A method for adaptive switching of a UV and RF hybrid communication link

Abstract

The application discloses a kind of ultraviolet light and radio frequency mixed communication link adaptive switching method, specifically includes the following steps: step 1, route auxiliary calculation sending end and the position information of receiving end, judge whether UV / RF data transmission uses cooperation mode;Step 2, when cooperation mode cannot be used in special circumstances, other ultraviolet terminal equipment in non direct view range is passed through single-hop or multi-hop mode;Step 3, when cooperation mode is used, the communication distance L UV It is determined according to the position information obtained;Step 4, when selecting ultraviolet link as data transmission link, the emission power of ultraviolet transmitting terminal array antenna is adaptively adjusted;Step 5, when ultraviolet link reaches the index requirement of communication link, distribute encrypted information;The communication distance L UV Between communication equipment is obtained.Ultraviolet link adaptive emission power adjustment and distribution key are combined with radio frequency link to increase effective communication distance, improve the resource utilization rate of link and the security of communication.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultraviolet light communication and relates to a method for adaptively switching an ultraviolet light and radio frequency mixed communication link. BACKGROUND

[0002] Ultraviolet light communication is a wireless communication technology means for data transmission by means of direct and scattering of atmospheric radiation in the day-blind ultraviolet (UV) band, which has the advantages of good local privacy, strong anti-interference ability, low eavesdropping rate, etc. The radiation power of the UV communication system can be reduced to a minimum according to the communication distance requirement, and therefore it is particularly suitable for secret communication in a local area under complex terrain environment. The scattering of ultraviolet light in the atmosphere changes the direction of energy transmission of ultraviolet light, which lays the foundation for ultraviolet light scattering communication. However, the attenuation of the absorption band limits the reliable communication distance of ultraviolet light.

[0003] Traditional radio frequency (RF) communication is a wireless transceiver system that carries information by means of radio frequency electromagnetic waves, which has the advantage of high reliability. However, since the RF communication needs to assume an antenna in advance, it cannot meet the requirements of mobile and rapid response battlefield communication, and the communication mode is not flexible. Moreover, wireless and microwave communication is easy to be eavesdropped, interfered and destroyed, and is not suitable for electromagnetic silence communication. The combination of ultraviolet light communication and traditional radio frequency communication can complement each other's advantages and make up for the respective shortcomings of ultraviolet and radio frequency links under some conditions. The UV / RF mixed link networking technology has a broad application prospect.

[0004] The current wireless and wired communication methods meet the needs of military and civilian communication to a large extent, but in complex terrain, strong electromagnetic interference environment, radio silence and other military situations, optical fiber and cable communication methods cannot be laid in advance in complex terrain, and the communication line is easily damaged, which is not suitable for real-time, variable and dynamic military battlefield communication environment. In order to better meet the needs of the above communication in future information warfare, UV / RF mixed link is used for information transmission, which usually takes ultraviolet link as the main link and radio frequency link as the auxiliary link, and switches according to the transmission distance and the link quality of the ultraviolet link. Radio waves and radio frequency communication are easy to be eavesdropped and interfered, and are not suitable for secret communication in "electromagnetic silence" situation. SUMMARY

[0005] The application aims to provide a method for adaptive switching of ultraviolet light and radio frequency mixed communication link, which has the characteristics of good local system security, strong anti-interference ability and all-weather and all-direction working. The traditional ultraviolet light communication and radio frequency communication show obvious shortcomings under some conditions, so the ultraviolet light communication and the traditional radio frequency communication are combined to complement each other, the mixed system is switched to the UV relay transmission link in a hard switching mode, the signal transmission is realized by the ultraviolet light communication through the relay transmission, and the mixed link networking technology has wide application prospect.

[0006] The technical scheme used in the application is a method for adaptive switching of ultraviolet light and radio frequency mixed communication link, which specifically comprises the following steps:

[0007] Step 1, the position information of the sending end and the receiving end is calculated by route assistance, so as to obtain the communication distance L between the sending terminal and the receiving terminal UV , whether the UV (Ultraviolet, UV) / RF (Radio Frequency, RF) data transmission adopts a cooperative mode is judged;

[0008] Step 2, when the cooperative mode cannot be adopted under special circumstances, each ultraviolet terminal device is used as a relay node, and the reliable chain building requirement of relay forwarding is provided for other ultraviolet terminal devices in a non-direct view range through single-hop or multi-hop mode, so as to prolong the effective communication distance of the ultraviolet terminal device ad hoc network;

[0009] Step 3, when the cooperative mode is adopted, the communication distance L UV is determined according to the obtained position information, L UV is the communication distance obtained by route assistance, whether the transmission distance of the ultraviolet link is greater than is judged, if L UV is greater than , the radio frequency link is switched to for information transmission, if L UV is less than or equal to , the ultraviolet link is switched to for information transmission, and the control decision of the switching switch is made according to the result;

[0010] Step 4, when the ultraviolet link is selected as the data transmission link, an integrated ultraviolet light source array antenna is used, the transmission power of the ultraviolet link sending array antenna is adaptively adjusted according to the communication distance L UV and the link signal-to-noise ratio fed back by the ultraviolet receiving terminal, until the error rate of the receiving terminal under the selected scheme parameters reaches the index requirement;

[0011] Step 5, when the ultraviolet link reaches the communication link index requirements, distribute the key information, to prevent the ultraviolet link from being eavesdropped when the radio frequency link is used to transmit information if the ultraviolet link still fails to meet the error rate index requirements at the maximum transmitting power of the array antenna, the hybrid system switches to the radio frequency link for transmission.

[0012] Compared with the prior art, the application has the beneficial effects that the ultraviolet link adaptive adjustment of transmitting power and the distribution of keys in combination with the radio frequency link increase the effective communication distance, improve the resource utilization rate of the link and the security of communication. BRIEF DESCRIPTION OF DRAWINGS

[0013] Fig. 1 is the ultraviolet light and radio frequency hybrid link adaptive switching flowchart of the application;

[0014] Fig. 2 is the ultraviolet light transmitting end adaptive adjustment flowchart of the application. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0016] As Figs. 1-2 , each communication transceiver device is loaded with GPS or Beidou and other position acquisition equipment, and the position information of the current communication device can be known, and the communication distance L between the communication devices is obtained UV .

[0017] According to step 1, the position information of the transmitting end and the receiving end is calculated according to the routing assistance, so that the communication distance L between the transceiver terminals is obtained UV , the artificial judgment UV / RF data transmission whether to use the cooperative mode;

[0018] Step 2, in special cases, when the cooperative mode cannot be selected for information transmission, each UV terminal device acts as a relay node, and provides reliable relay forwarding link building requirements for other UV terminal devices in the non-direct view range through single-hop or multi-hop mode, and prolongs the effective communication distance of the UV terminal ad hoc network;

[0019] Step 3, according to the routing assistance calculation, the communication distance L between the transmitting end and the receiving end is obtained UV , and compared with the of the ultraviolet link. If L UV is greater than the If L UV is less than or equal to the maximum communication distance of the UV link, the UV link is selected as the information transmission link. The UV link is used for signal transmission.

[0020] When the UV communication link is selected as the information transmission link, the maximum communication distance d between the transceiving devices and the link signal-to-noise ratio fed back by the UV receiving terminal are estimated, and the transmission power of the UV transmitting array antenna is adaptively adjusted until the bit error rate of the receiving terminal under the selected scheme parameters reaches the index requirement. UV

[0021] When the UV link reaches the index requirement of the communication link, the key information is distributed to prevent eavesdropping when the UV link fails to reach the index requirement and the radio frequency link is used for information transmission. If the UV link still fails to reach the bit error rate index requirement at the maximum transmission power of the array antenna, the hybrid system switches to the radio frequency link for transmission.

[0022] The UV link is adaptively adjusted for transmission power and distribution of key information, and the radio frequency link is combined to extend the effective communication distance L UV The actual communication distance between the transceiving terminals is estimated according to the lambertw function as follows:

[0023]

[0024] In formula (1), d is the actual communication distance between the transceiving terminals; the actual communication distance d changes with the transmission power, the atmospheric extinction coefficient, the acceptance aperture area of the photomultiplier tube, and the geometric parameters of the transmitting terminal; P t is the transmission power of the ultraviolet light, K s is the atmospheric scattering coefficient, A r is the acceptance aperture area, P s is the scattering phase function, k e is the atmospheric channel attenuation coefficient; Φ t is the transmitting terminal divergence angle, θ t is the transmitting terminal elevation angle, Φ r is the receiving terminal field of view angle, and θ r is the receiving terminal elevation angle.

[0025] For "solar blind" ultraviolet light short-distance communication, there are usually line of sight (LOS) and non-line of sight (NLOS) two ways.

[0026] In the line of sight (LOS) link, the received optical power P d,LOS of the receiving terminal ultraviolet detector is as follows:

[0027] ​

[0028] When the ultraviolet light is transmitted in a short distance, A in formula (13) is the aperture area of the ultraviolet detector, k r is the atmospheric channel attenuation coefficient; the actual communication distance d and the atmospheric attenuation factor are two important factors affecting the received power, so the line-of-sight communication is greatly affected in the complex and changeable climate environment; e

[0029] The corresponding path loss L formula is:

[0030]

[0031] In the transmission process, the optical power is mainly affected by the path loss and the atmospheric attenuation; taking the on-off keying (OOK) modulation system as an example, assuming that the bandwidth of the detector is twice the data transmission rate, η r is the efficiency of the detector, G is the gain multiple of the detector, P d,LOS is the received optical power of the LOS link, R is the data transmission rate, h is the Planck constant, c is the speed of light, and λ is the wavelength of light; the signal-to-noise ratio SNR d,LOS of the receiving end is:

[0032]

[0033] The bit error rate BER d,LOS after the on-off keying (OOK) modulation is:

[0034]

[0035] wherein Q(x) is the Q function, and erfc(x) is the complementary error function;

[0036] In the non-line-of-sight communication link, the received optical power P d,NLOS of the ultraviolet detector at the receiving end is:

[0037]

[0038] wherein k e is the atmospheric channel attenuation coefficient, which is composed of the atmospheric scattering coefficient k s and the atmospheric absorption coefficient k a ; k e =k s +k a ; it can be seen from the formula that the received optical power P d,NLOS of the ultraviolet detector is affected by the wireless atmospheric channel attenuation coefficient k e ;

[0039] In the information transmission process, the received optical power P d,NLOS ​Affected by path loss and atmospheric attenuation, Φ t is the transmitting end divergence angle, Φ r is the receiving end field of view angle; path loss L NLOS under non-line-of-sight ultraviolet light communication is:

[0040]

[0041] The signal-to-noise ratio formula SNR under on-off keying (OOK) modulation system is: d,NLOS

[0042]

[0043] Wherein, the bit error rate of the wireless ultraviolet light communication system is the number of error bits in a unit of time divided by the total number of transmitted bits, which is calculated by detecting the receiving end; the corresponding bit error rate BER is:

[0044]

[0045] Wherein, λ s is the average number of signal photons reaching the receiving end in each pulse interval, λ i is the average number of interference photons reaching the receiving end in each pulse interval, m T is the optimal threshold value; k! is the factorial of k, k is a parameter in the formula, in order to ensure the communication quality, BER must be less than 10 -5 , if BER can reach 10 -3 , the communication can also be realized, but the noise is larger; the expressions of λ i , λ s and m T are respectively:

[0046]

[0047]

[0048]

[0049] Wherein, η1 is the PMT detector efficiency, η2 is the filtering efficiency of the filter; L T is the path loss in the transmission process; R bT is the bit rate of the transmitting end; the energy of each photon is hυ, wherein h is the Planck constant, υ is the frequency of the transmitting photons of the transmitting end, υ=c / λ, λ is the wavelength, and c is the speed of light; K is the number of interference photons, P ij is the transmitting power of the jth interference, L Ij is the path loss of the jth interference end reaching the receiving end, R bIj ​is the bit rate of the jth interfering terminal, where j takes 1 in the model with only one interfering link; m T The optimal threshold is calculated to obtain the bit error rate, because the bit error rate is one of the most important indexes to evaluate the quality of communication.

[0050] While embodiments of the present application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and spirit of the present application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. A method for adaptive switching of a UV and RF hybrid communication link, the method comprising: Specifically comprising the following steps: Step 1, the routing auxiliary calculation sends the location information of the terminal and the receiving terminal, so as to obtain the communication distance L between the transmitting terminal and the receiving terminal UV , judging whether the ultraviolet or radio frequency data transmission adopts the cooperative mode; Step 2, when the cooperative mode cannot be adopted in special cases, each ultraviolet terminal device acts as a relay node, provides reliable relay forwarding link establishment requirements for other ultraviolet terminal devices out of the direct range through single-hop or multi-hop mode, and prolongs the effective communication distance of the ultraviolet terminal device ad hoc network; Step 3, when using the cooperative mode, determining the communication distance L according to the acquired position information UV , L UV is the communication distance obtained with the help of routing, judging whether the transmission distance of the ultraviolet link is greater than L UV is greater than switching to the radio frequency link to transmit information, if L UV is less than or equal to switching to the ultraviolet link to transmit information, and controlling the switching switch according to the result Step 4, when the ultraviolet link is selected as the data transmission link, an integrated ultraviolet light source array antenna is used, and the transmitting power of the transmitting array antenna of the ultraviolet link is adaptively adjusted according to the communication distance L UV and the link signal-to-noise ratio fed back by the ultraviolet receiving terminal until the bit error rate of the receiving terminal under the selected scheme parameters reaches the index requirement. Step 5, when the ultraviolet link reaches the index requirements of the communication link, distribute the key information to prevent the ultraviolet link from being eavesdropped when the radio frequency link is used for transmitting information if the ultraviolet link still cannot reach the error rate index requirements at the maximum transmitting power of the array antenna, then the hybrid system switches to the radio frequency link for transmission.

2. The method of claim 1, wherein, Adaptive adjustment of the UV link for transmission power and distribution of key information, combined with the RF link to extend the effective communication distance L UV ; The actual communication distance between the transceiving terminals is estimated according to the lambertw function as follows: In formula (1), d is the actual communication distance between the two ends of the transceiver; the actual communication distance d varies with the transmission power, the atmospheric extinction coefficient, the acceptance aperture area of the photomultiplier, and the geometric parameters of the transmitting end; P t is the emission power of ultraviolet light, K s is the atmospheric scattering coefficient, A r is the acceptance aperture area, P s is the scattering phase function, k e is the atmospheric channel attenuation coefficient; Φ t is the transmitting end divergence angle, θ t is the transmitting end elevation angle, Φ r is the receiving end field of view angle, θ r is the receiving end elevation angle; In a line-of-sight (LOS) link, the UV detector at the receiving end receives the optical power P d,LOS is: When the ultraviolet light is transmitted in a short distance, k e is the atmospheric channel attenuation coefficient, and d is the actual communication distance from the transmitting end to the receiving end. The actual communication distance d and the atmospheric attenuation factor are two important factors affecting the received power. Therefore, in a complex and changeable climate environment, the line-of-sight communication is greatly affected. The corresponding path loss L formula is as follows: Wherein, in the transmission process, the optical power is mainly affected by path loss and atmospheric attenuation; taking on-off keying (OOK) modulation system as an example, assuming that the bandwidth of the detector is twice the data transmission rate, η r is the efficiency of the detector, G is the gain multiple of the detector, R is the data transmission rate, h is the Planck constant, c is the speed of light, and λ is the wavelength of light; the signal-to-noise ratio (SNR) d,LOS at the receiving end is: bit error rate (BER) after on-off keying (OOK) modulation d,LOS is: Wherein, Q(x) is the Q function; erfc(x) is the complementary error function; In a non-line-of-sight communication link, the ultraviolet detector at the receiving end receives optical power P d,NLOS is: wherein k e is the atmospheric channel attenuation coefficient, which is composed of the atmospheric scattering coefficient k s and the atmospheric absorption coefficient k a ; that is, k e = k s + k a ; as can be seen from the formula, the received light power P d,NLOS of the ultraviolet detector is affected by the wireless atmospheric channel attenuation coefficient k e ; In the process of information transmission, the ultraviolet detector receives light power P d,NLOS Affected by path loss and atmospheric attenuation, Φ t is the emission angle of the transmitting end, Φ r is the receiving end field of view angle; under the non-line-of-sight ultraviolet light communication, the path loss L NLOS is expressed as: The signal-to-noise ratio formula SNR under OOK modulation system d,NLOS is: Wherein, the error rate of the wireless ultraviolet light communication system is the number of error bits in a unit time divided by the total number of bits transmitted, which is calculated by detecting the receiving end; and the corresponding error rate BER is as follows: where λ s is the average number of signal photons arriving at the receiving end per pulse interval, λ i is the average number of interference photons arriving at the receiving end per pulse interval, m T is the optimal threshold value; k! is the factorial of k, k is a parameter in the formula, in order to ensure the quality of communication, the BER must be less than 10 -5 , if the BER can reach 10 -3 , the communication can also be achieved, but the noise is larger; λ i , λ s and m T are expressed as follows: Wherein, η1 is the PMT detector efficiency, η2 is the filter efficiency; L T is the path loss of the transmission process; R bT is the bit rate of the transmitting end; the energy of each photon is hυ, wherein h is the Planck constant, υ is the frequency of the photons emitted by the transmitting end, υ=c / λ, λ is the wavelength, and c is the speed of light; K is the number of photons of the interfering end, P ij is the transmission power of the jth interfering end, L Ij is the path loss of the jth interfering end to the receiving end, R bIj is the bit rate of the jth interfering end, and j is 1 in the model in which only one interfering link exists; m T The optimal threshold is calculated to obtain the bit error rate, because the bit error rate is one of the most important indicators for evaluating the quality of communication.

Images