at least 10us, and a symbol who is fit to 802.15.4 inserts the stand-by period.

The access stand-by period of adaptive gain adjustment scheme is extended for about ten times of 802.15.4, and total duration is about 0.5ms.

Can reduce through the mode that part is caught and insert the stand-by period, but after tentatively capturing suspect signal, carry out catching of next step again, increase the probability that leakage is caught but reduce turn-on time.

Situation 2: the signal emission is arranged, and spreading gain does not need change;

Be merely and catch frame head length.Can be set at 3bit.Total duration is about 1.5ms.

Under above-mentioned situation, the transmissible symbol number of 802.15.4 (868MHz place) is 30bit.Wherein, catch frame head when being 3bit, transmissible valid data are 27bit.

Situation 3: the signal emission is arranged, and spreading gain needs change;

For catching frame head length+spreading gain change factor.Be 8bit, total duration is 4ms.

Under above-mentioned situation, the transmissible symbol number of 802.15.4 (868MHz place) is 80bit.Wherein, catch frame head when being 3bit, transmissible valid data are 77bit.

Can find out that from Figure 17 and Figure 18 it is low more as far as the good more signal efficient of transmission conditions to catch the shared length of frame head, otherwise efficient is high more.After a stable condition, adopt the communication of 802.15.4 can't communicate in bad channel conditions.

The laser propagation effect that Figure 19 has provided this programme and 802.15.4 under the different channels environment relatively; For the transmission time, when transmission conditions were more excellent, the environmental suitability communication mode can be selected optimal communication modes automatically; Comparatively speaking; If this moment, system adopted the proper communication mode, when the transmission message length is the 100bit left and right sides, adopt the transmission time of environmental suitability communication mode will be shorter than the proper communication mode.And simultaneously, when channel circumstance was abominable, the big communication mode of spreading gain will be selected by system, and this moment, consumed time was longer, but can keep internodal communication.

If the node of simulation analysis random scatter is the situation of normal distribution with the 1km center, is example with the free space.

Los=32.44+201g d (Km)+201g f (MHz), wherein, Los is propagation loss, and unit is dB, and d is a distance, and unit is Km, and f is an operating frequency, and unit is MHz.In 802.15.4, transmitting power-3dBm, received power-92dBm, the greatest path loss of tolerance is 95dBm.And adopt largest tolerable path loss of the present invention this moment is 105dBm.

Can know that by Figure 20 analysis the path loss of scattering node will have probability about 30% greater than 95dBm, and almost not have the probability greater than 105dBm.Can know that under above-mentioned simulated conditions, but sensing network passband of the present invention will be big by 30% than 802.15.4.

In sum, the sensing network node terminal with the adjustment of environmental suitability automatic gain of the present invention has the following advantages:

strengthened the adaptability to environment, when guaranteeing communication efficiency, guaranteed good communication speed.The main target of adaptive communications is to guarantee the compatibility of network node to information flow-rate and transmission range, and realizes the automatic adjustment of communication mode based on the minimum thought of total system energy.

The traffic rate and the sensitivity of

each node are all variable; And this gain adjustment does not need the intervention of protocol layer; Only come to realize automatically the adjustment of different communication speed, reduce the information interaction burden of network layer greatly through the frame head of physical layer.

especially is fit to information interaction less asynchronous communication system of shaking hands.

Claims (8)

1. the sensing network node terminal with the adjustment of environmental suitability automatic gain is characterized in that comprising information receiver and information transmitting apparatus, and wherein, said information transmitting apparatus comprises:

The spread spectrum mode decision-making module, the definite current spreading factor that need adopt of the RST that a first node end is sent in the sensing net that is used for receiving according to said information receiver, said information transmitting apparatus present located role and state to the signal of communication of said first node end emission;

Frame head spread processing module; Be used for based on determined current spreading factor and last time confirming the coding of current frame head, and the spreading gain that employing and said first node end are made an appointment carries out spread spectrum to form the respective capture frame head to determined frame head to the transmit spreading factor that adopted of said first node end;

Message processing module; Be used for the transferred communication information being carried out chnnel coding, serial to parallel conversion and spread processing to form corresponding spread spectrum information according to determined current spreading factor; It is provided with a spread spectrum parameter control unit, is used for according to determined current spreading factor control channel coding, serial to parallel conversion and is applied to relevant each parameter of pseudo noise code of spread spectrum mutually so that the bandwidth of the spread spectrum information that produces meets preset requirement;

Merge module, be used for the formed frame head of catching is made an addition to said spread spectrum information;

The molding filtration module is used for the spread spectrum information molding filtration of catching frame head with being added with;

Radio-frequency module is used for launching after the information via rf modulations with the output of molding filtration module;

Said information receiver comprises:

Frequency-variable module is used for that the radiofrequency signal that transmits at the sensing net is received the back frequency conversion and forms intermediate-freuqncy signal;

Correlation module is used for said intermediate-freuqncy signal and the local pseudo noise code that is produced are carried out relevant back to obtain corresponding coherent signal;

The spreading gain determination module is used for that said coherent signal is carried out the corresponding information despreading and handles the back obtaining corresponding frame head, and confirms to send the spreading gain factor that node side adopted of said radiofrequency signal according to the information that said frame head carries;

The spreading gain correcting module; Be used for said coherent signal is analyzed to estimate corresponding received signal power and noise; And the determined spreading gain factor of said spreading gain determination module is revised so that the revised spreading gain factor adapts to the current environment of said sensing net, and the revised spreading gain factor is sent to the RST of said spread spectrum mode decision-making module to be sent to as respective nodes end in the sensing net that said information receiver was received according to said received signal power and noise;

Information is resolved module; Be used for comprising that according to the said intermediate-freuqncy signal of the determined spreading gain factor pair of said spreading gain determination module separating the each item that extends to channel-decoding handles to obtain the entrained communication information of said intermediate-freuqncy signal; It is provided with a despreading control unit, is used for according to the gain of the determined spreading gain FACTOR CONTROL of said spreading gain determination module information despreading and the original position of definite said communication information.

2. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 1, it is characterized in that: said spread spectrum mode decision-making module is according to G _P2+ G _S2>=G ₀+ G _S1+ Δ S _InNeed to confirm the current spreading factor of employing, wherein, G _P2Be the current spreading factor that need adopt, G _S2Be the transmitting power that adopts, G ₀For the revised said first node end that is sent to by said spreading gain correcting module transmits the spreading factor that signal adopts, G _S1Be the transmitting power that said first node end adopts, Δ S _InMaximum difference for corresponding each the node side device sensitivity of sensing net.

3. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 2, it is characterized in that: said spread spectrum mode decision-making module also is provided with map unit, is used for as determined current spreading factor G _P2To its mapping that makes progress, promptly work as determined current spreading factor G when not existing _P2Be in [2 ^N-1-1,2 ^N-1] in the time of between, makes the current spreading factor G after the mapping _P2Be 2 ^N-1, wherein N is a positive integer.

4. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 1 is characterized in that: said frame head spread processing module adopts fixing long code to carry out spread processing.

5. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 1, it is characterized in that: said spreading gain of making an appointment is maximum spreading gain.

6. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 1; It is characterized in that: transmitted the spreading factor that adopted not simultaneously when determined current spreading factor and last time to said first node end, the determined present frame header encoder of said frame head spread processing module is complete 1 the combination of catching position and said current spreading factor; Transmitted the spreading factor that adopted when identical when determined current spreading factor and last time to said first node end, and the determined present frame header encoder of said frame head spread processing module is merely complete 0 the position of catching.

7. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 1 is characterized in that said spreading gain correcting module comprises:

The received signal power evaluation unit is used for basis

Estimating received signal power, wherein, P _sBe received signal power,

R _I(k, m) and R _Q(k m) is coherent signal;

The noise estimation unit is used for basis

Estimated noise, wherein, P _nBe noise,

And

R _Ref(k m) is local relevant code word and the result who self carries out after relevant, N=[n-n _p-D, n-n _p+ D], and D counts for the correlation peak that needs to remove, wherein, K is for catching frame head length, and T is that adding up of associated period counted, and n is for correlation peak time corresponding point occurring, n _pBe the time that previous accumulation period finishes, N needs the correlation peak of removal and the correlation peak behind near the signaling point thereof, and m is a time corresponding point in the one-period.

8. the sensing network node terminal with the adjustment of environmental suitability automatic gain as claimed in claim 7 is characterized in that the revised spreading gain factor of said spreading gain correcting module is:

Wherein, G _cBe the determined spreading gain factor of said spreading gain determination module, G _SpecBe the revised spreading gain factor, SIR=P _s/ P _n, SIR _SpecBe the target signal to noise ratio.

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