• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Summary: The present invention relates to a digital radio terminal comprising an early warning device which detects if there is a risk of communication interruption based on a comparison of an estimated value of interference and noise signaling (SINR) signal and a predetermined first threshold yard or a a comparison between the time derivative of said estimated yard on SINR and a predetermined second threshold yard or an estimated value of the interference signal effect and an estimate of the type of interference, or a combination of these methods. The Early Yarning device creates a proactive Yarning to the user of the terminal. The present invention also includes a digital radio system comprising such terminals.
    公开号:SE1100556A1
    申请号:SE1100556
    申请日:2011-07-21
    公开日:2013-01-22
    发明作者:Kia Wiklundh；Peter Stenumgaard；Erik G Larsson
    申请人:Totalfoersvarets Forskningsins；
    IPC主号:
    专利说明:

    Summary: The present invention relates to a digital radio terminal comprising an early warning device which detects if there is a risk of communication interruption based on a comparison of an estimated value of interference and noise signaling (SINR) signal and a predetermined first threshold yard or a a comparison between the time derivative of said estimated yard on SINR and a predetermined second threshold yard or an estimated value of the interference signal effect and an estimate of the type of interference, or a combination of these methods. The Early Yarning device creates a proactive Yarning to the user of the terminal. The present invention also includes a digital radio system comprising such terminals. The present invention relates to a digital radio terminal comprising an early yarning unit and a digital radio system comprising such terminals.
    Experience shows that unforeseen communication problems during emergency operations can have serious consequences for both personal safety and the ability to carry out a successful operation. Recently, in modern radio systems for alarm operations and security operations, there has been a transition to digital radio systems as opposed to analogue radio systems. Analog radio systems normally have a gradual tightening of the communication channel and the user thus becomes aware that communication problems are likely to arise. This is not the case in digital radio systems.
    Emergency personnel, such as polls, firefighters and other rescue personnel, depend on reliable wireless communication for emergency operations. Several real examples show how an operation can be disturbed in a very recognizable way and hot uncontrollable if the wireless voice communication is interrupted for any reason. A typical example is if the smoke diver's radio for a firefighter breaks down. Another example is when intentional staring is used against emergency personnel. During the EU summit in Gothenburg in 2001, the situation became uncontrollable when the demonstrators took advantage of the police radio system's vulnerability to electromagnetic interference. They managed to expand the radio system during the critical phases of the operation. Intentional harassment is now often used by criminals and large equipment against radio systems can be easily purchased on the INTERNET for only a few hundred dollars.
    In older analogue systems, it was possible to detect that communication problems approached before the communication channel was seriously disturbed, since analog devices generally have a smooth transition from a "functioning" to a "non-functioning" state, was common according to the figure. If the device is used for voice communication, the indication can typically appear as an increased noise level. This built-in yarning allows the user to take action to prevent interruptions. 2 In a digital radio system, the transition from a good to a bad state takes place without any change. A service that gives the user early yarning when the digital system approaches Transition would be a significant help in identifying unpredictable communication problems before they lead to interruptions. If this service is integrated into the command and control system for the operation, significant decision support can also be provided to identify enemy interference or other local interference problems at terminals and appropriate receiving guards can be taken.
    In some cases, there are solutions today to indicate when the real signal to interference and noise ratio (SINR), defined as the signal power divided by the sum of the power level of noise and interference in the receiver unit, is close to transitioning to a non-functioning state. . Noise is defined as thermal noise originating in electronic circuits in the radio receiver and from atmospheric sources. Interference is defined as man-made signals, both from unintentional disturbances and from intentional disturbances. The total interference is thus the sum of the level of noise and interference in the receiver unit.
    An example of such an indication that Transition is imminent is the hand-over of mobile terminals to a new base station. A second example is indicators that warn when SINR falls below a certain level. However, they are all reactive in the sense that they do not warn in advance or how quickly an approaching communication problem is approaching. When an "indicator" warns, a handover has already taken place or the terminal already has problems.
    Handover is also not always an option in alarm operations, such as in underground facilities, tunnels, buildings and large ships. Communication solutions for such environments are either special systems without base stations or systems that use mobile base stations for Okad tacking, e.g. systems based on TETRA. The TETRA standard is used today in about 100 years and the most prominent application is for emergency personnel and emergency responders. In such scenarios, handover is not always an option and interruptions will occur if SINR falls below a critical value. SINR varies with the position of a particular terminal. In addition, the interference from adjacent cells varies with the position of the terminal. This means that even without hostile interference and unintentional interference noise, communication problems can arise. 3 The figure shows the communication quality of a digital channel as a function of SINR. is the value of SINR yid the transition point where a rapid transition takes place from a functioning to a non-functioning communication state and Ay is an example of how an area can be chosen within which an early yarning is to be activated. Such a service that provides early yarning will be proactive.
    At the terminal level, a service for early yarning should preferably detect, and give a yarning, not only when SINR goes below 7, + Ay in a certain terminal but also take into account how fast the threshold value y approaches. Alternatively, the detection of an imminent communication problem can be based on the type of noise and interference.
    At the system level, a service for early warning should take into account how nearby users experience the situation and if there are other signs that indicate impending communication problems. This may be a transfer of status messages from each terminal to the system level. At the system level, this service should preferably also be available as a decision support to warn, if a problem with noise, interference or active staring approaches and threatens the safety of staff. The overall purpose is to identify when a noise or interference problem is approaching so that either the user or the system itself can act to prevent interruptions.
    The present invention provides a solution to the problems discussed above by being challenged in the manner set forth in the appended independent claims. The present claims relate to advantageous embodiments of the invention.
    The invention will be described in more detail below with reference to the accompanying drawing, in which the figure shows the difference between an analogue and a digital radio system when it comes to how fast they change from a functioning to a non-functioning state as a function of SINR, yi, and transition point, y, and the range, Ay, within which an early yarning is to be given is defined.
    At the individual level, the invention relates to a digital radio terminal. At the system level, it also leads to a network at such terminals. Such a network may include a management and control unit that receives information from different terminals and makes decisions concerning some or all terminals in the network. A digital radio terminal according to the invention comprises a device for early earning which determines whether there is a risk of communication interruption based on a comparison of an estimated value of SINR and a predetermined first threshold, or a comparison between the time derivative of the said SINR and a predetermined second. threshold value, or an estimated value of the interference signal effect and an estimate of the type of interference, or a combination of these methods. When it is determined that there is a risk, the unit for premature yarning creates a proactive yarning to the other person at the terminal.
    An example of this is to determine that there is a risk of communication interruptions when the relationships {Y; (1i0)) 7c + Ay are fulfilled at the same time. y, is SINR father terminal) 2; (t7; (t)) __ 0 is the time derivative daray, i is the position of the terminal, t is the time, y, is the transition point when the transition from a functioning to a non-functioning communication state with respect to SINR occurs rapidly and Ay is a selected area within which an early yarning is to be created.
    The early warning at the terminal level can take the form of noise added to the audio signal. Said noise can be arranged to increase in strength when the starting point approaches in order to mimic the pre-assembly of the communication channel of an analogue radio channel. In this way, the other person experiences the change in a way he is used to. The early warning can instead take other appropriate forms, such as roaring crackling when the Oyergang point approaches.
    In order to be able to classify the noise and interference the terminal is subjected to, in one embodiment of the invention the terminal comprises a signal processing unit which decodes the received signal, remodulates it and subtracts the remodulated signal from the received signal, thereby creating a residual signal comprising second channel interference. base stations, intentional and unintentional noise signals and thermal receiver noise. SINR is estimated as the remodulated signal power divided by the signal power of the residual signal.
    When it comes to the classification of noise and interference, the terminal further comprises in an embodiment of the invention an analysis unit which, based on SINR, the thermal noise level according to the system specification, said residual signal and the position of the terminal estimates the signal power of the interference. The effect of the residual signal can be compared with what could be expected in the geographical position where the receiver is located, either by using a model for large-scale propagation, a database with thank-you maps or both. If the residual signal effect is greater than what is expected, the said residual signal is classified as intentional or unintentional major signals. If not, the noise and interference signal are classified as co-channel. If the power of the remodulated signal is lower than expected, the situation is classified as law SINR.
    The classification of the type of large signal that is available can be done with a classification algorithm such as kurtosis estimation in higher-order statistics. A kurtosis value near zero indicates a normally distributed signal. Based on this, the noise and interference analyzer classifies noise and the interference signal as either unintentional / intentional or co-channel interference.
    When an early yarning is created, in one embodiment of the invention, the terminal generates a status message informing the user of the probable cause of the problems, which includes information about the type of noise and interference and SINR.
    Standard terminals contain some of the information required in a terminal according to the invention. Other information is missing. The following table summarizes this.
    Parameter Availability Thermal noise Available in standard terminals Position Available in standard terminals 7c, The smallest SINR required for a functioning system. This value is often found in the technical specification of a system.
    Res Rest after correlation. Not always available in standard receivers. Must be appreciated in a signal processing unit.
    In order for users of terminals to be informed of the problems encountered by other terminals and to possibly adapt the use of a terminal, in an embodiment of the invention the status message is supplemented with a terminal position throughout the network to which the terminal is connected. The terminals are arranged to receive this information from said network. At a higher level, as in a digital radio system comprising a network of digital radio terminals as above, the system comprises a line and control unit configured to exchange information with the terminals. The command and control unit receives from the terminals the status messages together with the respective position and takes based on this receive guards, such as frequency change or change of the physical position for a single terminal, a group of terminals or all terminals in the network. In a network that has a central (base) station, it is easy to imagine that the line and control unit is integrated in this station. However, the line and control unit will function as long as it is connected to each terminal, regardless of whether there is one, many or no base station.
    In one embodiment of the invention, which may use multiple-input multiple-output (MIMO) type antenna systems, the classification of noise and interference may be made by studying the covariance of the residual signal from different antenna elements.
    Consider a sequence of vectors yk received by a group antenna with M elements yk = hsk + gsk '+ w, where h is the channel matrix of the transmitter, so-called are emitting symbols of interest, g is the channel of the magnifier, so-called represents computer symbols transmitted by the larger and w is a vector of thermal noise. The task is to determine am g = 0 (there is intentional / unintentional interference) or am g = 0 (there is no intentional / unintentional interference). If so-called can be detected reliably, a residual signal can be obtained which consists only of interference and thermal noise by subtracting the detected signal of interest using standard methods such as so-called interference rejection combining - even in strong interference such as the interference channel is significantly different An equivalent for the desired transmitter. If we assume ideal detection and subtraction of the interesting signal hsk, the residual signal can be written as zk = gsk` + w.
    One way to determine if there is intentional / unintentional interference # 0) or N not = 0) is to form the covariance matrix for sample R ,, where When k = 1 7 the number of available vectors, and create a statistical test based on the eigenvalues of R .
    A simple test is, for example, to look at the ratio between the largest eigenvalue 5 for Az and the mean of the N-1 smallest eigenvalues and compare this with a threshold value. This problem is similar to problems that arise in spectrum scanning for cognitive radio with multiple antennas and techniques from this field can be used more or less directly as those skilled in the art know. Anyone who wants to study this more closely can read: Y. Zeng and Y.-C. Liang, "Eigenvalue-based spectrum sensing algorithms for cognitive radio", IEEE Trans. on Communications, vol. 57, no. 6, pp. 1784-1793, June 2009, which is hereby incorporated by reference.
    If so-called can not be detected in a reliable way, it is not possible to form a residual signal. Then one must resort to completely blind methods which are known to the person skilled in the art and which can be used to determine the number of independent signals which yk includes.
    There is a rich literature on this. Anyone who wants to study this more closely can read: M. Wax, and T. Kailath, "Detection of signals by information theoretical criteria, IEEE Trans. On Acoustics, Speech, and Signal Processing, vol. 33, no. 2, pp. 387 -392, April 1985, which is hereby incorporated by reference. If the number of signal components is greater than one, it can be concluded that there is a major transmitter. An example of such a method is to form the covariance matrix 1 = N k = 1 then determine the number of signal components via the so-called MDL criterion nAll (pk) i = k + 1 1 ldi max 1 + -2k (2p — k) log N —1 where {A1, Ap} are the eigenvalues for R. 8
    权利要求:
    Claims (8)
    [1] 1. A digital radio terminal comprising an early warning unit, c h a r a cte rised in that the early warning unit determines whether that there is a risk of communication disruption based on a combination of a comparison between an estimation of the SINR and a predetermined first threshold and a comparison between the time derivative of said estimated SINR and a predetermined second threshold, said early warning unit comprising a signal processing unit that decodes the received signal, remodulates it and subtracts the remodulated signal from the received signal, thereby creating a residual, said early warning unit further compris- ing an analysis unit that estimates, based on an estimation of the SINR, thermal noise power according to the system specification, the residual and the position of the terminal, interference signal power and classifies, using a classification algorithm, the type of interference as unintentional/intentional or co-channel interfer- ence, and that the early warning unit generates a proactive warning to the user of the terminal when a risk of communication disruption has been established, said warning including information about the type of noise and interference.
    [2] 2. A digital radio terminal according to claim 1, characterised in that said early warning comprises noise added to the audio signal, said noise increasing in strength with increased determined risk of communication disruption to emulate the degradation of the communication channel of an analog radio system.
    [3] 3. A digital radio terminal according to claim 1 or 2, characterised in that the signal processing unit estimates the SINR as the remodulated signal power divided by the residual signal power.
    [4] 4. A digital radio terminal according to anyone of claims 1-3, characterised in that the classification algorithm uses curtosis estimation in higher order statistics
    [5] 5. A digital radio terminal according to anyone of claims 1-4, c h a r a cterised in that said early warning comprises a status message informing the user of the probable cause of the problem including the information about the type of noise and interference and the estimation of the SINR. 9
    [6] 6. A digital radio terminal according to claim 5, cha r a cterised in that the status message, completed with information of the position of the terminal, is sent for reception through-out a radio network to which the terminal is connected, the terminal being adapted to receive corresponding information from said network.
    [7] 7. A digital radio terminal according to anyone of claims 1-6, ch a r a cterised in that the terminal is provided with at least two antenna elements and that said analysis unit determines that there is an intentional jammer by studying the covariance of the residual signal from said at least two antenna elements.
    [8] 8. A digital radio system comprising a network of digital radio terminals according to claim 6 or 7, ch a r a cterised in that the system incorporates a command and control unit that is designed to exchange information with the terminals, said command and control unit receiving the status messages from said terminals, and based on this take counter-actions, such as change of frequency or change of physical position for a single terminal, a group of terminals or all terminals in the network.
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    同族专利:
    公开号 | 公开日
    SE537105C2|2015-01-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2016-03-01| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    SE1100556A|SE537105C2|2011-07-21|2011-07-21|A digital radio terminal comprising an early warning device and a digital radio system comprising such terminals|SE1100556A| SE537105C2|2011-07-21|2011-07-21|A digital radio terminal comprising an early warning device and a digital radio system comprising such terminals|
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