summaryrefslogtreecommitdiffstats
path: root/src/target/trx_toolkit/gsm_shared.py
blob: c8c6b8fe83e15e799640dc607b4ddd33402034cd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
#!/usr/bin/env python
# -*- coding: utf-8 -*-

# TRX Toolkit
# Common GSM constants and helpers
#
# (C) 2018-2020 by Vadim Yanitskiy <axilirator@gmail.com>
# Contributions by sysmocom - s.f.m.c. GmbH
#
# All Rights Reserved
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

from enum import Enum

# TDMA definitions
GSM_SUPERFRAME = 26 * 51
GSM_HYPERFRAME = 2048 * GSM_SUPERFRAME

# Burst length
GSM_BURST_LEN = 148
EDGE_BURST_LEN = GSM_BURST_LEN * 3

class BurstType(Enum):
	""" Burst types defined in 3GPP TS 45.002 """
	DUMMY	= ("DB") # Dummy burst (5.2.6)
	SYNC	= ("SB") # Synchronization Burst (5.2.5)
	FREQ	= ("FB") # Frequency correction Burst (5.2.4)
	ACCESS	= ("AB") # Access Burst (5.2.7)
	NORMAL	= ("NB") # Normal Burst (5.2.3)
	# HSR	= ("HB") # Higher symbol rate burst (5.2.3a)

class TrainingSeqGMSK(Enum):
	""" Training Sequences defined in 3GPP TS 45.002 """

	# Training Sequences for Access Burst (table 5.2.7-3)
	AB_TS0 = (0, BurstType.ACCESS, "01001011011111111001100110101010001111000")
	AB_TS1 = (1, BurstType.ACCESS, "01010100111110001000011000101111001001101")
	AB_TS2 = (2, BurstType.ACCESS, "11101111001001110101011000001101101110111")
	AB_TS4 = (4, BurstType.ACCESS, "11001001110001001110000000001101010110010")

	# Training Sequences for Access Burst (table 5.2.7-4)
	AB_TS3 = (3, BurstType.ACCESS, "10001000111010111011010000010000101100010")
	AB_TS5 = (5, BurstType.ACCESS, "01010000111111110101110101101100110010100")
	AB_TS6 = (6, BurstType.ACCESS, "01011110011101011110110100010011000010111")
	AB_TS7 = (7, BurstType.ACCESS, "01000010110000011101001010111011100010000")

	# Training Sequences for Synchronization Burst (table 5.2.5-3)
	SB_TS0 = (0, BurstType.SYNC, "1011100101100010000001000000111100101101010001010111011000011011")
	SB_TS1 = (1, BurstType.SYNC, "1110111001101011001010000011111011110100011111101100101100010101")
	SB_TS2 = (2, BurstType.SYNC, "1110110000110111010100010101101001111000000100000010001101001110")
	SB_TS3 = (3, BurstType.SYNC, "1011101000111101110101101111010010001011010000001000111010011000")

	# Training Sequences for Normal Burst (table 5.2.3a, TSC set 1)
	NB_TS0 = (0, BurstType.NORMAL, "00100101110000100010010111")
	NB_TS1 = (1, BurstType.NORMAL, "00101101110111100010110111")
	NB_TS2 = (2, BurstType.NORMAL, "01000011101110100100001110")
	NB_TS3 = (3, BurstType.NORMAL, "01000111101101000100011110")
	NB_TS4 = (4, BurstType.NORMAL, "00011010111001000001101011")
	NB_TS5 = (5, BurstType.NORMAL, "01001110101100000100111010")
	NB_TS6 = (6, BurstType.NORMAL, "10100111110110001010011111")
	NB_TS7 = (7, BurstType.NORMAL, "11101111000100101110111100")

	# TODO: more TSC sets from tables 5.2.3b-d

	def __init__(self, tsc, bt, seq_str, tsc_set = 0):
		# Training Sequence Code
		self.tsc = tsc
		# Burst type
		self.bt = bt

		# Training Sequence Code set
		# NOTE: unlike the specs. we count from zero
		self.tsc_set = tsc_set

		# Generate Training Sequence bits
		self.seq = [int(x) for x in seq_str]

	@classmethod
	def pick(self, burst):
		# Normal burst TS (26 bits)
		nb_seq = burst[3 + 57 + 1:][:26]
		# Access burst TS (41 bits)
		ab_seq = burst[8:][:41]
		# Sync Burst TS (64 bits)
		sb_seq = burst[3 + 39:][:64]

		for ts in list(self):
			# Ugly Python way of writing 'switch' statement
			if ts.bt is BurstType.NORMAL and ts.seq == nb_seq:
				return ts
			elif ts.bt is BurstType.ACCESS and ts.seq == ab_seq:
				return ts
			elif ts.bt is BurstType.SYNC and ts.seq == sb_seq:
				return ts

		return None

class HoppingParams:
	""" Hopping sequence generation as per 3GPP TS 45.002, section 6.2.3.

	Based on firmware/layer1/rfch.c:rfch_hop_seq_gen() by Sylvain Munaut.

	"""

	# Magic numbers for pseudo-random hopping sequence generation
	RNTABLE = [
		 48,  98,  63,   1,  36,  95,  78, 102,  94,  73,
		  0,  64,  25,  81,  76,  59, 124,  23, 104, 100,
		101,  47, 118,  85,  18,  56,  96,  86,  54,   2,
		 80,  34, 127,  13,   6,  89,  57, 103,  12,  74,
		 55, 111,  75,  38, 109,  71, 112,  29,  11,  88,
		 87,  19,   3,  68, 110,  26,  33,  31,   8,  45,
		 82,  58,  40, 107,  32,   5, 106,  92,  62,  67,
		 77, 108, 122,  37,  60,  66, 121,  42,  51, 126,
		117, 114,   4,  90,  43,  52,  53, 113, 120,  72,
		 16,  49,   7,  79, 119,  61,  22,  84,   9,  97,
		 91,  15,  21,  24,  46,  39,  93, 105,  65,  70,
		125,  99,  17, 123,
	]

	def __init__(self, hsn, maio, ma):
		# Make sure MA is not empty
		ma_len = len(ma)
		if ma_len == 0: # TODO: or rather > 1?
			raise ValueError("Mobile Allocation is empty")

		self.hsn = hsn
		self.maio = maio
		self.ma = ma

		# Pre-calculate 2 ** NBIN in advance
		self._pnm = (ma_len >> 0) | (ma_len >> 1) \
			  | (ma_len >> 2) | (ma_len >> 3) \
			  | (ma_len >> 4) | (ma_len >> 5) \
			  | (ma_len >> 6)

	def __str__(self):
		fmt = "hsn=%u, maio=%u, ma_len=%u"
		return fmt % (self.hsn, self.maio, len(self.ma))

	@staticmethod
	def fn2gsm_time(fn):
		t1 = fn // (26 * 51)
		t2 = fn % 26
		t3 = fn % 51
		tc = (fn // 51) % 8
		return (t1, t2, t3, tc)

	# Resolve current ARFCN using the given TDMA frame number
	def resolve(self, fn):
		# Cyclic hopping
		if self.hsn == 0:
			mai = (fn + self.maio) % len(self.ma)
			return self.ma[mai]

		# Pseudo random hopping
		(t1, t2, t3, tc) = self.fn2gsm_time(fn)
		ma_len = len(self.ma)

		rn_idx = (self.hsn ^ (t1 & 63)) + t3
		m = t2 + self.RNTABLE[rn_idx]
		mp = m & self._pnm

		s = mp if mp < ma_len else (mp + t3 & self._pnm) % ma_len
		mai = (s + self.maio) % ma_len
		return self.ma[mai]