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refactor lower mac coding part 2
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@marenz2569
marenz2569 committed Jun 7, 2024
1 parent 74c8383 commit ce1afb0
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Showing 2 changed files with 62 additions and 75 deletions.
20 changes: 14 additions & 6 deletions include/l2/lower_mac_coding.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,9 +29,10 @@ struct LowerMacCoding {
*
*/
template <std::size_t Size, typename Type>
static auto descramble(const std::array<Type, Size>& input, std::array<Type, Size>& output,
uint32_t scrambling_code) noexcept -> void {
static auto descramble(const std::array<Type, Size>& input, uint32_t scrambling_code) noexcept
-> std::array<Type, Size> {
static std::map<uint32_t, std::vector<Type>> table_by_scrambling_code;
std::array<Type, Size> output{};

static_assert(Size <= 432);

Expand Down Expand Up @@ -61,19 +62,24 @@ struct LowerMacCoding {
for (std::size_t i = 0; i < Size; i++) {
output[i] = input[i] ^ table[i];
}

return output;
}

/**
* @brief (K,a) block deinterleaver - 8.2.4
*
*/
template <std::size_t Size, typename Type>
static auto deinterleave(const std::array<Type, Size>& data, std::array<Type, Size>& res,
const std::size_t a) noexcept -> void {
static auto deinterleave(const std::array<Type, Size>& data, const std::size_t a) noexcept
-> std::array<Type, Size> {
std::array<Type, Size> res{};
for (std::size_t i = 0; i < Size; i++) {
auto k = 1 + (a * (i + 1)) % ViterbiCodec::K;
res[i] = data[k - 1]; // to interleave: DataOut[i-1] = DataIn[k-1]
}

return res;
}

/**
Expand Down Expand Up @@ -126,8 +132,8 @@ struct LowerMacCoding {
*
*/

static auto reed_muller_3014_decode(const std::array<bool, 30>& input, std::array<bool, 14>& output) noexcept
-> void {
static auto reed_muller_3014_decode(const std::array<bool, 30>& input) noexcept -> std::array<bool, 14> {
std::array<bool, 14> output;
uint8_t q[14][5];

q[0][0] = input[0];
Expand Down Expand Up @@ -327,6 +333,8 @@ struct LowerMacCoding {
// print_vector(res, 14);

// return vector_extract(data, 0, 14);

return output;
}

/**
Expand Down
117 changes: 48 additions & 69 deletions src/l2/lower_mac.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,13 +48,11 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
// bb contains AACH
// ✅ done
std::array<bool, 30> bb_input{};
std::array<bool, 30> bb_desc{};
std::array<bool, 14> bb_rm{};
for (auto i = 0; i < 30; i++) {
bb_input[i] = frame[252 + i];
}
LowerMacCoding::descramble(bb_input, bb_desc, bsc.scrambling_code);
LowerMacCoding::reed_muller_3014_decode(bb_desc, bb_rm);

auto bb_rm = LowerMacCoding::reed_muller_3014_decode(LowerMacCoding::descramble(bb_input, bsc.scrambling_code));
auto _aach =
AccessAssignmentChannel(burst_type, bsc.time, BitVector(std::vector(bb_rm.cbegin(), bb_rm.cend())));

Expand All @@ -64,15 +62,14 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
// see ETSI EN 300 392-2 V3.8.1 (2016-08) Figure 8.6: Error control
// structure for π4DQPSK logical channels (part 2)
std::array<bool, 216> bkn2_input{};
std::array<bool, 216> bkn2_desc{};
std::array<bool, 216> bkn2_dei{};
for (auto i = 0; i < 216; i++) {
bkn2_input[i] = frame[282 + i];
}
LowerMacCoding::descramble(bkn2_input, bkn2_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn2_desc, bkn2_dei, 101);
auto bkn2_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn2_dei));

auto bkn2_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn2_input, bsc.scrambling_code), 101)));

if (LowerMacCoding::check_crc_16_ccitt<140>(bkn2_bits)) {
// SCH/HD or BNCH mapped
functions.emplace_back([this, burst_type, bkn2_bits] {
Expand All @@ -84,28 +81,24 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
// bb contains AACH
// ✅
std::array<bool, 30> bb_input{};
std::array<bool, 30> bb_desc{};
std::array<bool, 14> bb_rm{};
for (auto i = 0; i < 30; i++) {
auto offset = i > 14 ? 266 : 230;
bb_input[i] = frame[offset + i];
}
LowerMacCoding::descramble(bb_input, bb_desc, bsc.scrambling_code);
LowerMacCoding::reed_muller_3014_decode(bb_desc, bb_rm);

auto bb_rm = LowerMacCoding::reed_muller_3014_decode(LowerMacCoding::descramble(bb_input, bsc.scrambling_code));
auto aach = AccessAssignmentChannel(burst_type, bsc.time, BitVector(std::vector(bb_rm.cbegin(), bb_rm.cend())));

// TCH or SCH/F
std::array<bool, 432> bkn1_input{};
std::array<bool, 432> bkn1_desc{};
std::array<bool, 432> bkn1_dei{};
for (auto i = 0; i < 432; i++) {
auto offset = i > 216 ? 282 : 14;
bkn1_input[i] = frame[offset + i];
}
LowerMacCoding::descramble(bkn1_input, bkn1_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn1_desc, bkn1_dei, 103);
auto bkn1_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn1_dei));
};

auto bkn1_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn1_input, bsc.scrambling_code), 103)));

if (aach.downlink_usage == DownlinkUsage::Traffic) {
// TODO: handle TCH
Expand All @@ -127,37 +120,31 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
// bb contains AACH
// ✅ done
std::array<bool, 30> bb_input{};
std::array<bool, 30> bb_desc{};
std::array<bool, 14> bb_rm{};
for (auto i = 0; i < 30; i++) {
auto offset = i > 14 ? 266 : 230;
bb_input[i] = frame[offset + i];
}
LowerMacCoding::descramble(bb_input, bb_desc, bsc.scrambling_code);
LowerMacCoding::reed_muller_3014_decode(bb_desc, bb_rm);

auto bb_rm = LowerMacCoding::reed_muller_3014_decode(LowerMacCoding::descramble(bb_input, bsc.scrambling_code));
auto aach = AccessAssignmentChannel(burst_type, bsc.time, BitVector(std::vector(bb_rm.cbegin(), bb_rm.cend())));

std::array<bool, 216> bkn1_input{};
std::array<bool, 216> bkn1_desc{};
std::array<bool, 216> bkn1_dei{};
for (auto i = 0; i < 216; i++) {
bkn1_input[i] = frame[14 + i];
}
LowerMacCoding::descramble(bkn1_input, bkn1_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn1_desc, bkn1_dei, 101);
auto bkn1_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn1_dei));
};

auto bkn1_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn1_input, bsc.scrambling_code), 101)));

std::array<bool, 216> bkn2_input{};
std::array<bool, 216> bkn2_desc{};
std::array<bool, 216> bkn2_dei{};
for (auto i = 0; i < 216; i++) {
bkn2_input[i] = frame[282 + i];
}
LowerMacCoding::descramble(bkn2_input, bkn2_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn2_desc, bkn2_dei, 101);
auto bkn2_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn2_dei));

auto bkn2_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn2_input, bsc.scrambling_code), 101)));

if (LowerMacCoding::check_crc_16_ccitt<140>(bkn1_bits)) {
if (aach.downlink_usage == DownlinkUsage::Traffic) {
Expand Down Expand Up @@ -203,15 +190,14 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
}
} else if (burst_type == BurstType::ControlUplinkBurst) {
std::array<bool, 168> cb_input{};
std::array<bool, 168> cb_desc{};
std::array<bool, 168> cb_dei{};
for (auto i = 0; i < 168; i++) {
auto offset = i > 84 ? 118 : 4;
cb_input[i] = frame[offset + i];
}
LowerMacCoding::descramble(cb_input, cb_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(cb_desc, cb_dei, 13);
auto cb_bits = LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(cb_dei));
};

auto cb_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(cb_input, bsc.scrambling_code), 13)));

if (LowerMacCoding::check_crc_16_ccitt<108>(cb_bits)) {
functions.emplace_back([this, burst_type, cb_bits] {
Expand All @@ -221,18 +207,16 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
}
} else if (burst_type == BurstType::NormalUplinkBurst) {
std::array<bool, 432> bkn1_input{};
std::array<bool, 432> bkn1_desc{};
std::array<bool, 432> bkn1_dei{};
for (auto i = 0; i < 432; i++) {
auto offset = i > 216 ? 242 : 4;
bkn1_input[i] = frame[offset + i];
}
LowerMacCoding::descramble(bkn1_input, bkn1_desc, bsc.scrambling_code);

// TODO: this can either be a SCH_H or a TCH, depending on the uplink usage marker, but the uplink
// and downlink processing are seperated. We assume a SCH_H here.
LowerMacCoding::deinterleave(bkn1_desc, bkn1_dei, 103);
auto bkn1_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn1_dei));
auto bkn1_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn1_input, bsc.scrambling_code), 103)));

if (LowerMacCoding::check_crc_16_ccitt<284>(bkn1_bits)) {
// fmt::print("NUB Burst crc good\n");
Expand All @@ -245,26 +229,22 @@ auto LowerMac::processChannels(const std::vector<uint8_t>& frame, BurstType burs
}
} else if (burst_type == BurstType::NormalUplinkBurstSplit) {
std::array<bool, 216> bkn1_input{};
std::array<bool, 216> bkn1_desc{};
std::array<bool, 216> bkn1_dei{};
for (auto i = 0; i < 216; i++) {
bkn1_input[i] = frame[4 + i];
}
LowerMacCoding::descramble(bkn1_input, bkn1_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn1_desc, bkn1_dei, 101);
auto bkn1_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn1_dei));

auto bkn1_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn1_input, bsc.scrambling_code), 101)));

std::array<bool, 216> bkn2_input{};
std::array<bool, 216> bkn2_desc{};
std::array<bool, 216> bkn2_dei{};
for (auto i = 0; i < 216; i++) {
bkn2_input[i] = frame[242 + i];
}
LowerMacCoding::descramble(bkn2_input, bkn2_desc, bsc.scrambling_code);
LowerMacCoding::deinterleave(bkn2_desc, bkn2_dei, 101);
auto bkn2_bits =
LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(bkn2_dei));
};

auto bkn2_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(LowerMacCoding::deinterleave(
LowerMacCoding::descramble(bkn2_input, bsc.scrambling_code), 101)));

// STCH + TCH
// STCH + STCH
Expand Down Expand Up @@ -311,14 +291,13 @@ auto LowerMac::process(const std::vector<uint8_t>& frame, BurstType burst_type)
// sb contains BSCH
// ✅ done
std::array<bool, 120> sb_input{};
std::array<bool, 120> sb_desc{};
std::array<bool, 120> sb_dei{};
for (auto i = 0; i < 30; i++) {
sb_input[i] = frame[94 + i];
}
LowerMacCoding::descramble(sb_input, sb_desc, 0x0003);
LowerMacCoding::deinterleave(sb_desc, sb_dei, 11);
auto sb_bits = LowerMacCoding::viter_bi_decode_1614(viter_bi_codec_1614_, LowerMacCoding::depuncture23(sb_dei));
};

auto sb_bits = LowerMacCoding::viter_bi_decode_1614(
viter_bi_codec_1614_, LowerMacCoding::depuncture23(
LowerMacCoding::deinterleave(LowerMacCoding::descramble(sb_input, 0x0003), 11)));

if (LowerMacCoding::check_crc_16_ccitt<76>(sb_bits)) {
current_sync = BroadcastSynchronizationChannel(
Expand Down

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