Patent ID: 12231273

It should be noted that the Figures are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these Figures have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in modified and different embodiments

DETAILED DESCRIPTION OF EMBODIMENTS

FIG.1shows a mobile communication base station100including a baseband processor140and a digital front-end150for a single channel according to an embodiment. The baseband processor140includes a carrier mapping-demapping module120, a controller110, a frequency-to-time and cyclic prefix addition module112, a time-to-frequency and cyclic prefix recovery module114, and a sense module130. The digital front-end150includes a digital to analog converter (DAC)118, and an analog to digital converter (ADC)124. In some example base stations using digital beam forming, the frequency-to-time and cyclic prefix addition module112, time-to-frequency and cyclic prefix recovery module114, digital to analog converter (DAC)118, and an analog to digital converter (ADC)124may be shared with other channels (not shown).

The controller110may have a mode control output134connected to the carrier mapping-demapping module120and the sense module130and other modules as appropriate (not shown). The carrier mapping-demapping module120may have a connection102which can receive and transmit orthogonal frequency division multiplexing (OFDM) symbols. Carrier mapping-demapping module120may have a carrier mapping input104which may be connected to the controller110. The carrier mapping-demapping module120may have a transmit output106connected to the frequency-to-time and cyclic prefix addition module112. The carrier mapping-demapping module may have a receive input connected to an output108of the time-to-frequency and cyclic prefix recovery module114. The output108of the time-to-frequency and cyclic prefix recovery module114may be connected to a sense input of the sense module130. The sense module130has an input connected to the transmit output106. In other examples, the sense module130has an input connected to a transmit output of a different channel (not shown) instead of or in addition to the connection to the transmit output106.

An output116of the frequency-to-time and cyclic prefix addition module112may be connected to an input of a DAC118. The output128of the DAC118may be connected via further circuitry (not shown) to one or more antennas of an antenna array (not shown). An input126of the ADC124may be connected via further circuitry (not shown) to one or more antennas of an antenna array (not shown). An output122of the ADC124may be connected to an input of the time-to-frequency and cyclic prefix recovery module114.

In operation, the controller110may configure the operation mode via mode control output134. The operations mode may be one of a communications-transmit mode which may also be referred to as a Down Link (DL) mode, a sense-transmit (ST) mode, a communications-receive mode which may also be referred to as an Up Link (UL) mode, and a sense-receive (SR) mode.

In the communications-transmit mode, binary phase shift key (BPSK), quadrature phase-shift key (QPSK) or quadrature amplitude modulation (QAM) symbols are input to carrier mapping-demapping module120from connection102. These symbols may be referred to in the present disclosure as transmit-OFDM symbols.

In terminology throughout this document, a symbol denotes a complex number (representing for example 1, 2, 4, 6 or 8 data bits) mapped on one of the carriers of an OFDM signal. In the transmit modes of operation, the mapping operation of the carrier mapping-demapping module consists of selecting an input of the inverse Fourier transform for every transmitted symbol. In the receive modes of operation, the de-mapping operation of the carrier mapping-demapping module consists of selecting an output of the Fourier transform for every received symbol.

The controller110may determine a bandwidth part (BWP) of the OFDM spectrum to use for sub-carrier (SC) mapping and provide that information to carrier mapping input104. The transmit-OFDM symbols may be mapped onto in-phase (I) and quadrature (Q) values for every Sub Carrier (SC) resulting in a mapped-transmit-OFDM-symbol which is output on the transmit output106. The mapped-transmit-OFDM-symbol is defined in the frequency domain. The frequency-to-time and cyclic prefix addition module112may implement an inverse discrete Fourier transform (IDFT), typically as an inverse Fast Fourier Transform (IFFT) function which converts the mapped-transmit-OFDM-symbol into the time-domain as a complex (i.e., I and Q) transmit baseband signal. The transmit-baseband-time signal is complemented by a Cyclic Prefix (CP) and digitized by the (IQ)DAC118. The resulting analog transmit-baseband-signal on DAC output128is then sent to an analog front-end (not shown), upconverted into an RF signal by mixing with a Local Oscillator (LO) signal (not shown) and transmitted via an amplifier and antenna (not shown).

In the communications-receive mode, the operation is reversed in sequence with respect to the communications-transmit mode. An RF signal received via an antenna and receive amplifier (not shown) is down converted to an analog receive-baseband-signal provided to the (IQ)ADC124. The ADC124converts the analog baseband signal to a digital complex receive-baseband-signal. The time-to-frequency and cyclic prefix recovery module114may remove the CP guard. The time-to-frequency and cyclic prefix recovery module114may implement a discrete Fourier transform (DFT), typically as a Fast Fourier Transform (FFT) function. The time-to-frequency and cyclic prefix recovery module114converts the time signal into the frequency domain equivalent and outputs the mapped-receive-OFDM-symbol on the output108. The SC are selected (i.e. the mapped-received-OFDM-symbol is de-mapped) by the carrier mapping-demapping module120and processed by a channel equalizer (not shown) and then the resulting receive-OFDM-symbol may be output on the connection102before BPSK, QPSK or QAM decoding (not shown).

In the sense-transmit mode, the transmit-OFDM symbols are sense symbols which may implement a desired radar or sense transmission signal such as a FMCW signal. The controller110may determine a bandwidth part (BWP) of the OFDM spectrum to use for SC mapping and provide that information on mode control output134for the sense symbols. In other respects, the sense-transmit mode is the same as the communications-transmit mode.

In the sense-receive mode an RF signal including a sense signal is received via an antenna and receive amplifier (not shown) is down converted to an analog baseband signal provided to the (IQ)ADC124. The ADC124converts the analog baseband signal to a digital complex baseband time signal. The time-to-frequency and cyclic prefix recovery module114may remove the CP guard. The time-to-frequency and cyclic prefix recovery module114converts the time signal into the frequency domain equivalent and outputs the mapped OFDM symbol on the output108. The mapped-receive-OFDM-symbol may then be input to the sense module130. The sense module130may determine one or more of range, angle-of-arrival, and speed of a sensed object by comparing the mapped-receive-OFDM-symbol with a mapped-transmit-OFDM-symbol including the sense symbol and outputting the range value, angle-of-arrival value and speed value on the sense module output132. The mapped-transmit-OFDM-symbol may be provided by the carrier mapping-demapping module120on the transmit output106on the same channel. In other examples the transmitted sense symbol may be provided to the sense module130from another channel (not shown).

In the present disclosure, the base-station and operating method of a base station may use bandwidth parts for a different purpose to that for which they are normally intended. That is to say the bandwidth parts are used for sensing in a sensing mode rather than for reducing power consumption in the UE. Since the sensing modes of operation may require scanning, the beam direction of a sensing beam may be close to or the same as a communication beam or other sensing beam. Using BWPs may avoid interference between sensing and communication signals. By using bandwidth part(s) in a sensing mode, the base station may use the same antenna array for simultaneous sensing and communication modes of operation or multiple sensing operations in multiple bandwidth parts. The term sensing signal may refer to a transmit or receive signal in a sensing operation mode, i.e. sense-transmit or sense-receive mode. The term communications signal may refer to a transmit or receive signal in a communications operation mode, i.e. communications-transmit or communications-receive mode.

FIG.2shows a detail of an example implementation of the sense module130. A divider module136may have an input connected to an output108of the time-to-frequency and cyclic prefix recovery module114. The divider module136may have an input connected to the transmit output106. The divider module136may have an output138connected to an input of a frequency-to-time conversion module152. The output142of the frequency to time conversion module152may be connected to a time-to-range conversion module146. The time-to-range conversion module146may have a time-to-range conversion module control input144. The time-to-range conversion module146may have time-to-range conversion module output148connected to a range-to-frequency conversion module154. The output of the time-to-frequency conversion module154may be connected to the sense module output132.

A division in the frequency domain of the received signal i.e. mapped-OFDM-receive symbol, denoted R(f) by the spectrum of the transmitted sense signal i.e. mapped-OFDM-transmit-symbol, denoted Xi (f) yields the channel transfer function in the frequency domain, denoted Hi(f). Potentially any waveform of X can be used, but typically a waveform such as a FMCW or other waveform which contains all frequency components is used, while the peak-to-average ratio of the Xi(t) signal is kept as low as possible. The frequency-to-time conversion module152may apply an IFFT or other IDFT transformation on Hi(f), resulting in a channel pulse response Hi(t). The distance to the objects in the field now show as individual pulses in this Hi(t) signal. The pulse amplitudes are a measure of the size of the sensed objects. The pulse response signal Hi(t) is scaled by the time-to-range conversion module146by a range factor R=c*t/2, resulting in range signal Hi(r) on the time-to-range conversion module output148. A series of signals Hi(r) is converted by FFT module154which operates an FFT or other DFT transform over the series of signals Hi(r). This step additionally reveals the object velocity resulting in signal H(r, v).

During operation, in sense-receive mode any equalization which is used in the communications-receive mode is disabled by the controller110, to avoid removing the channel information of interest when in the sense-receive mode. In some examples, the sense symbols may be regularly repeated.

In some examples, since antenna arrays allow for directivity, features may be added to derive angular selectivity. In some examples, in a sense-receive mode, a number of sensing events may be detected by beams having a beam direction covering a number of different angles. The beam angle resulting in the largest received amplitude determines the most likely direction of the object location.

FIG.3shows a method of operation200of a mobile communication base station in a sense mode operation mode including a sense-transmit mode and sense-receive mode according to an embodiment. In step202a sensing signal including a number of sensing symbols is defined. In step204the sensing symbols are mapped on multiple carriers using bandwidth parts and optionally interleaving. Interleaving in this context may include assigning or using segments of the bandwidth part for the sensing symbol leaving other segments of the bandwidth part available for other sensing or communication symbols. In step206, the sensing signal is converted into the time domain. In step208, the sensing signal is converted to an analog sensing signal. In step210the analog sensing signal is up converted and the resulting up-converted sensing signal which may also be referred to as a transmit-signal is transmitted. In step212the signal transmitted according to steps202to210is received. This received sensing signal may be on the same channel or a different channel of a mobile communications base station. The received sensing signal is down converted in step212. In step214the down converted sensing signal which is a received-baseband-signal is converted to a digital signal.

In step216, the digital signal is converted from the time domain to the frequency domain. In step218the range and optionally the velocity and the angle of arrival of an object is determined from the transmitted sensing signal and the sensed sensing signal. The method steps202to206may for example be implemented by the baseband processor140configured in a sense-transmit mode. Method step208may be performed by the digital front end150. Method step210may be performed by an analog front-end. The method steps212,214may be performed respectively by an analog front-end and for example a digital front-end150configured in a sense-receive mode. Steps216and218may for example be implemented by baseband processor140configured in a sense-receive mode. For full-duplex communication, two channels are required, one channel configured in the sense-transmit mode and one configured in the sense-receive mode. For a mobile communication base station, the full-duplex mode is the most commonly required because of the relatively short distances. For longer distances a single channel may be used time multiplexed between sense-transmit and sense-receive mode similarly to the communications modes of operation.

FIG.4shows a mobile communication base station300for a single channel including a baseband processor340, a digital front-end350, and an analog front end360according to an embodiment. The baseband processor340may include a carrier mapping-demapping module320, a controller310, an inverse fast Fourier transform (iFFT) and cyclic prefix addition (CP) module312, a fast Fourier transform (FFT) and cyclic prefix recovery (CP-R) module314, a sense module330. The digital front-end350may include a digital to analog converter (DAC)318, an analog to digital converter (ADC)324and an antenna switch358. The analog front-end360may include an up-down converter342, analog beamformer (ABF)372, transmit and receive amplifiers352(352-1. . .352-N), and antennas354(354-1. . .354-N). The controller310may have a control output334connected to the mapping de-mapping module320and the sense module330. The carrier mapping-demapping module320may have a connection302which may receive or transmit orthogonal frequency division multiplexing (OFDM) symbols. Carrier mapping-demapping module320may have a carrier mapping input304which may be connected to a further control output of the controller310. The carrier mapping-demapping module320may have a transmit output306connected to the iFFT and CP module312. The carrier mapping-demapping module320may have a receive input connected to an output308of the FFT and CP-R module314. The output308of the FFT and CP-R module314may be connected to a sense input of the sense module330. The sense module330may also have a sense module input362which in some examples may be connected to the transmit output306. In other examples, the sense module input362may have an input connected to a transmit output of a different channel (not shown).

An output316of the iFFT and CP module312may be connected to an input of a DAC318. The output328of the DAC318may be connected to a first terminal of antenna switch358. An input326of the ADC324may be connected to a second terminal of antenna switch358. An output322of the ADC324may be connected to an input of FFT and CP-R module314. A third terminal336of the antenna switch358may be connected to a first terminal of the up-down converter342. The up-down converter342may have a local oscillator input338and a second terminal344connected to the analog beamformer372. The analog beam former372includes a number N of beamformer elements346-1to346-N each having a first beamformer element terminal connected to the second terminal344and second beamformer element terminal348-1to348-kconnected to a respective transmit and receive amplifier352-1to352-N. Each transmit and receive amplifier352-1to352-N is connected to an antenna354-1to354-N. A beam control input356which may also be referred to as the beam index input may be connected to the beamformer elements346-1to346-N. The operation of the baseband processor340is similar to baseband processor140in the different operation modes.

Additionally, In the sense-transmit and communications-transmit modes, the controller310controls the antenna switch358via mode control output334to couple the DAC output318to the up-down converter342. In the sense-receive and communications-receive modes, the controller310controls the antenna switch358via mode control output334to couple the ADC input326to the up-down converter342. The beam direction370and shape is determined by the beam index per symbol applied to the beam control input356which controls the beamformer elements346-1to346-N.

FIG.5shows a mobile communication base station380which may be a 5G gNB which includes M-instances of mobile communication base station300. The controller310for each channel may be combined into a single controller. Mobile communication base station380containing K subarrays of each having N=Nx*Ny elements and processing M=K data streams. A subarray may be considered as a group of antenna elements354-1to354-N that transmits or receives the same RF signal, only having its RF phase and/or gain as a free parameter. In operation, the controller310may configure the operation mode of each mobile communication base station channel300-1,300-2,300-M in a communications-transmit mode which may also be referred to as a Down Link (DL) mode, a sense-transmit (ST) mode, a communications-receive mode which may also be referred to as an Up Link (UL) mode, and a sense-receive mode (SR). The mobile communication base station channel300-1,300-2,300-M may have a radiation pattern corresponding to the beam direction and shape of the respective beams370-1,370-2,370-M. The beam direction and shape may be determined by the beam index per symbol applied to the beam control input356. The beam control input356controls the beamformer elements346-1to346-N for each channel300-1,300-2,300-M.

FIG.6Ashows a mobile communication base station400using a digital beamformer470according to an embodiment. The mobile communication base station400has M channels or streams and N antennas. The mobile communication base station400includes N digital front-ends450-1,450-2. . .450-N, and N analog front ends460-1,460-2. . .460-M. The mobile communication base station400includes M carrier mapping de-mapping modules420-1,420-2. . .420-M, a controller410, M sense modules430-1,430-2. . .430-M. The mobile communication base station400includes NiFFT and CP modules412-1,412-2. . .412-N, N FFT and CP-R modules414-1,414-2. . .414-N. Each of the digital front-ends450-1,450-2. . .450-N includes a DAC418-1,418-2. . .418-N, an ADC424-1,424-2. . .424-N and an antenna switch458-1,458-2. . .458-N. The analog front-ends460-1,460-2. . .460-M each include up-own converters442-1,442-2. . .442-N, transmit and receive amplifiers452-1,452-2. . .452-N, and antennas454-1,454-2. . .454-N. The mobile communication base station400includes a digital beamformer470connected between the carrier mapping de-mapping modules420, and the iFFT and CP modules412, and FFT and CP-R modules414.

The controller410may have a control output434connected to the mapping de-mapping modules420and the sense modules430. The carrier mapping-demapping module420may have a connection402which may receive or transmit orthogonal frequency division multiplexing (OFDM) symbols. Carrier mapping-demapping module420may have a carrier mapping input404which may be connected to a further control output of the controller410. The carrier mapping de-mapping modules420may each have a transmit output406connected to the digital beam former470. The carrier mapping de-mapping modules420may each have a receive input connected to a respective receive output408of the digital beamformer470. Note that, for ease of understanding, multiple instances of a feature have the same base reference sign, such as “420-1,420-2, . . .420-N”, may be referred to hereinunder by the base reference sign itself—in this case “420”. Each receive output408of the digital beam former470may be connected to a sense input of the sense module430. The sense modules430may each have an input462which in some examples may be connected to the transmit output406. In other examples, the sense module input462may have an input connected to a transmit output of a different channel (not shown). In some example mobile communications systems including multiple mobile communications base stations400, a first mobile communication base station may have a sense module input462connected to a channel of a second mobile communications base station. In these examples, the first mobile communication base station has a channel configured in a sense-receive mode and the second mobile communication base station has a channel configured in a sense-transmit mode.

An output416of each iFFT and CP module412may be connected to an input of a DAC418. An input of the iFFT and CP module412may be connected to a transmit output478of the digital beamformer470. An input422of each FFT and CP-R module414may be connected to an output of an ADC424. An output of each FFT and CP-R module414may be connected to a receive input480of the digital beamformer470. The output428of the DAC418may be connected to a first terminal of antenna switch458. An input426of the ADC424may be connected to a second terminal of antenna switch458. A third terminal436of the antenna switch458may be connected to a first terminal of the up-down converter442. The up-down converter442may have a local oscillator input438and a second terminal444connected to a respective transmit and receive amplifier452. Each transmit and receive amplifier452may be connected to a respective antenna454. A beamformer controller448has a beam control input464and beam control output456connected to the digital beamformer470.

In operation, the controller410may configure the operation mode of each mobile communication base station channel in a communications-transmit mode which may also be referred to as a Down Link (DL) mode, a sense-transmit (ST) mode, a communications-receive mode which may also be referred to as an Up Link (UL) mode, and a sense-receive mode (SR). The operation of the carrier mapping-demapping module420and sense module430in each channel is similar to carrier mapping-demapping module120and sense module130. The iFFT and CP module412and FFT and CP-R module414operate in a similar way to the iFFT and CP module112and FFT and CP-R module114but as they are after the digital beam former470, they are not assigned to a specific channel.

For mobile communication base station400, the analog front-end460for the transmit and receive modes only performs amplification and up-down conversion. The beam forming is done in the digital domain by digital beamformer470. For a given number of antenna elements N, in principle up to N streams can be mapped. Practically, up to 8 streams are being used. For a given panel size consisting of N antenna elements, this is potentially more than in the ABF case where M is fundamentally limited to K=Ntot/(Nx*Ny).

FIG.6Bshows an example implementation for digital beamformer470. The digital beamformer470includes a first series of M combiner-splitters472(472-1,472-2. . .472-M), a second series of N combiner-splitters476(476-1,476-2. . .476-N), and a series of N groups of multipliers474(474-1,474-2. . .474-N), each multiplier group having M multipliers, each multiplier having a first terminal connected to the beam control output456, a second terminal connected to a respective one of the first series of M combiner-splitters472and a third terminal connected to a respective one of the second series of N combiner-splitters476. Each transmit output406is connected to a respective one of the first series of M combiner-splitters472. The first series of M combiner-splitters472may have an output connected to a respective receive output408(408-1,408-2. . .408-M) of the digital beamformer470. Each transmit output478is connected to a respective one of the second series of N combiner-splitters476. The second series of M combiner-splitters472may have an input connected to a respective receive input480of the digital beamformer470.

The digital amplitude/phase shifters consist of complex multipliers474in the frequency-domain before the iFFT and CP module412for transmit and after the FFT and CP-R module414for receive. A matrix of M*N complex coefficients can arbitrarily map M streams onto N antenna elements454. The amplitude value is denoted Aij and the phase ij where i is the stream value from 1 to M and j is the antenna element varying from 1 to N. The multipliers474may multiply the mapped-transmit-OFDM symbol for the i-th channel or stream by Aij*exp (j*Φij) for each value of j in the communications-transmit or sense transmit mode, or the output from the jth FFT and CP-R module414in the communications-receive or sense-receive mode which may include mapped-receive-OFDM symbols for more than one channel or stream by Aij*exp (j*Φij) for each value of i in the communications-receive or sense-receive mode.

FIG.7Ashows an example of the partitioning of an antenna array500of 16×16 patch antennas502into 4 subarrays504-1,504-2,504-3,504-4of 16×4 elements. Because of the wider aperture in horizontal direction, the beam will have high azimuth resolution and lower elevation resolution. This naturally fits to standard applications where users are widely spread over azimuth angles and ranges but are all near ground elevation level. In typical communication mode, for given symbol and given set of subcarriers, the panel could serve multiple users by 4 individual beams (4 streams multi-user MIMO) or single user by multiple beams (1 stream single-user MIMO).

FIG.7Bshows an example of the partitioning of an antenna array520of 8×8 patch antennas522into 8 subarrays522-1to522-8of 1×8 elements. In typical communication mode, for given symbol and given set of subcarriers, the panel could serve multiple users by 8 individual beams (8 streams multi-user MIMO) or single user by multiple beams (1 stream single-user MIMO).

In 5G-NR, the concept of a Band Width Part (BWP) was introduced for communication. This means that the start frequency of the band and bandwidth of a contiguous set of OFDM carriers is flexible. In a BWP, only a part of the RF frequency spectrum is used. For example, in 5G mobile communication systems, a total bandwidth of 400 MHz may be split into a maximum of 4 bandwidth parts, each covering between 28 MHZ of bandwidth having 20 resource blocks of 12 carriers with 120 kHz spacing and 380 MHz of bandwidth having 264 resource blocks of 12 subcarriers with 120 kHz spacing. UEs only occasionally need the full bandwidth for DL or UL. Significant power saving can be achieved in the UE when using smaller bandwidth whenever that is sufficient, since a smaller bandwidth may allow the UE processor to work at reduced clock speed.

FIG.8Ashows a graph600of an example of dynamic switching between BWPs in a communications-transmit or communications-receive mode of operation. The x-axis shows time and the Y axis shows the OFDM FFT bandwidth. During a first time period602, a first bandwidth part may be active. In a second time period604a different second bandwidth part may be active. In a third time period606the first bandwidth part may be active. In a fourth time period608a third bandwidth part may be used which covers the full bandwidth (FB). In the present disclosure, the base-station and operating method of a base station may use bandwidth parts in the sensing mode for a different purpose to that intended of reducing power consumption in the UE. By using a bandwidth part in a sensing mode, the base station may use the same antenna array for simultaneous sensing and communication modes of operation.

FIG.8Bshows a sensing mode of operation620using BWPs with split frequency bands using interleaved OFDM for different sensing streams according to an embodiment. During a first time period622, a first bandwidth part may be active with the sensing OFDM symbols allocated to sections624of the BWP. In a second time period626a different bandwidth part may be active with the sensing OFDM symbols allocated to sections624of the BWP. In a third time period628the first bandwidth part may be active. In a fourth time period a third bandwidth part630may be used.FIG.8Cshows a sensing mode of operation640using BWPs with split frequency bands with multiple shifted OFDM spectra shown by continuous lines642and dashed lines644.

The methods and mobile base stations described may use Frequency Division Multiple Access for allocating radar sensing bandwidth. Allocating different bandwidth parts BWP may more effectively use the total available bandwidth for radar sensing. In some examples, depending on the required spatial resolution Rr, allocate an appropriate BWP for sensing beams. In some examples an additional BWP may be used for sensing beams to be transmitted and received into/from another direction. Depending on expected or measured interference, assign a BWP for sensing adjacent or overlapping with BWP used for communication. The DL/ST/DL-ST/UL/SR/UL-SR operating mode and corresponding BWP assignment may be updated on any granularity of integer symbol length. Some examples are shown in the table 1 below. For sensing, separate beams are assigned for transmit and receive.

TABLE 1Mode 1Mode 2Mode 3Radar BWPRadar/DL BWPRadar UL BWPBeam 1ST BWP1ST BWP1ST BWP1Beam 2SR BWP1SR BWP1SR BWP1Beam 3ST BWP2DL1 BWP2UL1 BWP2Beam 4SR BWP2DL2 BWP2UL2 BWP2
In some examples the BWP assigned to radar may be split into M interleaved frequency spectra: Depending on required spatial range Ru, the spectrum may be freed-up by only modulating every Mth subcarrier (SC) for a single beam. This effectively increases the SC spacing by a factor of M. The free interleaved spectrum may be used for additional radar scanning beams, operating with a different offset in the SC selection. The DL/ST/DL-ST/UL/SR/UL-SR operating mode and corresponding BWP and IFDM assignment may be updated on any granularity of integer symbol length. Some examples are shown in table 2 below where Nsc is the number of sub carriers used for the OFDM modulation.

TABLE 2Mode 1Mode 2Radar BWP1Radar BWP1interleaved i =interleaved i =1:Nsc/2/DL BWP21:Nsc/2/UL BWP2Beam 1ST SC 1 + (i − 1)*2ST SC 1 + (i − 1)*2Beam 2SR SC 1 + (i − 1)*2SR SC 1 + (i − 1)*2Beam 3ST SC 2 + (i − 1)*2ST SC 2 + (i − 1)*2Beam 4SR SC 2 + (i − 1)*2SR SC 2 + (i − 1)*2Beam 5DL1 BWP2UL1 BWP2Beam 6DL2 BWP2UL2 BWP2Beam 7DL3 BWP2UL3 BWP2Beam 8DL4 BWP2UL4 BWP2

In a joint communication and sensing base station it may be desirable to simultaneously optimize communication throughput and sensing accuracy. Channel capacity from available time, bandwidth and spatial diversity should not be wasted. The formulas determining the unambiguous range Ru, Range resolution Rr, unambiguous Velocity Vuand Velocity resolution Rrin an OFDM-based radar are given in equations 1 to 4 below:

Ru=c×TFFT2=c2×Fs⁢c(1)Ru=c×Tr2(2)Vr=c2×Tf×fc(3)Vu=c4×Ts⁢e⁢p×fc(4)in which c is the velocity of light, TFFTthe FFT length, Fscthe subcarrier spacing and B the occupied bandwidth. Tsepis the time between two sense symbols, Fc the RF frequency and Tfthe total frame length used to measure velocity.

FIGS.9A-9Dshow radar sensing performance in different divisions of the available frequency spectrum for objects located at 5 m, 40 m, and 60 m. In a first case, shown inFIGS.9A,9B, a full bandwidth, which in this example is 1 GHz is used for radar. Graph700shows the frequency in GHz on the x-axis and magnitude in dB on the y axis. Graph710is a 3D plot with range in metres on the x-axis, velocity in meters/second on the y-axis and magnitude on the z-axis. In accordance with equations 1 . . . 4, this results in a range resolution Rr=0.15 m.

In a second case, illustrated byFIGS.9C, and9Donly a 25% BWP corresponding to a bandwidth of 250 MHz is being used as shown in graph720. The remaining 75% of the bandwidth can be used for other purpose. Graph730is a 3D plot with range in metres on the x-axis, velocity in meters/second on the y-axis and magnitude on the z-axis. This shows results a range resolution Rr=0.6 m.

In a third case, illustrated byFIGS.9E, and9Fthe full 1 GHz bandwidth as shown in graph740is 1:4 interleaved. Also in this case, 75% of the remaining bandwidth can be used for other purposes. This 1:4 interleaving increases the effective sub-carrier (SC) spacing by a factor of 4, hence the unambiguous range reduced by a factor of 4 while range resolution is maintained. This is illustrated by graph750in a 3D plot with range in metres on the x-axis, velocity in meters/second on the y-axis and magnitude on the z-axis.

FIG.10shows a mobile communication system800including a central network element810and a base station820which may include a beam forming antenna/image radar sensor. Base station820may be implemented for example using a mobile communication base station380,400. The central network element810may be in communication via a link802with the base station820. In some examples, the central network element810may implement a beamforming algorithm and provide the beam indexes to the base station. In other examples, sensing information retrieved from multiple base stations820may be combined into aggregated sensing data. Combining sensing data may allow false detections to be removed or make use of triangulation for more accurate determination of object location. The mobile communication system800may be a time division duplex (TDD) communications network. The base station820may configure sub-arrays of the antennas to communicate via beams804to various user equipment (UE)806and may be configured to transmit sensing symbol via beams804which reflect off objects such as for example trees812or vehicles808. As illustrated, the base station820is configured as an example with one sub-array having four beams804-1,804-2,804-3,804-4. Beam804-1may be configured in communications-transmit mode or communications-receive mode using an allocated bandwidth part. Beam804-2may be configured in sense-transmit using a different allocated bandwidth part to the communications mode. Beam804-3may be configured in sense-receive mode using a the same bandwidth part as the sense-transmit. Beam804-4may be configured in communications-transmit mode or communications-receive mode using an allocated bandwidth part which is different to the bandwidth part of beams804-1to804-3. The base station820may implement a communication channel to UE806-1via beam804-1and a communication channel to UE806-2via beam804-2. The sense transmit beam804-2direction may vary as may sense receive beam804-2to build a radar image of the surroundings.

The mobile communication system800may include multiple base stations820. In some examples, one of the base stations may have a channel configured in a sense-transmit mode and a different base station may have a channel configured in a sense receive mode. In other examples one or more base stations may have a channel configured in a sense transmit mode and the user equipment806may implement a sense module, for example sense module130. The UE may be provided with the reference of the transmitted sense signal for example via a normal communication channel or some other means, and is configurable in a UE sense receive mode to sense a transmitted sense signal from one or more of the base stations, and determine for example a UE location from the transmitted sense signal.

Embodiments of the mobile communication base station and method may allow one or more antenna subarrays to process sensing symbols while other subarrays are processing communication symbols with relatively low communication BER and/or prevent cluttering in object detection.

Unlike communication mode, mono-static radar sensing normally requires full duplex operation. Sufficient isolation between transmitter and receiver practically implies using separate subarrays for sense transit and sense receive.

Yet, since a subarray using ABF cannot control the direction of radiation for communication and sensing independently, a subpanel in a conventional ABF system would only support the subset DL, ST, UL, SR. By using bandwidth parts, the mobile communication base station described herein may allow a single antenna array consisting of multiple sub arrays to operate in a combined sense and communication mode.

A mobile communication base station for joint communication and sensing and method of operation of a mobile communication base station is described. The mobile communication base station includes a baseband processor configurable to transmit and receive sensing and communication signals via one or channels. Each channel is configurable in one or more of a communications-transmit mode, a communications-receive mode, a sense-transmit mode and a sense-receive mode. For each channel, the baseband processor includes a carrier mapping-demapping module and a sense module. The baseband processor includes a controller coupled to the carrier mapping-demapping module and configured to control the carrier mapping-demapping module to of the one or more channels to: map the plurality of transmit-OFDM-symbols to a bandwidth part of an available OFDM bandwidth in the sense-transmit mode and the communications-transmit mode.

In some example embodiments the set of instructions/method steps described above are implemented as functional and software instructions embodied as a set of executable instructions which are effected on a computer or machine which is programmed with and controlled by said executable instructions. Such instructions are loaded for execution on a processor (such as one or more CPUs). The term processor includes microprocessors, microcontrollers, processor modules or subsystems (including one or more microprocessors or microcontrollers), or other control or computing devices. A processor can refer to a single component or to plural components.

In other examples, the set of instructions/methods illustrated herein and data and instructions associated therewith are stored in respective storage devices, which are implemented as one or more non-transient machine or computer-readable or computer-usable storage media or mediums. Such computer-readable or computer usable storage medium or media is (arc) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The non-transient machine or computer usable media or mediums as defined herein excludes signals, but such media or mediums may be capable of receiving and processing information from signals and/or other transient mediums.

Example embodiments of the material discussed in this specification can be implemented in whole or in part through network, computer, or data based devices and/or services. These may include cloud, internet, intranet, mobile, desktop, processor, look-up table, microcontroller, consumer equipment, infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

In one example, one or more instructions or steps discussed herein are automated. The terms automated or automatically (and like variations thereof) mean controlled operation of an apparatus, system, and/or process using computers and/or mechanical/electrical devices without the necessity of human intervention, observation, effort and/or decision.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness it is also stated that the term “comprising” does not exclude other elements or steps, the term “a” or “an” does not exclude a plurality, a single processor or other unit may fulfil the functions of several means recited in the claims and reference signs in the claims shall not be construed as limiting the scope of the claims.