RADAR SYSTEM, A RADAR ARRANGEMENT, AND A RADAR METHOD FOR CONCURRENT RADAR OPERATIONS

Abstract

It is described a radar system (100), comprising: i) a transmitter (120) configured to: provide a code (C), identify a plurality of regions (R) within the code (C), apply a transmitter-specific cyclic shift scheme to the plurality of regions (R), generate a signal (S) from the code (C) and transmit the signal; and ii) a receiver (130), configured to: receive an echo (E) of the signal (S), and identify the transmitter (120) based on the transmitter-specific cyclic shift scheme.

Further, a radar arrangement and a method of performing a radar operation are described.

Claims

1. A radar system, comprising: a transmitter configured to: provide a code, identify a plurality of regions within the code, apply a transmitter-specific cyclic shift scheme to the plurality of regions, generate a signal from the code and transmit the signal; and a receiver, configured to: receive an echo of the signal, and identify the transmitter based on the transmitter-specific cyclic shift scheme.

2. The radar system according to claim 1, wherein the transmitter-specific cyclic shift scheme comprises arranging the regions of the code in a specific order, thereby providing a time offset to the regions.

3. The radar system according to claim 1, wherein the code comprises a sequence of code symbols, and wherein at least some of the plurality of regions are within at least one of the code symbols.

4. The radar system according to claim 1, further comprising: a target, wherein each region of the plurality of regions is longer than the distance between the transmitter and the target.

5. The radar system according to claim 1, wherein the radar system is implemented as one of a monostatic radar application, a multi-static radar application, a statistical MIMO application, a coherent MIMO application.

6. The radar system according to claim 1, further comprising at least one of the following features: wherein the transmitter and the receiver apply the same transmitter-specific cyclic shift scheme or a different cyclic shift scheme; wherein the radar system is a pulse radar system; wherein the radar system is configured for transmitting and receiving ultra-wide band, UWB, signals, and echoes thereof; wherein a code symbol encodes a plurality of bits using a digital modulation scheme; wherein the code is at least partially configured as a training sequence which comprises a cyclic training sequence; wherein the plurality of regions comprise at least one of: a first code segment at a code position before the cyclic training sequence, a second code segment at a code position after the cyclic training sequence.

7. The radar system according to claim 1, wherein the code comprises auto-correlation properties that are more pronounced than cross-correlation properties.

8. A radar arrangement, comprising: a radar system according to claim 1; a further transmitter configured to provide a further code, identify a further plurality of regions within the further code, apply a further transmitter-specific cyclic shift scheme to the further plurality of regions, generate a further signal from the further code and transmit the further signal; and a further receiver, configured to receive at least one of: the echo of the signal, an echo of the further signal, and identify at least one of: the transmitter based on the transmitter-specific cyclic shift scheme, the further transmitter based on the further transmitter-specific cyclic shift scheme.

9. The radar arrangement according to claim 8, comprising at least one of the following features: wherein the transmitter-specific cyclic shift scheme is different from the further transmitter-specific cyclic shift scheme; wherein the plurality of regions and the further plurality of regions are similar or different.

10. The radar arrangement according to claim 8, wherein the transmitter and the further transmitter are synchronized.

11. The radar arrangement according to claim 8, wherein the radar arrangement is implemented as a one of the group which consists of a monostatic radar application, a multi-static radar application, a statistical MIMO application, a coherent MIMO application.

12. A method of performing a radar operation including a plurality of transmitters and receivers, the method comprising: generating a code; identifying a plurality of regions R within the code; applying a transmitter-specific cyclic shift scheme to the plurality of regions; generating a signal from the code and transmitting the signal; receiving an echo of the signal; and identifying a specific transmitter based on the transmitter-specific cyclic shift scheme.

13. The method according to claim 12, further comprising at least one of the following steps: exchanging the transmitter-specific cyclic shift scheme within a transmitter-receiver pair; broadcasting the transmitter-specific cyclic shift scheme to at least one of a transmitter and a receiver.

14. The method according to claim 12, further comprising: updating the transmitter-specific cyclic shift scheme.

15. The method according to claim 14, wherein updating comprises changing the cyclic shift in a pseudo-random manner.

16. The radar system according to claim 2, wherein the code comprises a sequence of code symbols, and wherein at least some of the plurality of regions are within at least one of the code symbols.

17. The radar system according to claim 2, further comprising: a target, wherein each region of the plurality of regions is longer than the distance between the transmitter and the target.

18. The radar system according to claim 2, wherein the radar system is implemented as one of a monostatic radar application, a multi-static radar application, a statistical MIMO application, a coherent MIMO application.

19. The radar system according to claim 2, further comprising at least one of the following features: wherein the transmitter and the receiver apply the same transmitter-specific cyclic shift scheme or a different cyclic shift scheme; wherein the radar system is a pulse radar system; wherein the radar system is configured for transmitting and receiving ultra-wide band, UWB, signals, and echoes thereof; wherein a code symbol encodes a plurality of bits using a digital modulation scheme; wherein the code is at least partially configured as a training sequence which comprises a cyclic training sequence; wherein the plurality of regions comprise at least one of: a first code segment at a code position before the cyclic training sequence, a second code segment at a code position after the cyclic training sequence.

20. The radar system according to claim 2, wherein the code comprises auto-correlation properties that are more pronounced than cross-correlation properties.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 illustrates a radar system according to an exemplary embodiment of the present disclosure.

[0041] FIG. 2 illustrates code sequences with cyclic shifted regions according to an exemplary embodiment of the present disclosure.

[0042] FIG. 3 illustrates a radar arrangement implemented as a mono-static application according to an exemplary embodiment of the present disclosure.

[0043] FIG. 4 illustrates a radar arrangement implemented as a multi-static application according to an exemplary embodiment of the present disclosure.

[0044] FIG. 5 illustrates a radar arrangement implemented as a statistical MIMO application according to an exemplary embodiment of the present disclosure.

[0045] FIG. 6 illustrates a radar arrangement implemented as a coherent MIMO application according to an exemplary embodiment of the present disclosure.

[0046] FIG. 7 illustrates training sequences for radar applications according to exemplary embodiments of the present disclosure.

[0047] FIG. 8 illustrates a scrambled training sequence in more detail.

[0048] FIG. 9 illustrates a cyclic training sequence in more detail.

[0049] The illustrations in the drawings are schematic. In different drawings, similar or identical elements are provided with the same reference signs.

DESCRIPTION OF THE DRAWINGS

[0050] Before, referring to the drawings, exemplary embodiments will be described in further detail, some basic considerations will be summarized based on which exemplary embodiments of the present disclosure have been developed.

[0051] According to exemplary embodiments of the present disclosure, orthogonality between multiple radar transmitter signals, received at a receiver, is achieved by assigning a code symbol with ideal autocorrelation properties to each transmitter with a different cyclic shift, thereby separating the codes from each transmitter to the receiver via a time-offset (cyclic shift). The present disclosure elegantly and efficiently solves the interference issue, in particular for time synchronized UWB devices.

[0052] According to exemplary embodiments of the present disclosure, key features can include: [0053] using code symbol(s) with pronounced/ideal autocorrelation properties, [0054] assigning to each transmitter a cyclic shifted version of at least one code symbol, [0055] operating the devices (transmitters) in a time synchronized manner, [0056] defining a cyclic shift that is large enough, such that the CIR responses do not overlap, [0057] the receivers can either correlate with the original code symbol or the cyclically shifted version of the code symbol, [0058] the receivers can separate the CIRs to each transmitter by a time-offset corresponding to the cyclic shift to these transmitters.

[0059] FIG. 1 is a schematic illustration of a radar system 100 according to an exemplary embodiment of the present disclosure. The radar system 100 comprises a transmitter 120 with a control unit 110 which is configured for generating a code C. A plurality of regions R are identified within the code C, and a transmitter-specific cyclic shift scheme is applied to the plurality of regions (see FIG. 2 below for details). The transmitter 120 is configured for generating a signal S from the code C, and further configured for transmitting the signal S via an antenna 111. The radar system 100 further comprises a receiver 130, configured for receiving an echo E of the signal S via a further antenna 112. Hereby, the signal S is reflected from a target 150 (object of interest) as the echo E. After receiving, the receiver 130 identifies the transmitter 120 based on the transmitter-specific cyclic shift scheme. The receiver 130 can be associated with a correlator 140, configured for correlating the code C′ of the received echo E with a code template. The radar system 100 is further configured, as is exemplary shown in FIG. 1, to produce an output signal (in particular a correlator output O), which may, for example, be a visual output, or in general, any digital or analogue output for further processing. For example, once the echo E has been received, it may be demodulated, e.g. by a higher order digital modulation method according to exemplary embodiments.

[0060] FIG. 2 illustrates code sequences with cyclic shifted regions according to an exemplary embodiment of the present disclosure. There are shown three codes C for a first transmitter 120, a second transmitter 160, and a third transmitter 180, respectively (number N of transmitters=3). Each code comprises a code symbol within a code sequence, wherein the code symbol encodes a plurality of bits (in this example, the code length L is 91 bits). The code symbol is identical for all three transmitters 120, 160, 180, nevertheless, a plurality of regions R have been identified within the code C, and a transmitter-specific cyclic shift scheme has been applied to the plurality of regions R. The cyclic shift scheme results in a re-arrangement of the regions (change of time offset) that is different (transmitter-specific) for each of the transmitters 120, 160, 180. Corresponding receivers 130, 170, 190 can thereby clearly identify each transmitter 120, 160, 180 based on the transmitter-specific cyclic shift schemes.

[0061] FIGS. 3 to 6 respectively illustrate a radar arrangement 200 according to an exemplary embodiment of the present disclosure. The radar arrangement 200 comprises a radar system 100 as described for FIG. 1 and two further radar systems, each comprising:

i) a further transmitter 160, 180 configured to provide a further code (can be similar to the code), identify a further plurality of regions within the further code, apply a further transmitter-specific cyclic shift scheme to the further plurality of regions, generate a further signal from the further code and transmit the further signal, and
ii) a further receiver 170, 190, configured to receive the echo of the signal and/or an echo of the further signal, and identify at least one transmitter 120, 160, 180 based on the transmitter-specific cyclic shift scheme.

[0062] FIG. 3 illustrates a radar arrangement 200 according to an exemplary embodiment of the present disclosure implemented as a mono-static application. There are three monostatic radar devices (each comprising a transmitter and a receiver) in concurrent operation. To each device (transmitter/receiver pair), there is assigned a different transmitter-specific cyclic shift scheme, whereby, in this example, the transmitter and the receiver of each device uses the same transmitter-specific cyclic shift scheme. The mono-static devices are only interested in their own echo signal, and interferences can be avoided by the different transmitter-specific cyclic shift schemes.

[0063] FIG. 4 illustrates a radar arrangement 200 implemented as a multi-static application according to an exemplary embodiment of the present disclosure. The multi-static application uses distributed transmitters and receivers to obtain different viewing aspect of the target 150. There are three transmitter devices 120, 160, 180 and three receiver devices 130, 170, 190 being spatially separated. To each transmitter device 120, 160, 180, there is assigned a different transmitter-specific cyclic shift scheme. The receiver devices 130, 170, 190 can either use any of the transmitter-specific cyclic shift schemes or all receiver devices 130, 170, 190 can use the same cyclic shift scheme. Each receiver 130, 170, 190 can receive the echo, separate, and identify the different transmitter-specific cyclic shift schemes of each transmitter device 120, 160, 180.

[0064] FIG. 5 illustrates a radar arrangement implemented as a statistical MIMO application according to an exemplary embodiment of the present disclosure. The statistical MIMO application uses combined transmitter-receiver (pairs) on the target to obtain additional information. There are three radar devices (each comprising a transmitter and a receiver) in concurrent operation. To each device (transmitter/receiver pair), there is assigned a different transmitter-specific cyclic shift scheme. Each receiver 130, 170, 190 can separate the echo from each transmitter 120, 160, 180 based on the transmitter-specific cyclic shift scheme.

[0065] FIG. 6 illustrates a radar arrangement implemented as a coherent MIMO (Virtual Array MIMO) application according to an exemplary embodiment of the present disclosure. The coherent MIMO application uses closely located transmitter-receivers (same viewing aspect of target 150) to enable calculation of virtual array antennas. There are three transmitter devices 120, 160, 180 and three receiver devices 130, 170, 190 being spatially separated. To each transmitter device 120, 160, 180, there is assigned a different transmitter-specific cyclic shift scheme. The receiver devices 130, 170, 190 can either use any of the transmitter-specific cyclic shift schemes or all receiver devices 130, 170, 190 can use the same cyclic shift scheme. Each receiver 130, 170, 190 can separate the echo from each transmitter 120, 160, 180 based on the transmitter-specific cyclic shift scheme.

[0066] FIG. 7 illustrates scrambled training sequences (STS) for ranging applications according to the IEEE 15.4z standard, which is modified according to an exemplary embodiment of the present disclosure. The sequences are arranged as packets and FIG. 7 shows four packet configurations. In this exemplary example, the HRP-ERDEV PPDU format with RMARKER position is applied. Besides the sequences “SYNC”, “SFD”, “PHR”, and “PHY Payload”, the packets can comprise the actual scrambled training sequence. In the first configuration (specifier 0), there is no STS field included in the PPDU. In the second configuration (1), the STS field is placed immediately after the SFD field and before the PHR field. In the third configuration (2), the STS field is placed after the PHY payload field. In the fourth configuration (3), the STS field is placed immediately after the SFD field and no PHR or data fields are included. Now, according to an exemplary embodiment of the present disclosure, the STS is substituted by a cyclic training sequence (CTS) that applies the described transmitter-specific cyclic-shift scheme (the plurality of regions are indicated as R, each packet can be seen as a code C). A further packet configuration may comprise only the CTS sequence.

[0067] FIG. 8 illustrates the above described scrambled training sequence in more detail, i.e. there are gaps arranged between each active STS segment. In an exemplary embodiment of the present disclosure, at least one STS segment is substituted by a cyclically shifted CTS segment.

[0068] FIG. 9 illustrates the above described cyclic training sequence in more detail. The CTS segment (can be seen as code C) consists of three parts: i) a gap at the beginning and the end, ii) a cyclic prefix (at the beginning) with a repetition of the last N (a PHY PIB attribute in this example) chips of a sequence (at the end), and iii) a CTS sequence which is cyclically shifted by M (a PHY PIB attribute in this example)*N chips. In a specific embodiment of the present disclosure, the cyclic prefix segment and the “last N chips” segment are treated as a plurality of regions of code C and are re-arranged using a (transmitter-specific) cyclic-shift scheme.

[0069] In this specification, embodiments have been presented in terms of a selected set of details. However, a person of ordinary skill in the art would understand that many other embodiments may be practiced which include a different selected set of these details. It is intended that the following claims cover all possible embodiments.

REFERENCE NUMERALS

[0070] C Code to be transmitted [0071] C′ Received code [0072] E Echo [0073] O Output [0074] R Region [0075] S Signal [0076] 100 Radar system [0077] 110 Control unit [0078] 111 Antenna [0079] 112 Further antenna [0080] 120 Transmitter [0081] 130 Receiver [0082] 140 Correlator [0083] 150 Target [0084] 160 Further (second) transmitter [0085] 170 Further (second) transmitter [0086] 180 Third transmitter [0087] 190 Third receiver [0088] 200 Radar arrangement