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authorVadim Yanitskiy <axilirator@gmail.com>2019-07-02 13:31:56 +0700
committerVadim Yanitskiy <axilirator@gmail.com>2019-07-02 13:46:10 +0700
commitdce8a24a2c82f6e36c44bca318f741848caa5ad4 (patch)
treef8d41a0fd0ceddddecd43c8af82b26ae3a89f905
parentaf60c1bb10ad19be41e5eb54d067937f12c64470 (diff)
trx_toolkit/data_msg.py: introduce header coding version 0x01
The new version adds the following fields to the TRX2L1 message, keeping the L12TRX message unchanged: +------+-----+-----+-----+--------------------+ | RSSI | ToA | MTS | C/I | soft-bits (254..0) | +------+-----+-----+-----+--------------------+ - MTS (1 octet) - Modulation and Training Sequence info, and - C/I (2 octets) - Carrier-to-Interference ratio (big endian). == Coding of MTS: Modulation and Training Sequence info 3GPP TS 45.002 version 15.1.0 defines several modulation types, and a few sets of training sequences for each type. The most common are GMSK and 8-PSK (which is used in EDGE). +-----------------+---------------------------------------+ | 7 6 5 4 3 2 1 0 | bit numbers (value range) | +-----------------+---------------------------------------+ | . . . . . X X X | Training Sequence Code (0..7) | +-----------------+---------------------------------------+ | . X X X X . . . | Modulation, TS set number (see below) | +-----------------+---------------------------------------+ | X . . . . . . . | IDLE / nope frame indication (0 or 1) | +-----------------+---------------------------------------+ The bit number 7 (MSB) is set to high when either nothing has been detected, or during IDLE frames, so we can deliver noise levels, and avoid clock gaps on the L1 side. Other bits are ignored, and should be set to low (0) in this case. == Coding of modulation and TS set number GMSK has 4 sets of training sequences (see tables 5.2.3a-d), while 8-PSK (see tables 5.2.3f-g) and the others have 2 sets. Access and Synchronization bursts also have several synch. sequences. +-----------------+---------------------------------------+ | 7 6 5 4 3 2 1 0 | bit numbers (value range) | +-----------------+---------------------------------------+ | . 0 0 X X . . . | GMSK, 4 TS sets (0..3) | +-----------------+---------------------------------------+ | . 0 1 0 X . . . | 8-PSK, 2 TS sets (0..1) | +-----------------+---------------------------------------+ | . 0 1 1 X . . . | AQPSK, 2 TS sets (0..1) | +-----------------+---------------------------------------+ | . 1 0 0 X . . . | 16QAM, 2 TS sets (0..1) | +-----------------+---------------------------------------+ | . 1 0 1 X . . . | 32QAM, 2 TS sets (0..1) | +-----------------+---------------------------------------+ | . 1 1 1 X . . . | RESERVED (0) | +-----------------+---------------------------------------+ == C/I: Carrier-to-Interference ratio The C/I value is computed from the training sequence of each burst, where we can compare the "ideal" training sequence with the actual training sequence, and then express that difference in centiBels. Change-Id: Ie810c5a482d1c908994e8cdd32a2ea641ae7cedd Related: OS#4006, OS#1855
-rw-r--r--src/target/trx_toolkit/data_msg.py395
1 files changed, 362 insertions, 33 deletions
diff --git a/src/target/trx_toolkit/data_msg.py b/src/target/trx_toolkit/data_msg.py
index 5bd04cac..a2996abe 100644
--- a/src/target/trx_toolkit/data_msg.py
+++ b/src/target/trx_toolkit/data_msg.py
@@ -25,8 +25,37 @@
import random
import struct
+from enum import Enum
from gsm_shared import *
+class Modulation(Enum):
+ """ Modulation types defined in 3GPP TS 45.002 """
+ ModGMSK = (0b0000, 148)
+ Mod8PSK = (0b0100, 444)
+ ModAQPSK = (0b0110, 296)
+ Mod16QAM = (0b1000, 592)
+ Mod32QAM = (0b1010, 740)
+
+ def __init__(self, coding, bl):
+ # Coding in TRXD header
+ self.coding = coding
+ # Burst length
+ self.bl = bl
+
+ @classmethod
+ def pick(self, coding):
+ for mod in list(self):
+ if mod.coding == coding:
+ return mod
+ return None
+
+ @classmethod
+ def pick_by_bl(self, bl):
+ for mod in list(self):
+ if mod.bl == bl:
+ return mod
+ return None
+
class DATAMSG:
""" TRXD (DATA) message codec (common part).
@@ -92,7 +121,7 @@ class DATAMSG:
# NOTE: up to 16 versions can be encoded
CHDR_VERSION_MAX = 0b1111
- known_versions = [0x00]
+ known_versions = [0x00, 0x01]
# Common constructor
def __init__(self, fn = None, tn = None, burst = None, ver = 0):
@@ -101,6 +130,12 @@ class DATAMSG:
self.fn = fn
self.tn = tn
+ # The common header length
+ @property
+ def CHDR_LEN(self):
+ # (VER + TN) + FN
+ return 1 + 4
+
# Generates message specific header
def gen_hdr(self):
raise NotImplementedError
@@ -197,12 +232,6 @@ class DATAMSG:
if not self.ver in self.known_versions:
return False
- if self.burst is None:
- return False
-
- if len(self.burst) not in (GSM_BURST_LEN, EDGE_BURST_LEN):
- return False
-
if self.fn is None:
return False
@@ -237,7 +266,8 @@ class DATAMSG:
buf += hdr
# Generate burst
- buf += self.gen_burst()
+ if self.burst is not None:
+ buf += self.gen_burst()
# This is a rudiment from (legacy) OpenBTS transceiver,
# some L1 implementations still expect two dummy bytes.
@@ -248,11 +278,8 @@ class DATAMSG:
# Parses a TRX DATA message
def parse_msg(self, msg):
- # Calculate message length
- length = len(msg)
-
- # Check length
- if length < (self.HDR_LEN + GSM_BURST_LEN):
+ # Make sure we have at least header
+ if len(msg) < self.HDR_LEN:
raise ValueError("Message is to short")
# Parse version and TDMA TN
@@ -267,7 +294,10 @@ class DATAMSG:
# Copy burst, skipping header
msg_burst = msg[self.HDR_LEN:]
- self.parse_burst(msg_burst)
+ if len(msg_burst) > 0:
+ self.parse_burst(msg_burst)
+ else:
+ self.burst = None
class DATAMSG_L12TRX(DATAMSG):
""" L12TRX (L1 -> TRX) message codec.
@@ -276,6 +306,8 @@ class DATAMSG_L12TRX(DATAMSG):
or an Uplink burst on the MS side, and has the following
message specific fixed-size header preceding the burst bits:
+ == Versions 0x00, 0x01
+
+-----+--------------------+
| PWR | hard-bits (1 or 0) |
+-----+--------------------+
@@ -290,13 +322,26 @@ class DATAMSG_L12TRX(DATAMSG):
"""
# Constants
- HDR_LEN = 6
PWR_MIN = 0x00
PWR_MAX = 0xff
# Specific message fields
pwr = None
+ # Calculates header length depending on its version
+ @property
+ def HDR_LEN(self):
+ # Common header length
+ length = self.CHDR_LEN
+
+ # Message specific header length
+ if self.ver in (0x00, 0x01):
+ length += 1 # PWR
+ else:
+ raise IndexError("Unhandled version %u" % self.ver)
+
+ return length
+
# Validates the message fields
def validate(self):
# Validate common fields
@@ -309,6 +354,14 @@ class DATAMSG_L12TRX(DATAMSG):
if self.pwr < self.PWR_MIN or self.pwr > self.PWR_MAX:
return False
+ # FIXME: properly handle IDLE / NOPE indications
+ if self.burst is None:
+ return False
+
+ # FIXME: properly handle IDLE / NOPE indications
+ if len(self.burst) not in (GSM_BURST_LEN, EDGE_BURST_LEN):
+ return False
+
return True
# Generates a random power level
@@ -394,16 +447,78 @@ class DATAMSG_TRX2L1(DATAMSG):
or a Downlink burst on the MS side, and has the following
message specific fixed-size header preceding the burst bits:
+ == Version 0x00
+
+------+-----+--------------------+
| RSSI | ToA | soft-bits (254..0) |
+------+-----+--------------------+
+ == Version 0x01
+
+ +------+-----+-----+-----+--------------------+
+ | RSSI | ToA | MTS | C/I | soft-bits (254..0) |
+ +------+-----+-----+-----+--------------------+
+
where:
- RSSI (1 octet) - Received Signal Strength Indication
encoded without the negative sign.
- ToA (2 octets) - Timing of Arrival in units of 1/256
of symbol (big endian).
+ - MTS (1 octet) - Modulation and Training Sequence info.
+ - C/I (2 octets) - Carrier-to-Interference ratio (big endian).
+
+ == Coding of MTS: Modulation and Training Sequence info
+
+ 3GPP TS 45.002 version 15.1.0 defines several modulation types,
+ and a few sets of training sequences for each type. The most
+ common are GMSK and 8-PSK (which is used in EDGE).
+
+ +-----------------+---------------------------------------+
+ | 7 6 5 4 3 2 1 0 | bit numbers (value range) |
+ +-----------------+---------------------------------------+
+ | . . . . . X X X | Training Sequence Code (0..7) |
+ +-----------------+---------------------------------------+
+ | . X X X X . . . | Modulation, TS set number (see below) |
+ +-----------------+---------------------------------------+
+ | X . . . . . . . | IDLE / nope frame indication (0 or 1) |
+ +-----------------+---------------------------------------+
+
+ The bit number 7 (MSB) is set to high when either nothing has been
+ detected, or during IDLE frames, so we can deliver noise levels,
+ and avoid clock gaps on the L1 side. Other bits are ignored,
+ and should be set to low (0) in this case. L16 shall be set to 0x00.
+
+ == Coding of modulation and TS set number
+
+ GMSK has 4 sets of training sequences (see tables 5.2.3a-d),
+ while 8-PSK (see tables 5.2.3f-g) and the others have 2 sets.
+ Access and Synchronization bursts also have several synch.
+ sequences.
+
+ +-----------------+---------------------------------------+
+ | 7 6 5 4 3 2 1 0 | bit numbers (value range) |
+ +-----------------+---------------------------------------+
+ | . 0 0 X X . . . | GMSK, 4 TS sets (0..3) |
+ +-----------------+---------------------------------------+
+ | . 0 1 0 X . . . | 8-PSK, 2 TS sets (0..1) |
+ +-----------------+---------------------------------------+
+ | . 0 1 1 X . . . | AQPSK, 2 TS sets (0..1) |
+ +-----------------+---------------------------------------+
+ | . 1 0 0 X . . . | 16QAM, 2 TS sets (0..1) |
+ +-----------------+---------------------------------------+
+ | . 1 0 1 X . . . | 32QAM, 2 TS sets (0..1) |
+ +-----------------+---------------------------------------+
+ | . 1 1 1 X . . . | RESERVED (0) |
+ +-----------------+---------------------------------------+
+
+ == C/I: Carrier-to-Interference ratio
+
+ The C/I value can be computed from the training sequence of each
+ burst, where we can compare the "ideal" training sequence with
+ the actual training sequence and then express that in centiBels.
+
+ == Coding of the burst bits
Unlike to be transmitted bursts, the received bursts are designated
using the soft-bits notation, so the receiver can indicate its
@@ -416,9 +531,6 @@ class DATAMSG_TRX2L1(DATAMSG):
"""
- # Constants
- HDR_LEN = 8
-
# rxlev2dbm(0..63) gives us [-110..-47], plus -10 dbm for noise
RSSI_MIN = -120
RSSI_MAX = -47
@@ -427,11 +539,81 @@ class DATAMSG_TRX2L1(DATAMSG):
TOA256_MIN = -32768
TOA256_MAX = 32767
+ # TSC (Training Sequence Code) range
+ TSC_RANGE = range(0, 8)
+
+ # C/I range (in centiBels)
+ CI_MIN = -1280
+ CI_MAX = 1280
+
+ # IDLE frame / nope detection indicator
+ NOPE_IND = (1 << 7)
+
# Specific message fields
rssi = None
toa256 = None
- # Validates the message fields
+ # Version 0x01 specific (default values)
+ mod_type = Modulation.ModGMSK
+ nope_ind = False
+
+ tsc_set = None
+ tsc = None
+ ci = None
+
+ # Calculates header length depending on its version
+ @property
+ def HDR_LEN(self):
+ # Common header length
+ length = self.CHDR_LEN
+
+ # Message specific header length
+ if self.ver == 0x00:
+ # RSSI + ToA
+ length += 1 + 2
+ elif self.ver == 0x01:
+ # RSSI + ToA + TS + C/I
+ length += 1 + 2 + 1 + 2
+ else:
+ raise IndexError("Unhandled version %u" % self.ver)
+
+ return length
+
+ def _validate_burst_v0(self):
+ # Burst is mandatory
+ if self.burst is None:
+ return False
+
+ # ... and can be either of GSM (GMSK) or EDGE (8-PSK)
+ if len(self.burst) not in (GSM_BURST_LEN, EDGE_BURST_LEN):
+ return False
+
+ return True
+
+ def _validate_burst_v1(self):
+ # Burst is omitted in case of an IDLE / NOPE indication
+ if self.nope_ind and self.burst is None:
+ return True
+ if self.nope_ind and self.burst is not None:
+ return False
+
+ if self.burst is None:
+ return False
+
+ # Burst length depends on modulation type
+ if len(self.burst) != self.mod_type.bl:
+ return False
+
+ return True
+
+ # Validates the burst
+ def validate_burst(self):
+ if self.ver == 0x00:
+ return self._validate_burst_v0()
+ elif self.ver >= 0x01:
+ return self._validate_burst_v1()
+
+ # Validates the message header fields
def validate(self):
# Validate common fields
if not DATAMSG.validate(self):
@@ -449,6 +631,35 @@ class DATAMSG_TRX2L1(DATAMSG):
if self.toa256 < self.TOA256_MIN or self.toa256 > self.TOA256_MAX:
return False
+ if self.ver >= 0x01:
+ if type(self.mod_type) is not Modulation:
+ return False
+
+ if self.tsc_set is None:
+ return False
+
+ if self.mod_type is Modulation.ModGMSK:
+ if self.tsc_set not in range(0, 4):
+ return False
+ else:
+ if self.tsc_set not in range(0, 2):
+ return False
+
+ if self.tsc is None:
+ return False
+
+ if self.tsc not in self.TSC_RANGE:
+ return False
+
+ if self.ci is None:
+ return False
+
+ if self.ci < self.CI_MIN or self.ci > self.CI_MAX:
+ return False
+
+ if not self.validate_burst():
+ return False
+
return True
# Generates a random RSSI value
@@ -477,6 +688,17 @@ class DATAMSG_TRX2L1(DATAMSG):
self.rssi = self.rand_rssi()
self.toa256 = self.rand_toa256()
+ if self.ver >= 0x01:
+ self.mod_type = random.choice(list(Modulation))
+ if self.mod_type is Modulation.ModGMSK:
+ self.tsc_set = random.randint(0, 3)
+ else:
+ self.tsc_set = random.randint(0, 1)
+ self.tsc = random.choice(self.TSC_RANGE)
+
+ # C/I: Carrier-to-Interference ratio
+ self.ci = random.randint(self.CI_MIN, self.CI_MAX)
+
# Generates human-readable header description
def desc_hdr(self):
# Describe the common part
@@ -488,9 +710,61 @@ class DATAMSG_TRX2L1(DATAMSG):
if self.toa256 is not None:
result += ("toa256=%d " % self.toa256)
+ if self.ver >= 0x01:
+ if not self.nope_ind:
+ if self.mod_type is not None:
+ result += ("%s " % self.mod_type)
+ if self.tsc_set is not None:
+ result += ("set=%u " % self.tsc_set)
+ if self.tsc is not None:
+ result += ("tsc=%u " % self.tsc)
+ if self.ci is not None:
+ result += ("C/I=%d cB " % self.ci)
+ else:
+ result += "(IDLE / NOPE IND) "
+
# Strip useless whitespace and return
return result.strip()
+ # Encodes Modulation and Training Sequence info
+ def gen_mts(self):
+ # IDLE / nope indication has no MTS info
+ if self.nope_ind:
+ return self.NOPE_IND
+
+ # TSC: . . . . . X X X
+ mts = self.tsc & 0b111
+
+ # MTS: . X X X X . . .
+ mts |= self.mod_type.coding << 3
+ mts |= self.tsc_set << 3
+
+ return mts
+
+ # Parses Modulation and Training Sequence info
+ def parse_mts(self, mts):
+ # IDLE / nope indication has no MTS info
+ self.nope_ind = (mts & self.NOPE_IND) > 0
+ if self.nope_ind:
+ self.mod_type = None
+ self.tsc_set = None
+ self.tsc = None
+ return
+
+ # TSC: . . . . . X X X
+ self.tsc = mts & 0b111
+
+ # MTS: . X X X X . . .
+ mts = (mts >> 3) & 0b1111
+ if (mts & 0b1100) > 0:
+ # Mask: . . . . M M M S
+ self.mod_type = Modulation.pick(mts & 0b1110)
+ self.tsc_set = mts & 0b1
+ else:
+ # GMSK: . . . . 0 0 S S
+ self.mod_type = Modulation.ModGMSK
+ self.tsc_set = mts & 0b11
+
# Generates message specific header part
def gen_hdr(self):
# Allocate an empty byte-array
@@ -503,6 +777,17 @@ class DATAMSG_TRX2L1(DATAMSG):
# Big endian, 2 bytes (int32_t)
buf += struct.pack(">h", self.toa256)
+ if self.ver >= 0x01:
+ # Modulation and Training Sequence info
+ mts = self.gen_mts()
+ buf.append(mts)
+
+ # C/I: Carrier-to-Interference ratio (in centiBels)
+ if not self.nope_ind:
+ buf += struct.pack(">h", self.ci)
+ else:
+ buf += bytearray(2)
+
return buf
# Parses message specific header part
@@ -513,6 +798,16 @@ class DATAMSG_TRX2L1(DATAMSG):
# Parse ToA (Time of Arrival)
self.toa256 = struct.unpack(">h", hdr[6:8])[0]
+ if self.ver >= 0x01:
+ # Modulation and Training Sequence info
+ self.parse_mts(hdr[8])
+
+ # C/I: Carrier-to-Interference ratio (in centiBels)
+ if not self.nope_ind:
+ self.ci = struct.unpack(">h", hdr[9:11])[0]
+ else:
+ self.ci = None
+
# Generates message specific burst
def gen_burst(self):
# Convert soft-bits to unsigned soft-bits
@@ -521,26 +816,38 @@ class DATAMSG_TRX2L1(DATAMSG):
# Encode to bytes
return bytearray(burst_usbits)
+ # Parses message specific burst for header version 0
+ def _parse_burst_v0(self, burst):
+ bl = len(burst)
+
+ # We need to guess modulation by the length of burst
+ self.mod_type = Modulation.pick_by_bl(bl)
+ if self.mod_type is None:
+ # Some old transceivers append two dummy bytes
+ self.mod_type = Modulation.pick_by_bl(bl - 2)
+
+ if self.mod_type is None:
+ raise ValueError("Odd burst length")
+
+ return burst[:self.mod_type.bl]
+
# Parses message specific burst
def parse_burst(self, burst):
- length = len(burst)
+ burst = list(burst)
- # Distinguish between GSM and EDGE
- if length >= EDGE_BURST_LEN:
- burst_usbits = list(burst[:EDGE_BURST_LEN])
- else:
- burst_usbits = list(burst[:GSM_BURST_LEN])
+ if self.ver == 0x00:
+ burst = self._parse_burst_v0(burst)
# Convert unsigned soft-bits to soft-bits
- burst_sbits = self.usbit2sbit(burst_usbits)
-
- # Save
- self.burst = burst_sbits
+ self.burst = self.usbit2sbit(burst)
# Generate a random message specific burst
- def rand_burst(self, length = GSM_BURST_LEN):
+ def rand_burst(self, length = None):
self.burst = []
+ if length is None:
+ length = self.mod_type.bl
+
for i in range(length):
sbit = random.randint(-127, 127)
self.burst.append(sbit)
@@ -697,12 +1004,20 @@ if __name__ == '__main__':
assert(msg_l12trx_dec.tn == msg_l12trx.tn)
assert(msg_trx2l1_dec.fn == msg_trx2l1.fn)
+ # Match version specific fields
+ if msg_trx2l1.ver >= 0x01:
+ assert(msg_trx2l1_dec.nope_ind == msg_trx2l1.nope_ind)
+ assert(msg_trx2l1_dec.mod_type == msg_trx2l1.mod_type)
+ assert(msg_trx2l1_dec.tsc_set == msg_trx2l1.tsc_set)
+ assert(msg_trx2l1_dec.tsc == msg_trx2l1.tsc)
+ assert(msg_trx2l1_dec.ci == msg_trx2l1.ci)
+
+ log.info("Check header version %u coding: OK" % ver)
+
# Compare bursts
assert(msg_l12trx_dec.burst == msg_l12trx.burst)
assert(msg_trx2l1_dec.burst == msg_trx2l1.burst)
- log.info("Check header version %u coding: OK" % ver)
-
msg_trx2l1_gen = msg_l12trx.gen_trx2l1()
msg_l12trx_gen = msg_trx2l1.gen_l12trx()
@@ -717,4 +1032,18 @@ if __name__ == '__main__':
assert(msg_trx2l1_gen.tn == msg_l12trx.tn)
assert(msg_l12trx_gen.fn == msg_trx2l1.fn)
- log.info("Verify direct transformation: OK")
+ log.info("Verify version %u direct transformation: OK" % ver)
+
+ # Verify NOPE indication coding
+ if msg_trx2l1.ver >= 0x01:
+ msg_trx2l1 = DATAMSG_TRX2L1(ver = ver)
+ msg_trx2l1.nope_ind = True
+ msg_trx2l1.rand_hdr()
+
+ msg_trx2l1_dec = DATAMSG_TRX2L1()
+ msg_trx2l1_dec.parse_msg(msg_trx2l1.gen_msg())
+
+ assert(msg_trx2l1.nope_ind == msg_trx2l1_dec.nope_ind)
+ assert(msg_trx2l1.burst == msg_trx2l1_dec.burst)
+
+ log.info("Verify version %u NOPE indication coding: OK" % ver)