HRP-UWB

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General

Bands of operation:
The sub-gigahertz band: consists of a single channel from 249.6 MHz to 749.6 MHz;

The low band: consists of four channels from 3.1 GHz to 4.8 GHz;
The high band: consists of 11 channels from 6.0 GHz to 10.6 GHz;

Preamble:

        The combination of a channel and a preamble code is termed a complex channel.
        A compliant device shall implement support for at least one of the channels (0, 3, or 9).
        each device shall support the two unique length 31 preamble codes for the implemented channels.

Modulation:

The combined BPM-BPSK(Burst Position Modulation) is used to modulate the symbols, with each symbol being composed of an active burst of UWB pulses.

Work flow:

HRP UWB PPDU format

        The mandatory SHR base rates are 1.01 Msymbol/s and 0.25 Msymbol/s as indicated in Table 16-5
             The PHR is sent at 850 kb/s for all data rates greater than or equal to 850 kb/s and at 110 kb/s for the data rate of 110 kb/s. The PSDU is sent at the desired information data rate as defined in Table 16-4.
   STS packet structure
Symbol structure
In the BPM-BPSK modulation scheme, each symbol is capable of carrying two bits of information
The structure and timing of a symbol is illustrated in Figure 16-4.

Each symbol shall consist of an integer number of possible chip positions, Nc,each with duration Tc.
The overall symbol period denoted by Tdsym, Tdsym = NcTc.
A burst is formed by grouping Ncpb consecutive chips and has duration Tburst = NcpbxTc.
The total number of burst durations per symbol, Nburst, is given by Nburst = Tdsym /Tburst.
only the first Nhop= Nburst/4 possible burst positions are candidate hopping burst positions within each BPM interval.

The peak PRF states the highest frequency in megahertz at which a compliant transmitter shall emit pulses.

The peak PRF is also used to derive the chip duration Tc by the formula Tc = 1/(peakPRF).
The symbol rate parameter is the inverse of the PSDU symbol period 1/Tdsym.

bit rate parameter is the user information rate considering FEC:

        Bit Rate = 2 × (Overall FEC Rate)/Tdsym
        The mean PRF parameter is the average PRF during the PSDU portion of a PHY frame
        Mean PRF = Ncpb/Tdsym.

SHR field

Four mandatory preambles are defined: a default preamble, a short preamble, a medium preamble, and a long preamble.

The HRP UWB PHY supports two lengths of preamble code: a length 31 code and an optional length 127 code.

The HRP-ERDEV shall support the length 91 codes specified in Table 16-9.

using the ternary code indexed by i, the SYNC field shall consist of Nsync repetitions of the symbol Si, where Si is the code Ci spread by the delta function $\delta_L$ of length L as shown in Table 16-5.

The length of the SYNC field scales with the number of PSR, that is the Nsync repetitions of Si. In HPRF mode, the HRP-ERDEV shall support transmission and reception with PSR values of 32 and 64,with optional PSR values being 16, 24, 48, 96, 128, and 256.

SFD field

The short SFD shall be [0 +1 0 –1 +1 0 0 –1] spread by the preamble symbol Si, where the leftmost bit shall be transmitted first in time.

The long SFD shall be obtained by spreading the sequence [0 +1 0 –1 +1 0 0 –1 0 +1 0 –1 +1 0 0 –1 –1 0 0 +1 0 –1 0 +1 0 +1 0 0 0 –1 0 –1 0 –1 0 0 +1 0 –1 –1 0 –1 +1 0 0 0 0 +1 +1 0 0 –1 –1 –1 +1 –1 +1 +1 0 0 0 0 +1 +1] by the preamble symbol Si.

In the BPRF mode, the HRP-ERDEV shall support the length 8 SFD specified in Table 16-11

In the HPRF mode, the HRP-ERDEV shall support the length 4, 8, and 16 SFD,the length 32 SFD is optional.

PHR field

PHR field for HRP-ERDEV in BPRF mode

PHR field for HRP-ERDEV in HPRF mode

PHY Payload field

Scrambled timestamp sequence (STS) field

The STS consists of a sequence of pseudo-randomized pulses generated, as specified below, using a DRBG based on AES-128 in counter mode.These pulse sequences are arranged in (one to four) blocks of active segments encapsulated by silent intervals, called “gaps”. The duration of these gaps shall be 512 chips.

Figure 16-10 shows the extent of the STS when consisting of one or two segments. Table 16-10 specifies the numbers of segments and the segment lengths that shall be supported.

Forming the STS

Each iteration of the DRBG specified in 16.2.9.2 produces a 128-bit pseudo-random number. This is taken and transmitted most significant bit first, where each bit of value zero produces a positive polarity pulse and each bit of value one produces a negative polarity pulse. These are spread as described in 16.2.6.2 by the delta function $\delta_L$ of length L = 8 in the BPRF mode, and of length L = 4 in the HPRF mode.

Modulation

Modulation mathematical framework

Spread

The polynomial for the scrambler generator shall be $g(D)= 1+ D^{14} + D^{15}$

$S_n = S_{n-14} \bigoplus S_{n-15}$

The initial state of the LFSR shall be determined from the preamble code by first removing all the zeros in the ternary code and then replacing all the negative ones with a zero. The first 15 bits of the resulting binary state shall be loaded into the LFSR.

HRP-ERDEV modulation in HPRF mode

Modulation at 249.6 MHz PRF

For this 249.6 MHz PRF data modulation, with the mandatory Reed-Solomon coding the data modulation rate is approximately 27 Mb/s. When employing the optional HRP-ERDEV convolutional encoder (where Reed-Solomon coding is not applied) the resultant data modulation rate is approximately 31 Mb/s.

Modulation at 124.8 MHz PRF

For this 124.8 MHz PRF data modulation, with the mandatory Reed-Solomon coding the data modulation rate is approximately 6.8 Mb/s. When employing the optional HRP-ERDEV convolutional encoder (where Reed-Solomon coding is not applied) the resultant data modulation rate is approximately 7.8 Mb/s.

Reference code

spreadingSeq = allPNSamples(offset+1+(currSym-1)*numChips(PHRorPSDU): offset+currSym*numChips(PHRorPSDU), 1);

len = 4*249.6/cfg.MeanPRFNum;
symbolMap = hrpHPRFSymbolMap(cfg.MeanPRFNum, cfg.ConstraintLength);

thisMapping = symbolMap(1+bit2int([systematicBit parityBit]', 2, false), 1:numBits);
scrambled = (1-2*thisMapping) .* (1-2*spreadingSeq');
% add guardbands:
scrambled = [reshape(scrambled, len, []);  zeros(len, numBits/len)];
scrambled = scrambled(:);

RF requirements

Operating frequency bands

Baseband impulse response

The transmitted pulse shape p(t) shall be constrained by the shape of its cross-correlation function with a standard reference pulse, r(t).

$\phi( \tau ) = \frac{1}{\sqrt{E_r E_p}}Re\int{r(t)p^*(t+\tau)dt}$

E r and Ep are the energies of r(t) and p(t), respectively, p* denotes the complex conjugate of p, and, Re indicates that the real part is used. The reference r(t) pulse used in the calculation of $\phi( \tau )$ is a root raised cosine pulse with a roll-off factor of $\beta$ = 0.50.

$r(t) = \frac{4 \beta }{\pi \sqrt{T_p} } \frac{cos[(1+\beta) \pi /T_p]}{ 4\beta(t/T_p)^2}$

the function | $\phi( \tau )$ | is greater than 0.8. In addition, the second constraint on the value of sidelobes may be stated mathematically as | $\phi( \tau )$ | <= 0.3 for all $\tau_i$ .

For a device electing to use a pulse with precursor, it is recommended that the transmitted pulse follows the mathematical formula of the reference root raised cosine pulse r(t) with a roll-off factor of $\beta$ = 0.45, over at least ±3 chip periods

If the transmitted pulse follows the minimum precursor pulse recommendation, the transmitted pulse shape p(t) should be constrained by the time domain mask of Figure 16-24

Transmit PSD mask

The transmitted spectrum shall be less than –10 dB relative to the maximum spectral density of the signal for 0.65/Tp < |f – fc| < 0.8/Tp and –18 dB for |f – fc| > 0.8/Tp. For example, the transmit spectrum mask for channel 4 is shown in Figure 16-25. The measurements shall be made using a 1 MHz resolution bandwidth and a 1 kHz video bandwidth.