Method for radio measuring applications

Abstract

A method for radio measuring applications, wherein at least a first radio node operates as an initiator and at least a second radio node as a transponder, in a first step a first carrier frequency is transmitted by the initiator as an initial signal and received by the transponder. In a second step a response signal with a second carrier frequency is transmitted by the transponder and received by the initiator, during a measurement cycle at least one step sequence of the first and the second step is performed. First the first steps of all sequence of steps and subsequently at least a portion of the second steps of the step sequences are performed in succession, the first carrier frequency assumes a value within a predetermined frequency domain for each repetition, and the initial signals and the response signals are mutually coherent at least within the measurement cycle.

Claims

1. A method for radio measuring applications, the method comprising: operating a first radio node of at least two radio nodes as an initiator and operating a second radio node of the at least two radio nodes as a transponder, each of the first and second radio nodes has its own timer and a data interface, and there is a time offset between the timers of the first and second radio nodes; transmitting, in a first step, by the initiator an initial signal with a first carrier frequency, the initial signal being received by the transponder during a first reception period as a received initial signal; transmitting, in a second step, by the transponder a response signal with a second carrier frequency and the initiator receives the response signal during a second reception period as a received response signal, the first step and the second step forming a step sequence; performing, during a measurement cycle, one or more step sequences; performing first, the first steps of all step sequences and subsequently, the second steps of at least a portion of the step sequences in succession; assuming, for each repetition of the step sequence, by the first carrier frequency of the initial signal, a predetermined value within a predetermined frequency domain, the initial signals and the response signals of all step sequences being mutually coherent at least during the measurement cycle; and operating the method operates either in a first mode or in a second mode, wherein, in the first mode, the response signal is formed from at least a portion of the received initial signal and a transfer function and / or the time offset are determined on the basis of at least a portion of the received response signals, wherein, in the second mode, the response signal is formed independently from the received initial signal, at least one received initial signal is transmitted via the data interface and at least one transfer function and / or the time offsets are determined on the basis of at least portion of the received response signals and at least a portion of the received and transmitted initial signals, and wherein, within each step sequence, the second carrier frequency corresponds to the first carrier frequency or differs from the first carrier frequency.

2. The method according to claim 1, wherein the first steps of the step sequences during the measurement cycle are performed according to a first sequence and the second steps of the step sequences according to the first sequence or in a sequence which is reverse to the first sequence.

3. The method according to claim 1, wherein during a measurement cycle, the second steps of all step sequences are performed.

4. The method according to claim 1, wherein a first complex signal vector is determined from the received initial signal and the response signal is formed from the first complex signal vector or a reciprocal first complex signal vector or a conjugate complex first complex signal vector.

5. The method according to claim 1, wherein a first phase is determined from the received initial signal and the response signal is formed from the first phase or from an inverted first phase.

6. The method according to claim 1, wherein each of the first and second radio node operates over several step sequences at least once as an initiator and at least once as a transponder or each of the first and second radio node operates over several step sequences only as an initiator or only as a transponder.

7. The method according to claim 1, wherein, on the basis of the determined transfer function and / or the time offset, a distance between the one initiator and the one transponder is determined.

8. The method according to claim 1, wherein for at least one determined transfer function, a multipath analysis is carried out.

9. The method according to claim 1, wherein a filter is applied to the received response signals and / or the received initial signals.

10. The method according to claim 1, wherein, with each repetition of the step sequence, an amplitude and / or a phase of the initial signal is changed in addition to the carrier frequency of the initial signal.

11. The method according to claim 1, wherein the initiator transmits the initial signal during a first transmission period and the transponder transmits the response signal during a second transmission period, and wherein the first transmission period and the second transmission period each comprise a plurality of successive time windows, in each of the first and second transmission periods, transmissions are made only during the time windows and in each of the first and second transmission periods, two successive time windows follow one another immediately in time or are offset in time to each other.

12. A system, comprising: an initiator radio node and a transponder radio node, each of the initiator and transponder radio nodes having its own timer and a data interface, and there being a time offset between the timers of the initiator and transponder radio nodes, wherein the initiator and the transponder radio nodes are configured to perform one or more step sequences during a measurement cycle, each step sequence comprising first and second steps, wherein in the first step, the initiator radio node is configured to transmit an initial signal with a first carrier frequency, the initial signal being received by the transponder radio node during a first reception period as a received initial signal, wherein in the second step, the transponder radio node is configured to transmit a response signal with a second carrier frequency, the response signal being received by the initiator radio node as a received response signal, wherein the first steps of all of the one or more step sequences and the second steps of at least a portion of the one or more step sequences are performed in succession, wherein for each repetition of the step sequence, the first carrier frequency of the initial signal is a predetermined value within a predetermined frequency domain, the initial signals and the response signals of all step sequences being mutually coherent during the measurement cycle, wherein the initiator and the transponder radio nodes operate either in a first mode or in a second mode, wherein in the first mode, the response signal is formed from at least a portion of the received initial signal and a transfer function and / or the time offset are determined on the basis of at least a portion of the received response signals, wherein in the second mode, the response signal is formed independently from the received initial signal, at least one received initial signal is transmitted via the data interface and at least one transfer function and / or the time offsets are determined on the basis of at least portion of the received response signals and at least a portion of the received and transmitted initial signals, and wherein, within each step sequence, the second carrier frequency corresponds to the first carrier frequency or differs from the first carrier frequency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 is a schematic measurement arrangement for performing an inventive method for radio measuring applications in accordance with an exemplary embodiment,

(3) FIG. 2 is a flow chart of the exemplary embodiment of the method for radio measuring applications,

(4) FIG. 3 is a diagram of the temporal course of the method for radio measuring applications according to exemplary embodiment, and

(5) FIG. 4 is a schematic measurement arrangement for performing the inventive method for radio measuring applications in accordance with an exemplary.

DETAILED DESCRIPTION

(6) The illustration in FIG. 1 shows a diagram of an arrangement of two radio nodes for radio measuring applications, wherein the arrangement is designed to run a first mode of the inventive method.

(7) A first radio node FI, called the initiator, and a second radio node FT, called the transponder, are provided. The initiator FI and the transponder FT each have a receiving unit RX, a transmitting unit TX, a data interface DS1 or DS2 and their own timer Z(t) or Z(t′).

(8) The data interfaces DS1 and DS2 are designed as a communication protocol for wireless data exchange. There is a time offset T.sub.offs between the first timer Z(t) of the first radio node FI and the second timer Z(t′) of the second radio node. The timers are each formed as crystal oscillators.

(9) The initiator FI is designed to transmit an initial signal T.sub.I during a first step S1 by means of the transmitting unit TX over a propagation medium PM, for example air. The transponder FT is designed to receive the initial signal T.sub.I transmitted by the initiator F.sub.I during the first step S1 as a received initial signal R.sub.T after transmission over the propagation medium PM.

(10) In addition, the transponder FT is designed to determine a signal vector V.sub.T from the received initial signal R.sub.T using a function F (R.sub.T, . . . ) and to exchange it by means of the data interface DS2.

(11) In order to be able to execute the first mode of the method according to the invention, the transponder FT is additionally designed to provide the signal vector V.sub.T to the transmitting unit TX and to process it further by means of the transmitting unit TX.

(12) During a second step S2, the transponder FT transmits a response signal T.sub.T by means of the transmitting unit TX. During the second step S2, by means of the receiving unit RX, the initiator FI receives the response signal T.sub.T emitted by the transponder after transmission over the propagation medium PM as the received response signal R.sub.I.

(13) Moreover, the initiator FI is designed to determine the signal vector V.sub.I from the received signal R.sub.I using the function H(R.sub.I, . . . ) and to exchange it with the data interface DS1.

(14) The influence of the transmission over the propagation medium PM on the transmitted signals is referred to as transfer function G.

(15) A method sequence according to the first alternative embodiment of the method for radio measuring applications is explained in more detail below with reference to FIGS. 2 and 3.

(16) As shown in FIG. 2, both radio nodes FI and FT each have a generator, an upward mixer which converts a complex signal vector VT or VI from the baseband to the HF position, a downward mixer which converts a high-frequency signal to a signal vector in the baseband, and a time and frequency control ZFS1 or ZFS2 containing the timer Z (t) or Z (t′), which controls all system changes of state in a fixed time regime.

(17) The time and frequency control ZFS1 or ZFS2 works on the basis of a time unit T.sub.MU and ensures that all relevant changes of state (sampling of the signal vectors, RX/TX-TX/RX transitions, frequency changes) are firmly connected with the time base specified by the respective timer and can be related to this.

(18) The time and frequency control ZFS1 or ZFS2 is also responsible for ensuring that the coherence between the signals and vectors is maintained over the required length, i.e., that settling times are taken into account and all the functional units, even in the transition regions, are located in the linear control ranges (such as a frequency synthesizer, PLL). The radio nodes FI and FT are controlled by the time and frequency control ZFS1 and ZFS2 during the step sequence of steps S1 and S2.

(19) The step sequence also includes the transition regions (step delay), which are shown as delay elements of the value T.sub.SVS. The time and frequency control ZFS1 or ZFS2 also controls the frequency ω.sub.p over an available frequency domain.

(20) As a result, the time and frequency control ZFS1 and ZFS2 each generate a phase-coherent domain PD, in which the high-frequency synthesis, the generation of the corresponding transmit vectors and the extraction of the receive vectors are in a fixed relationship to one another on the live end.

(21) Furthermore, each radio node has a logic unit which supplies the signal vectors V.sub.T or V.sub.I for generating the corresponding transmission signal T.sub.I (m, n) or T.sub.T (m, n) by using a function F or H based on input parameters (such as the received signal vectors R.sub.I (m, n) and R.sub.T (m, n) and/or the parameters provided via the data interface DS1 or DS2).

(22) In the drawings, n indicates the index within a sequences of steps, which overall has a duration of T.sub.SF=n.sub.max*T.sub.MU. The index has a range of values n=0,1, . . . (n.sub.max−1), wherein n.sub.max is determined by the specific design of the measurement cycle and in the present example, n.sub.max=8 was selected. In connection with the measurement unit time T.sub.MU, n provides the basis for a discrete-time system on the basis of t=n*T.sub.MU+m*T.sub.SF. Here, m indicates the index of the sequence of steps within the measurement cycle with m=1, 2 . . . (m.sub.max). m.sub.max is determined by the specific embodiment and is, inter alia, dependent on the number of frequencies for which the transfer function is to be determined. A series of step sequences is referred to as the measurement cycle. A measurement cycle has a length of at least T.sub.Z=m.sub.max*T.sub.SF. To differentiate between initiator radio node FI and transponder radio node FT, the corresponding values of the transponder are indicated by markings (for example, frequencies and times of the f′.sub.p, ω′.sub.p, t′, . . . ).

(23) As illustrated in FIGS. 2 and 3, in the initiator FI and in the transponder FT, the frequency generator first generates a signal of the frequency f.sub.p, f.sub.p′ or ω.sub.p=2π*f.sub.p, ω′.sub.p=2π*f′.sub.p with (p=1), wherein the signal of the frequency generator of the transponder is delayed by the time offset T.sub.offs and has a static phase offset Δφ. For the purposes of the further explanation, these frequencies are considered equally great. It is assumed that corresponding frequency offset corrections (if necessary) have already been carried out or that the necessary parameters have already been extracted to correct the receive vectors accordingly. Thus, for the other statements, f.sub.p=f.sub.p′ is assumed, wherein the method also includes frequency differences f.sub.p=f.sub.p′+Δf′, if Δf is known, for example, has been provided by the receiving architecture.

(24) The method comprises a plurality of step sequences from a first step S1 and a second step S2, wherein with each repetition of the step sequence, the carrier frequencies ω.sub.p and ω′.sub.p are selected within a predetermined frequency domain according to the corresponding requirements. In the exemplary embodiment shown, the second carrier frequency ω′.sub.p corresponds to the first carrier frequency ω.sub.p.

(25) The multiple repetitions of the sequence of steps form a measurement cycle. According to the invention, in each measurement cycle first all the first steps S1 are performed successively, then the second steps S2 of the step sequences of the measurement cycle are performed.

(26) In a first step S1 m=1, n=0,1,2,3 p=1 of a first step sequence, the initiator FI uses a mixer and the frequency generator to generate a signal T.sub.I (m, n) with a first carrier frequency ω.sub.p with a signal vector V.sub.I (m, n) and couples it out into the propagation medium PM as initial signal T.sub.I (m, n). To illustrate, the signal vector is T.sub.I (m, n)=1, i.e., the initiator radio node transmits a reference signal with a carrier frequency ω.sub.p as the initial signal T.sub.I.

(27) It is understood that the above-described does not exclude the signal vectors V.sub.I or V.sub.T from being brought to an intermediate frequency IF before coupling out in a further mixer by multiplication with a subcarrier, often referred to as a local oscillator, before the signal is finally converted to the actual target frequency ωp.

(28) During a first reception period in the step S1 with m=0, n=0,1,2, 3, the transponder FT determines a received initial signal R.sub.T (m, n) by mixing the received HF signal with the signal of the frequency generator of the frequency f′.sub.p, which is shifted/offset in time by Toffs with respect to the generator signal of the initiator.

(29) The position of the received initial signal R.sub.T (m, n) in the complex plane is determined by the internal time reference or by the second timer Z(t′) with t′=n*T′.sub.MU +m*T′.sub.SF of the transponder FT and with respect to the initiator is determined by the transfer function of the radio channel on the frequency f.sub.p and the time offset and phase offset T.sub.offs or Δφ between the timers. In the context of the method, T.sub.MU=T′.sub.MU, T.sub.SF=T′.sub.SF, T.sub.Z=T′.sub.z, and so on. Based on the received initial signal R.sub.T (m, n), a signal vector V.sub.T (m, n+4)=F (R.sub.T (m, n), . . . ) is formed and transmitted as signal vector V.sub.T to the transmitting unit TX of the transponder FT.

(30) The transponder also forms a discrete-time system with t′=n*T′.sub.MU+m*T′.sub.ASF.

(31) In a further first step S1 m=2, n=0,1,2,3 p=2 of a second step sequence, the initiator FI uses a mixer and the frequency generator to generate a signal T.sub.I (m, n) with a first carrier frequency w.sub.p (p=2) with a signal vector V.sub.I (m, n) and couples it out into the propagation medium PM as initial signal T.sub.I (m, n), and in a further step S1 with m=2, n=0,1,2,3 p=2, during a reception period the transponder determines a received initial signal R.sub.T (m, n) by mixing the received HF signal with the signal of the frequency generator of the frequency f′.sub.p, which is displaced in time by Toffs relative to the generator signal of the initiator.

(32) Accordingly, in the embodiment shown, a further first step S1 with m=3, n=0,1,2,3 and p=3 of a third step sequence is performed.

(33) Subsequently, the second steps of the three step sequences are performed in reverse order.

(34) In a second step S2 m=3, n=4,5,6,7 and p=3 of the third step sequence, a transmit signal T.sub.T (m, n) with the frequency f′.sub.p is generated by the transponder FT from the determined baseband vector V.sub.T (m, n) using a mixer and the frequency generator and is coupled out as a response signal T.sub.T into the propagation medium PM.

(35) The response signal T.sub.T m=3,n=4,5,6,7 is obtained from the received initial signal R.sub.T (m, n) m=3, n=0,1,2,3 using the function F(R.sup.T (m, n), . . . ) and thus formed at least from a portion of the received initial signal R.sub.T.

(36) During a reception period during the second step m=3, n=4,5,6,7of the third step sequence, the initiator FI determines a received response signal R.sub.I (m, n), . . . ) with m=3, n=4,5,6,7, wherein the position of the received response signal R.sub.I with respect to the internal time reference of the initiator FI or the first timer Z(t) is evaluated with the time t=n*T.sub.MU+m*T.sub.SF. To this end, the received HF signal of the frequency f′.sub.p is converted to the baseband using a mixer and the signal of the frequency generator of the frequency f.sub.p.

(37) The corresponding discrete-time values for the initiator result from t=n*T.sub.MU+m*T.sub.SF and for the transponder from t′=n*T′.sub.MU+m*T′.sub.SF.

(38) The second steps S2 with m=2, n=4,5,6,7 and p=2 of the further step sequence as well as the second step S2 with m=1, n=4,5,6,7 and p=1 of the first step sequence are subsequently performed accordingly.

(39) By transmitting information about the received initial signal T.sub.I using the response signal T.sub.T, it is possible to directly determine a transfer function for the circulation (step sequence from step S1 and step S2) and/or a time offset on the basis of the received response signals T.sub.T.

(40) In order to ensure a coherence of all initial signals T.sub.I and response signals T.sub.T during a measurement cycle, the initiator FI and the transponder FT each include a coherent time and frequency control, wherein a rough time synchronization, for example by exchanging data frames via the data interfaces DS1 and DS2, takes place.

(41) The temporal course of the method is outlined in particular in FIG. 3. Above the time axes t and t′=t+T.sub.offs, the profile of the frequencies ω.sub.p and ω′.sub.p, an action of the transmitting units TX of the transponder FT and of the initiator FI, an action of the receiving units RX of the transponder FT and of the initiator FI over three sequences of steps m=1 to m=3 are shown.

(42) In addition, the activities of the transponder FT and the initiator FI are shown as vertically extending bars, with bold bars each indicating the switching from reception mode to transmission mode or from transmission mode to reception mode, thin bars with squares each indicating the transmission of a signal within a transmission time window and arrows indicating the reception of a signal.

(43) Between each transmission action and the subsequent reception action or vice versa, there is always a step delay. Thereby, influences or disruptions due to the settling process of the radio nodes are prevented. The step delay is correspondingly greater than a settling time of the respective nodes. At the same time, it should be noted that the presented relations assume a settled steady state. This condition is met only for portions of the step delay, which are delimited by transition regions in which the corresponding settling states take place. In these, the corresponding signal vectors can only be used to a limited extent in the context of the method. In the present case, this relates to the vectors R.sub.I,T (m, n) with n=0,.4.

(44) At least one valid receive vector per radio node per step of each step sequence is required for implementing the method in the sense described above.

(45) The embodiment shown in FIG. 3 has transmission and reception periods, having a plurality of separate transmitting and receiving time windows. If one assumes a symmetrical distribution between the initiator FI and the transponder FT, the corresponding continuous-time transmission signals T.sub.I and T.sub.T with their values at the times t=n*T.sub.MU+m*T.sub.SF and t′=n*T′.sub.MU+m*T′.sub.SF oppose the corresponding number of reception time windows on the other side and thus allow for the determination of the associated receive vectors R.sub.T and R.sub.I.

(46) The time windows thus available can be used for different purposes. Here is a selection: Transmission of the reference phase of the transponder; Signaling between initiator and transponder (amplification and transmission power adjustments, . . . , encryption); Noise suppression by averaging a plurality of receive vectors, which were generated on the basis of a transmit vector of the opposite side; Assignment to different antennas to produce space diversity for determining angles of incidence in particular and for improving measurement accuracy in general (beam steering, MIMO, Smart Antenna); and/or For the detection of channel assignments in terms of LBT (Listen-before-Talk), CS (Carrier Sense) and DAA (Detect and Avoid) requirements for the approval of radio systems.

(47) When dimensioning, both the respective settling processes and the maximum time offset fluctuations achievable by the rough synchronization should be considered, and the guard interval step delay or settling time should be designed accordingly.

(48) FIGS. 3 shows the inventive method in accordance with a first embodiment of mode 2. The differences from the previous figures are explained below.

(49) FIG. 4 shows a schematic arrangement of the initiator FI and the transponder FT in mode 2.

(50) Each first step S1 is initially performed in the same way as in mode 1. During the second step S2, the transponder FT is configured to generate the response signal T.sub.T by means of the transmitting unit TX, wherein the baseband vector V.sub.T to V.sub.T (m, n)=1 is selected for the generation of the response signal T.sub.T. This means that the transponder transmits a signal T.sub.T that only depends on its own time reference and is therefore independent from the initiator transmission signal T.sub.I or the receive signal vector R.sub.T determined therefrom.

(51) The transponder FT is additionally adapted to at least partially transmit the received initial signal R.sub.T determined in the first steps S1 to the initiator by means of the data interface DS2.

(52) The initiator FI is additionally adapted to receive the receive signals R.sub.T via the data interface DS1 and to determine the time offset T.sub.offs based on at least a portion of the received receive signals R.sub.T and the determined measurement vectors R.sub.I.

(53) Based on the time offset T.sub.offs and at least a portion of the receive signals R.sub.I received by the initiator FI, a transfer function for the radio channel between the transponder FT and the initiator FI can then be determined. It is thus possible to directly determine the transfer function for a single route between initiator and transponder and not for a two-way cycle.

(54) The motivation of the one-way channel transfer function G.sub.1WR (jω)=G (jω) as compared to the widespread determination of the two-way channel transfer function G.sub.2WR (jω)=G.sup.2 (jω) will be explained.

(55) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.