3 Frame Structure

08.603GPPIn-band control of remote transcoders and rate adaptors for Enhanced Full Rate (EFR) and full rate traffic channelsTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

3.1 Frames for Speech Services

3.1.1 Frames for Full Rate and Enhanced Full Rate Speech

			Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	C14	C15
4	1	D1	D2	D3	D4	D5	D6	D7
5	D8	D9	D10	D11	D12	D13	D14	D15
6	1	D16	D17	D18	D19	D20	D21	D22
7	D23	D24	D25	D26	D27	D28	D29	D30
8	1	D31	D32	D33	D34	D35	D36	D37
9	D38	D39	D40	D41	D42	D43	D44	D45
10	1	D46	D47	D48	D49	D50	D51	D52
11	D53	D54	D55	D56	D57	D58	D59	D60
12	1	D61	D62	D63	D64	D65	D66	D67
13	D68	D69	D70	D71	D72	D73	D74	D75
14	1	D76	D77	D78	D79	D80	D81	D82
15	D83	D84	D85	D86	D87	D88	D89	D90
16	1	D91	D92	D93	D94	D95	D96	D97
17	D98	D99	D100	D101	D102	D103	D104	D105
18	1	D106	D107	D108	D109	D110	D111	D112
19	D113	D114	D115	D116	D117	D118	D119	D120
20	1	D121	D122	D123	D124	D125	D126	D127
21	D128	D129	D130	D131	D132	D133	D134	D135
22	1	D136	D137	D138	D139	D140	D141	D142
23	D143	D144	D145	D146	D147	D148	D149	D150
24	1	D151	D152	D153	D154	D155	D156	D157
25	D158	D159	D160	D161	D162	D163	D164	D165
26	1	D166	D167	D168	D169	D170	D171	D172
27	D173	D174	D175	D176	D177	D178	D179	D180
28	1	D181	D182	D183	D184	D185	D186	D187
29	D188	D189	D190	D191	D192	D193	D194	D195
30	1	D196	D197	D198	D199	D200	D201	D202
31	D203	D204	D205	D206	D207	D208	D209	D210
32	1	D211	D212	D213	D214	D215	D216	D217
33	D218	D219	D220	D221	D222	D223	D224	D225
34	1	D226	D227	D228	D229	D230	D231	D232
35	D233	D234	D235	D236	D237	D238	D239	D240
36	1	D241	D242	D243	D244	D245	D246	D247
37	D248	D249	D250	D251	D252	D253	D254	D255
38	1	D256	D257	D258	D259	D260	C16	C17
39	C18	C19	C20	C21	T1	T2	T3	T4

3.1.2 Frames for Adaptive Multi-Rate Speech

			Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	C14	C15
4	1	C16	C17	C18	C19	C20	C21	C22
5	C23	C24	C25	D1	D2	D3	D4	D5
6	1	D6	D7	D8	D9	D10	D11	D12
7	D13	D14	D15	D16	D17	D18	D19	D20
8	1	D21	D22	D23	D24	D25	D26	D27
9	D28	D29	D30	D31	D32	D33	D34	D35
10	1	D36	D37	D38	D39	D40	D41	D42
11	D43	D44	D45	D46	D47	D48	D49	D50
12	1	D52	D52	D53	D54	D55	D56	D57
13	D58	D59	D60	D61	D62	D63	D64	D65
14	1	D66	D67	D68	D69	D70	D71	D72
15	D73	D74	D75	D76	D77	D78	D79	D80
16	1	D81	D82	D83	D84	D85	D86	D87
17	D88	D89	D90	D91	D92	D93	D94	D95
18	1	D96	D97	D98	D99	D100	D101	D102
19	D103	D104	D105	D106	D107	D108	D109	D110
20	1	D111	D112	D113	D114	D115	D116	D117
21	D118	D119	D120	D121	D122	D123	D124	D125
22	1	D126	D127	D128	D129	D130	D131	D132
23	D133	D134	D135	D136	D137	D138	D139	D140
24	1	D141	D142	D143	D144	D145	D146	D147
25	D148	D149	D150	D151	D152	D153	D154	D155
26	1	D156	D157	D158	D159	D160	D161	D162
27	D163	D164	D165	D166	D167	D168	D169	D170
28	1	D171	D172	D173	D174	D175	D176	D177
29	D178	D179	D180	D181	D182	D183	D184	D185
30	1	D186	D187	D188	D189	D190	D191	D192
31	D193	D194	D195	D196	D197	D198	D199	D200
32	1	D201	D202	D203	D204	D205	D206	D207
33	D208	D209	D210	D211	D212	D213	D214	D215
34	1	D216	D217	D218	D219	D220	D221	D222
35	D223	D224	D225	D226	D227	D228	D229	D230
36	1	D231	D232	D233	D234	D235	D236	D237
37	D238	D239	D240	D241	D242	D243	D244	D245
38	1	D246	D247	D248	D249	D250	D251	D252
39	D253	D254	D255	D256	T1	T2	T3	T4

3.2 O&M Frames

			Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	C14	C15
4	1	D1	D2	D3	D4	D5	D6	D7
5	D8	D9	D10	D11	D12	D13	D14	D15
6	1	D16	D17	D18	D19	D20	D21	D22
7	D23	D24	D25	D26	D27	D28	D29	D30
8	1	D31	D32	D33	D34	D35	D36	D37
9	D38	D39	D40	D41	D42	D43	D44	D45
10	1	D46	D47	D48	D49	D50	D51	D52
11	D53	D54	D55	D56	D57	D58	D59	D60
12	1	D61	D62	D63	D64	D65	D66	D67
13	D68	D69	D70	D71	D72	D73	D74	D75
14	1	D76	D77	D78	D79	D80	D81	D82
15	D83	D84	D85	D86	D87	D88	D89	D90
16	1	D91	D92	D93	D94	D95	D96	D97
17	D98	D99	D100	D101	D102	D103	D104	D105
18	1	D106	D107	D108	D109	D110	D111	D112
19	D113	D114	D115	D116	D117	D118	D119	D120
20	1	D121	D122	D123	D124	D125	D126	D127
21	D128	D129	D130	D131	D132	D133	D134	D135
22	1	D136	D137	D138	D139	D140	D141	D142
23	D143	D144	D145	D146	D147	D148	D149	D150
24	1	D151	D152	D153	D154	D155	D156	D157
25	D158	D159	D160	D161	D162	D163	D164	D165
26	1	D166	D167	D168	D169	D170	D171	D172
27	D173	D174	D175	D176	D177	D178	D179	D180
28	1	D181	D182	D183	D184	D185	D186	D187
29	D188	D189	D190	D191	D192	D193	D194	D195
30	1	D196	D197	D198	D199	D200	D201	D202
31	D203	D204	D205	D206	D207	D208	D209	D210
32	1	D211	D212	D213	D214	D215	D216	D217
33	D218	D219	D220	D221	D222	D223	D224	D225
34	1	D226	D227	D228	D229	D230	D231	D232
35	D233	D234	D235	D236	D237	D238	D239	D240
36	1	D241	D242	D243	D244	D245	D246	D247
37	D248	D249	D250	D251	D252	D253	D254	D255
38	1	D256	D257	D258	D259	D260	D261	D262
39	D263	D264	S1	S2	S3	S4	S5	S6

3.3 Data Frames

3.3.1 Data Frame (for Synchronisation)

			Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	C14	C15
4	1							.
5	1							.
6	1							.
7	1	Data frame position 1
8	1	63 bits.
9	1	(72 bits including bit position 1)
10	1
11	1
12	1
13	1
14	1
15	1
161	1	Data frame position 2
17	1
18	1
19	1
20	1
21	1
22	1
23	1
24	1
25	1	Data frame position 3
26	1
27	1
28	1
29	1
30	1
31	1
32	1
33	1	Data frame position 4
34	1
35	1
36	1
37	1
38	1
39	1

3.3.2 Extended data frame (E-TRAU : data transport)

			Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	M1	M2
4	D1	D2	…
5
6
7		Data block of 288 data bits and M1, M2.
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						…	D287	D288

3.4 Idle Speech Frames

				Bit number
Octet no.	1	2	3	4	5	6	7	8
0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0
2	1	C1	C2	C3	C4	C5	C6	C7
3	C8	C9	C10	C11	C12	C13	C14	C15
4	1	1	1	1	1	1	1	1
5	1	1	1	1	1	1	1	1
6	1	1	1	1	1	1	1	1
7	1	1	1	1	1	1	1	1
8	1	1	1	1	1	1	1	1
9	1	1	1	1	1	1	1	1
10	1	1	1	1	1	1	1	1
11	1	1	1	1	1	1	1	1
12	1	1	1	1	1	1	1	1
13	1	1	1	1	1	1	1	1
14	1	1	1	1	1	1	1	1
15	1	1	1	1	1	1	1	1
16	1	1	1	1	1	1	1	1
17	1	1	1	1	1	1	1	1
18	1	1	1	1	1	1	1	1
19	1	1	1	1	1	1	1	1
20	1	1	1	1	1	1	1	1
21	1	1	1	1	1	1	1	1
22	1	1	1	1	1	1	1	1
23	1	1	1	1	1	1	1	1
24	1	1	1	1	1	1	1	1
25	1	1	1	1	1	1	1	1
26	1	1	1	1	1	1	1	1
27	1	1	1	1	1	1	1	1
28	1	1	1	1	1	1	1	1
29	1	1	1	1	1	1	1	1
30	1	1	1	1	1	1	1	1
31	1	1	1	1	1	1	1	1
32	1	1	1	1	1	1	1	1
33	1	1	1	1	1	1	1	1
34	1	1	1	1	1	1	1	1
35	1	1	1	1	1	1	1	1
36	1	1	1	1	1	1	1	1
37	1	1	1	1	1	1	1	1
38	1	1	1	1	1	1	C16	C17
39	C18	C19	C20	C21	T1	T2	T3	T4

3.5 Coding

In the following clauses, the coding of the frames is described. Any spare or not used control bits should be coded binary "1".

For all frame types the octet 0, 1 and the first bit of octets 2, 4, 6, 8, … 38 are used as frame sync.

3.5.1 Coding of Frames for Speech Services

3.5.1.1 Coding of Frames for Full Rate and Enhanced Full Rate Speech

3.5.1.1.1 Coding of Control bits (C-bits)

Description	Uplink	Downlink

	C1C2C3C4 C5	C1C2C3C4 C5
Frame type FR	Speech: 0 0 0 1 0.	Speech: 1 1 1 0 0
(Bits C1 – C5). EFR	Speech: 1 1 0 1 0	Speech: 1 1 0 1 0

Time	Binary number indicating the	Binary number indicating
Alignment	required timing adjustment to	the timing adjustment made.
(Bits C6 – C11)	be made in steps of 250/500 s.

	The following values apply for the coding
	C6C7 . . . C11
	0 0 0 0 0 0 No change in frame timing
	0 0 0 0 0 1 Delay frame 1 x 500 s
	0 0 0 0 1 0 Delay frame 2 x 500 s
	. . . ….
	. . . ….
	1 0 0 1 1 1 Delay frame 39 x 500 s
	1 0 1 0 0 0 Not used
	. . . ….
	1 1 1 1 0 1 Not used
	1 1 1 1 1 0 Delay frame 1 x 250 s
	1 1 1 1 1 1 Advance frame 250 s

Frame indicators. The definition	C12: BFI	C12 – C15: Spare
and coding of these indicators	0 : BFI = 0
are given in GSM 06.31.	1 : BFI = 1	IF FR. Speech

	C13 C14: SID	ELSE
Bits C12 – C16	0 0 :SID = 0	C12: UFE
	0 1 :SID = 1	0 :UFE=0 bad uplink frame
	1 0 :SID = 2	1 : UFE=1 good up-link frame
Downlink
Uplink Frame Error	C15: TAF
(UFE) C12	0 : TAF = 0
(see clause 4.8.3)	1 : TAF = 1	C13 – C15: spare

	C16: Spare	C16: SP
		0 : SP = 0
		1 : SP = 1

DTX indicator	C17: DTXd	C17: Spare
	0 : DTX not applied
	1 : DTX applied

Bits C18 – C21	Spare	Spare

3.5.1.1.2 Coding of Data Bits (D-bits)

For Full Rate Speech:

Bits D1 .. D260: Speech block transferred in the same order as output from the transcoder (see GSM 06.10).

For Enhanced Full Rate Speech:

The speech block is subdivided in five subsets. The order within a given subset is the same as output from the transcoder (see ETS 300 726, GSM 06.60). Three parity bits are added at the end of each sub-set.

These parity bits are added to the bits of the subset, according to a degenerate (shortened) cyclic code using the generator polynomial:

g(D) = D³ + D + 1

The encoding of the cyclic code is performed in a systematic form which means that, in GF(2), the polynomial:

d(m)Dⁿ + d(m+1)D^n‑1 + ……+ d(m + n‑3)D³ + p(0)D² + p(1)D + p(2)

where p(0), p(1), p(2) are the parity bits, when divided by g(D), yields a remainder equal to:

1 + D + D²

For every CRC, the transmission order is p(0) first followed by p(1) and p(2) successively.

Bit D1 : spare (binary "1").

Bits D2…D39 : Indexes of the LSF submatrices.

Bits D40…D42 : CRC over bits D1 to D22, D25 to D27 and D29.

Bits D43…D95 : Indexes of the parameters of first sub-frame.

Bits D96…D98 : CRC over bits D43 to D52, D91 and D92.

Bits D99…D148 : Indexes of the parameters of second sub-frame.

Bits D149…D151 : CRC over bits D99 to D103, D105, D144 and D145.

Bits D152…D204 : Indexes of the parameters of third sub-frame.

Bits D205…D207 : CRC over bits D152 to D161, D200 and D201.

Bits D208…D257 : Indexes of the parameters of fourth sub-frame.

Bits D258…D260 : CRC over bits D208 to D212, D214, D253 and D254.

3.5.1.1.3 Time Alignment Bits (T1…T4)

Bits T1 .. T4: Bits positioned at the end of the downlink frames. If the timing of the frame is to be advanced 250 µs, these 4 bits are not transferred in order to reduce the frame length accordingly. When transferred the bits are set to binary "1".

3.5.1.2 Coding of Frames for Adaptive Multi-Rate Speech

3.5.1.2.1 Coding of Control bits (C-bits)

Control Bits	Description Uplink	Description Downlink
C1…C5	Frame_Type (Codec_Type)	Frame_Type (Codec_Type)
C6…C11	Time Alignment Command (TAC) or Phase Alignment Control (PAC) or TFO Information or Handover Information	Time Alignment Command (TAC) or Phase Alignment Control (PAC) or TFO Information or Handover Information
C12	Request or Indication Flag (RIF)	Request or Indication Flag (RIF)
C13	spare, set to 1	Uplink Frame Error (UFE)
C14 . C15 . C16	Config_Prot	Config_Prot
C17 . C18	Message_No	Message_No
C19	DTX in downlink requested (DTXd)	spare, reserved for TFO (see 08.62)
C20	TFO Enabled (TFOE)	spare, reserved for TFO (see 08.62)
C21 . C22	Frame_Classification, Rx_Type	Frame_Classification, Tx_Type
C23 . C24 . C25	Codec_Mode_Indication (RIF == 0) or Codec_Mode_Request (RIF == 1) or 0.0.0 (Frame_Classification == 0.0)	Codec_Mode_Indication (RIF == 0) or Codec_Mode_Request (RIF == 1) or 0.0.0 (Frame_Classification == 0.0)

Detailed Description:

Frame Type:
The coding of the Frame_Type (also called "Codec_Type") for AMR is identical in uplink and downlink.
C1…C5:
0.0.1.1.0: Adaptive Multi-Rate Codec.

Time Alignment Field:
The Time Alignment Field (Bits C6…C11) is used to carry either the Time Alignment Command (TAC), the Phase Alignment Control (PAC) or the TFO and Handover Information. The Time Alignment Command is coded as for the Full Rate and Enhanced Full Rate (clause 3.5.1.1.1).

Time Alignment Command (TAC):
In the uplink direction (BTS to TRAU) the TAC indicates the required timing adjustment for the downlink TRAU frame to be made by the TRAU in 250/500ms steps.
C6…C11:
0.0.0.0.0.0 No change in frame timing
0.0.0.0.0.1 Delay frame 1 x 500ms (send four additional T-Bit-pairs after the end of the TRAU Frame)
0.0.0.0.1.0 Delay frame 2 x 500ms (send eight additional T-Bit-pairs after the end of the TRAU Frame)
…
1.0.0.1.1.1 Delay frame 39 x 500ms (send 156 additional T-Bit-pairs after the end of the TRAU Frame)
(1.0.1.0.0.0 to 1.1.0.1.1.1: 16 code-points, unused, reserved)
(1.1.1.0.0.0 to 1.1.1.0.1.1: 4 code-points, reserved for TFO and Handover Information)
(1.1.1.1.0.0 reserved for Handover Information)
(1.1.1.1.0.1 reserved for AMR CMI/CMR Phase Alignment Command (PAC), no change in frame timing)
1.1.1.1.1.0 Delay frame by 250ms (send two additional T-Bit-pairs after the end of the TRAU Frame)
1.1.1.1.1.1 Advance frame by 250ms (do not send the two T-Bit-pairs at the end of the TRAU Frame).

Phase Alignment Command (PAC) (useful when TFO is not supported or disabled):
The Phase Alignment Command (PAC) can be used by the BTS to command the TRAU to change (invert) the phase of CMI/CMR, respectively RIF, in downlink TRAU frames, see clause 4.6.1.2.1.
C6…C11:
1.1.1.1.0.1 AMR CMI/CMR Phase Alignment Command (PAC), no change in frame timing.

In No_Speech frames the Phase Alignment Command may optionally be transmitted by one additional bit (PAB, see subclause 3.5.1.2.2) that allows a direct time and phase alignment in one step.

TFO Information (recommended when TFO is supported, see GSM 08.62):
C6…C11
1.1.1.0.0.0
1.1.1.0.0.1
1.1.1.0.1.0
These three codes are reserved for Tandem Free Operation (see GSM 08.62). They result in no change in frame timing. If the BTS does not support TFO or TFO is disabled these codes shall not be used. The procedure to exchange this information between BTS and TRAU is described in GSM 08.62.

Handover Information (recommended when Pre-Handover Warning is supported):
C6…C11:
1.1.1.0.1.1 Handover_Soon Handover is to be expected soon.

1.1.1.1.0.0 Handover_Complete
These codes are used, if the BSC and BTS support Pre-Handover Warning. They result in no change in frame timing. The BTS shall repeat this information as long as it is valid in every frame where no other information has to be transmitted in the Time Alignment Field. The TRAU shall not reflect or acknowledge it. The procedure to exchange this information in case of TFO is described in GSM 08.62.

Request or Indication Flag (RIF):
This flag indicates the phase of the Codec_Mode_Indication (RIF == 0) respectively the Codec_Mode_Request (RIF == 1). It has the same meaning in uplink and in downlink. Typically this flag toggles every frame. Exceptions may occur at handover and CMI/CMR phase alignment, see clause 4.6.1.2.1.

Uplink Frame Error (UFE):
In downlink the UFE indicates that the most recently received uplink TRAU frame had detectable errors.
In uplink this bit shall be set to "1".
UFE == 0: "Uplink Frame received with Errors";
UFE == 1: "Uplink Frame received without Errors".
Note: the UFE is not related to the frame classification (Rx_Type) as computed by the BTS radio receiver. It is related to inconsistencies in the TRAU frame synchronization, control bits or CRCs within the TRAU frame.

Config_Prot
This field is reserved for the Configuration Protocol in case of Tandem Free Operation (see GSM 08.62). If the BTS does not support TFO or TFO is disabled, then this field shall be set to "0.0.0".

Message_No
This field is reserved for the Configuration Protocol in case of Tandem Free Operation (see GSM 08.62). If the BTS does not support TFO or TFO is disabled, then this field shall be set to "0.0".

DTX in downlink requested (DTXd)
See clause 4.6.2.2.

TFO Enabled (TFOE)
This bit enables or disables Tandem Free Operation in the TRAU. If the BTS does not support TFO or TFO is disabled, then this bit shall be set to "0". Coding:
TFOE == 0: TFO Disabled;
TFOE == 1: TFO Enabled.

Frame_Classification:
This field classifies the contents of the TRAU frame as seen by the radio receiver, see GSM 06.93:
C21…C22:
1 1 "Speech_Good" the frame can be decoded without restriction
1 0 "Speech_Degraded" the frame might contain undetected errors
0 1 "Speech_Bad" the frame contains errors that can not be corrected
0 0 "No_Speech" the frame is not a speech frame, see below.

In the uplink direction the Frame_Classification is also called "Rx_Type" and is always set by the BTS.

In the downlink direction the Frame_Classification is also called "Tx_Type".
If Tandem Free Operation is not ongoing, then the codes "Speech_Degraded", and "Speech_Bad" shall not be used in the downlink direction. If Tandem Free Operation is ongoing, then all codes may be used in the downlink direction. For the handling within the downlink BTS, see GSM 08.62).

Codec_Mode_Indication / Codec_Mode_Request:
This 3-bit field has three different meanings, depending on the Frame_Classification field and the Request_or_Indication_Flag (RIF):
If Frame_Classification is different than "0.0" then this field contains
either the Codec_Mode_Indication (CMI), if RIF equals 0;
or the Codec_Mode_Request (CMR), if RIF equals 1.
If Frame_Classification is equal to "0.0", i.e. when a No_Speech frame is transmitted, then this field shall be set to "0.0.0". CMI and CMR are then simultaneously transmitted in the Data Bits.
The coding is identical in uplink and downlink.
C23 . C24. C25:
0 0 0 Codec_Mode 4,75 kBit/s
0 0 1 Codec_Mode 5,15 kBit/s
0 1 0 Codec_Mode 5,90 kBit/s
0 1 1 Codec_Mode 6,70 kBit/s
1 0 0 Codec_Mode 7,40 kBit/s
1 0 1 Codec_Mode 7,95 kBit/s
1 1 0 Codec_Mode 10,2 kBit/s
1 1 1 Codec_Mode 12,2 kBit/s
The CMI indicates the Codec_Mode to be used for decoding the associated speech parameters in the same and the next frame. The CMR indicates the Codec_Mode to be used for encoding in the opposite direction.

NOTE 1: In the TRAU frames, the Codec_Mode_Request, respectively the Codec_Mode_Indication are coded absolutely (three bits for eight possible modes). On the radio interface, because of bandwidth limitation, these parameters are coded with two bits only. The CCU shall perform the required translation.

NOTE 2: In case of no Tandem Free Operation the uplink CMR is a Codec_Mode_Command (CMC) from the BTS to the TRAU and the TRAU shall try to follow the command as soon as possible. The only allowed exception is in case of DTX when SID or No_Data frames can be used during speech pauses. In the downlink direction the CMR shall be set by the TRAU to "1.1.1".

NOTE 3: In case of an ongoing Tandem Free Operation, the local uplink CMR is an indication from the local BTS to the TRAU, respectively to the distant BTS, on the highest allowed Codec_Mode in the local downlink direction. This indication must be combined with the corresponding CMR in the distant uplink direction to set the Codec Mode to use in that direction. The local downlink CMR is the indication from the distant radio link on the highest allowed Codec_Mode in the distant downlink direction. This indication must be combined with the corresponding CMR for the local uplink direction, see GSM 05.09 and 08.62.

3.5.1.2.2 Coding of Data bits (D-bits)

In Codec_Mode 10,2 kBit/s the bits D1…D20 and D234…D253 are reserved for Tandem Free Operation In all Codec_Modes below 10,2 kBit/s and in all No_Speech frames the bits D1…D31 (31 bits) and D203…D256 (54 bits) are reserved for Tandem Free Operation (see GSM 08.62).
In No_Speech frames additionally bits D44…D57 (14 bits) are reserved for TFO as well.

If the BTS does not support TFO or TFO is disabled, then the bits in these fields shall all be set to "1".

Coding of Speech Frames:
The contents of the Data bits for all eight AMR Codec_Modes are defined in the following, in cases when the Frame_Classification is either set to Speech_Good, Speech_Degraded, or Speech_Bad. The speech block is subdivided into four subsets. The order within a given subset is the same as output from the transcoder (see GSM 06.90). The four times three parity bits (CRC1 to CRC4), added at the end of each subset, are generated using the same cyclic code as defined for the Enhanced Full Rate (see clause 3.5.1.1.2). The TRAU frame formats in uplink and downlink direction are identical.

AMR_Mode 12,2 kBit/s, see GSM 06.90:
D1…D38: Indexes of the LSF submatrices (s1…s38)
D39…D91: Indexes of the parameters of first sub-frame (s39…s91)
D92…D94: CRC1 over bits C1…C25, s1…s29, s39…s50, s87…s89.
D95…D144: Indexes of the parameters of second sub-frame (s92…s141)
D145…D147: CRC2 over bits s92…s100, s137…s139.
D148…D200: Indexes of the parameters of third sub-frame (s142…s194)
D201…D203: CRC3 over bits s142…s153, s190…s192.
D204…D253: Indexes of the parameters of fourth sub-frame (s195….s244)
D254…D256: CRC4 over bits s195…s199, s201…s203, s240…s242.

AMR_Mode 10,2 kBit/s, see GSM 06.90:
D21…D46: Indexes of the LSF submatrices (s1…s26)
D47…D92: Indexes of the parameters of first sub-frame (s27…s72)
D93…D95: CRC1 over bits C1…C25, D1…D20, s1…s25, s27…s34, s66, s67, s69, s70.
D96…D138: Indexes of the parameters of second sub-frame (s73…s115)
D139…D141: CRC2 over bits s73…s76, s109, s110, s112, s113.
D142…D187: Indexes of the parameters of third sub-frame (s116…s161)
D188…D190: CRC3 over bits s116…s123, s155, s156, s158, s159.
D191…D233: Indexes of the parameters of fourth sub-frame (s162…s204)
D254…D256: CRC4 over bits s162…s165, s198, s199, s201, s202, D234…D253.

AMR_Mode 7,95 kBit/s, see GSM 06.90:
D32…D58: Indexes of the LSF submatrices (s1…s27)
D59…D92: Indexes of the parameters of first sub-frame (s28…s61)
D93…D95: CRC1 over bits C1…C25, s1…s35, s53, s54, s57, s60.
D96…D127: Indexes of the parameters of second sub-frame (s62…s93)
D128…D130: CRC2 over bits s62…s65, s85, s86, s89…s92.
D131…D164: Indexes of the parameters of third sub-frame (s94…s127)
D165…D167: CRC3 over bits s94…s101, s119, s120, s123…s126.
D168…D199: Indexes of the parameters of fourth sub-frame (s128…s159)
D200…D202: CRC4 over bits s128…s131, s151, s152, s155…s158.

AMR_Mode 7,40 kBit/s, see GSM 06.90:
D32…34 spare (3 bits); set to "1"
D35…D60: Indexes of the LSF submatrices (s1…s26)
D61…D92: Indexes of the parameters of first sub-frame (s27…s58)
D93…D95: CRC1: bits C1…C25, s1…s20, s22…s24, s27…s32, s52, s53, s55…s57.
D96…D124: Indexes of the parameters of second sub-frame (s59…s87)
D125…D127: CRC2 over bits s59…s61, s81, s82, s84…s86.
D128…D159: Indexes of the parameters of third sub-frame (s88…s119)
D160…D162: CRC3 over bits s88…s93, s113, s114, s116…s118.
D163…D191: Indexes of the parameters of fourth sub-frame (s120…s148)
D192…D194: CRC4 over bits s120…s122, s142, s143, s145, s146.
D195…D202: spare (8 bits); set to "1".

AMR_Mode 6,70 kBit/s, see GSM 06.90:
D32…D37: spare (6 bits); set to "1"
D38…D63: Indexes of the LSF submatrices (s1…s26)
D64…D92: Indexes of the parameters of first sub-frame (s27…s55)
D93…D95: CRC1 over bits C1…C25, s1…s17, s20, s24, s27…s34, s49…s53.
D96…D120: Indexes of the parameters of second sub-frame (s56…s80)
D121…D123: CRC2 over bits s56…s59, s74…s78.
D124…D152: Indexes of the parameters of third sub-frame (s81…s109)
D153…D155: CRC3 over bits s81…s88, s103…s107.
D156…D180: Indexes of the parameters of fourth sub-frame (s110…s134)
D181…D183: CRC4 over bits s110…s113, s128…s132.
D184…D202: spare (19 bits); set to "1".

AMR_Mode 5,90 kBit/s, see GSM 06.90:
D32…D41: spare (10 bits); set to "1"
D42…D67: Indexes of the LSF submatrices (s1…s26)
D68…D92: Indexes of the parameters of first sub-frame (s27…s51)
D93…D95: CRC1 over bits C1…C25, s1…s17, s27…s34, s48…s51.
D96…D116: Indexes of the parameters of second sub-frame (s52…s72)
D117…D119: CRC2 over bits s52…s54, s69…s72.
D120…D144: Indexes of the parameters of third sub-frame (s73…s97)
D145…D147: CRC3 over bits s73…s80, s94…s97.
D148…D168: Indexes of the parameters of fourth sub-frame (s98…s118)
D169…D171: CRC4 over bits s98…s100, s115…s118.
D172…D202: spare (31 bits); set to "1".

AMR_Mode 5,15 kBit/s, see GSM 06.90:
D32…D46 spare (15 bits); set to "1"
D47…D69: Indexes of the LSF submatrices (s1…s23)
D70…D92: Indexes of the parameters of first sub-frame (s24…s46)
D93…D95: CRC1 over bits C1…C25, s1…s16, s19…s29, s42…s46.
D96…D114: Indexes of the parameters of second sub-frame (s47…s65)
D115…D117: CRC2 over bits s47…s48, s61…s65.
D118…D136: Indexes of the parameters of third sub-frame (s66…s84)
D137…D139: CRC3 over bits s66…s67, s80…s84.
D140…D158: Indexes of the parameters of fourth sub-frame (s85…s103)
D159…D161: CRC4 over bits s85…s86, s99…s103.
D162…D202: spare (41 bits); set to "1".

AMR_Mode 4,75 kBit/s, see GSM 06.90:
D32…D44: spare (13 bits); set to "1"
D45…D67: Indexes of the LSF submatrices (s1…s23)
D68…D92: Indexes of the parameters of first sub-frame (s24…s48)
D93…D95: CRC1 over bits C1…C25, s1…s16, s18, s19, s21…s29, s45…s48.
D96…D108: Indexes of the parameters of second sub-frame (s49…s61)
D109…D111: CRC2 over bits s49,s50.
D112…D132: Indexes of the parameters of third sub-frame (s62…s82)
D133…D135: CRC3 over bits s62, s63, s79…s82.
D136…D148: Indexes of the parameters of fourth sub-frame (s83…s95)
D149…D151: CRC4 over bits s83, s84.
D152…D202: spare (51 bits); set to "1".

Coding of No_Speech Frames:
The following tables define the contents of the Data bits when the Frame_Classification is set to "No_Speech". The three parity bits (CRC1) added are generated using the same cyclic code as defined for the Enhanced Full Rate (see clause 3.5.1.1.2). The TRAU Frame Formats in uplink and downlink direction are identical.

SID_Update and SID_Bad Frame:
D32…D34: No_Speech_Classification D35…D37: Codec_Mode_Indication_abs
D38…D40: Codec_Mode_Request_abs
D41: PAB: Phase Alignment Bit (optional)
D42…D43: TAE: Time Alignment Extension (optional)
D44…D57: reserved for TFO
D58…D60: Moving average predictor, initial values (s1…s3)
D61…D86: Indexes of LSF submatrices (s4…s29)
D87…D92: Logarithmic frame energy (s30…s35)
D93…D95: CRC1 over bits C1…C25, D32…D92.
D96…D207: spare (112 bits); set to "1".

No_Data, SID_First and Onset Frame:
Bits D32…D34: No_Speech_Classification Bits D35…D37: Codec_Mode_Indication_abs
Bits D38…D40: Codec_Mode_Request_abs
Bit D41: PAB: Phase Alignment Bit (optional)

Bits D42…D43: TAE: Time Alignment Extension (optional)
Bits D44…D57: reserved for TFO
Bits D58…D92: spare (35 bits); set to "1" Bits D93…D95: CRC1 over bits C1…C25, D32…D92.
Bits D96…D207: spare (112 bits); set to "1".

No_Speech_Classification:
If the Frame_Classification is set to "0.0", then the TRAU frame contains no speech parameters. The No_Speech_Classification is coded in the D-Bits:
D32…D34:
1.1.1: Sid_First
1.1.0: Onset
1.0.1: Sid_Update
1.0.0: Sid_Bad (SID_Update with bad parameters)
0.1.1: spare
0.1.0: spare
0.0.1: spare
0.0.0: No_Data (nothing received or frame has been stolen, e.g. by FACCH or RATSCCH).

Codec_Mode_Indication_abs (CMI_abs):
The meaning in uplink and downlink is identical. In No_Speech frames the CMI is always transmitted, independent of the setting of the RIF bit. Coding:
D35 . D36 . D37:
0.0.0 Codec_Mode 4,75 kBit/s
0.0.1 Codec_Mode 5,15 kBit/s
0.1.0 Codec_Mode 5,90 kBit/s
0.1.1 Codec_Mode 6,70 kBit/s
1.0.0 Codec_Mode 7,40 kBit/s
1.0.1 Codec_Mode 7,95 kBit/s
1.1.0 Codec_Mode 10,2 kBit/s
1.1.1 Codec_Mode 12,2 kBit/s

Codec_Mode_Request_abs (CMR_abs):
The meaning in uplink and downlink is identical. In No_Speech frames the CMR is always transmitted, independent of the setting of the RIF bit. Coding:
D38 . D39 . D40:
0.0.0 Codec_Mode 4,75 kBit/s
0.0.1 Codec_Mode 5,15 kBit/s
0.1.0 Codec_Mode 5,90 kBit/s
0.1.1 Codec_Mode 6,70 kBit/s
1.0.0 Codec_Mode 7,40 kBit/s
1.0.1 Codec_Mode 7,95 kBit/s
1.1.0 Codec_Mode 10,2 kBit/s
1.1.1 Codec_Mode 12,2 kBit/s

Phase Alignment Bit (PAB):
This bit is defined only in No_Speech frames. It is optional and shall be set to "0", if not used.
The PAB has exactly the same meaning and function as the Phase Alignment Command (PAC). For the exact procedure see clause 4.6.1.2.1.
PAB set to 0: CMI/CMR phase in downlink TRAU frames shall not be changed
PAB set to 1: CMI/CMR phase in downlink TRAU frames shall be inverted.
PAB shall only be used together with TAC values between 0.0.0.0.0.0 ("No change in frame timing") and 1.0.0.1.1.1 ("Delay frame 39 x 500ms").

Time Alignment Extension (TAE):
The TAE specifies optionally a Time Alignment Extension. Coding:
D42 . D43: Meaning:
0.0: No additional delay with respect to the Time Alignment Command
0.1 Additional delay of 125 µs
1.0 Additional delay of 250 µs
1.1 Additional delay of 375 µs
TAE together with the Time Alignment Command (TAC) allow a "one step" time alignment of 125 µs accuracy in No_Speech frames. TAE shall only be used together with TAC values between 0.0.0.0.0.0 ("No change in frame timing") and 1.0.0.1.1.1 ("Delay frame 39 x 500ms").
The TAC_TAE combination 0.0.0.0.0.0_0.1 shall be interpreted as "Delay frame by 125ms".
The TAC_TAE combination 1.0.0.1.1.1_1.0 shall be interpreted as "Advance frame by 250ms".
The TAC_TAE combination 1.0.0.1.1.1_1.1 shall be interpreted as "Advance frame by 125ms".

3.5.1.2.3 Time Alignment Bits (T1…T4)

The coding and meaning is as described in 3.5.1.1.3 (Time Alignment Bits).

3.5.2 Coding of O&M Frames

Control bits (C-bits):

Description	Uplink	Downlink
	C1C2C3C4 C5	C1C2C3C4 C5
Frame type	0 0 1 0 1 : O&M	1 1 0 1 1 : O&M
Bits C1 – C5
Bits C6 – C15	Spare	Spare

Data Bits (D-bits):

Bits D1 .. D264: Bits used for transfer of O&M information. The coding and use of these bits are left to the manufacturer of the BSC/TRAU.

Spare Bits:

Bits S1 .. S6: Spare

3.5.3 Coding of Data Frames

Control bits (C-bits):

Description	Uplink	Downlink
Frame type.	C1C2C3C4 C5	C1C2C3C4 C5
Bits C1 – C5	0 1 0 0 0 : Data	1 0 1 1 0 : Data
	except 14.5	except 14.5

	1 0 1 0 0 : Data14.5 (note)	1 0 1 0 0 : Data 14.5 (note)
Intermediate RA bit	0: 8 kbit/s	0: 8 kbit/s
rate.	1: 16 kbit/s	1: 16 kbit/s
Bit C6
for data services
except 14.5
Spare	Spare	Spare
for Data 14.5
Bits C7 – C15	Spare	Spare
NOTE: The Data frame is in case of data 14.5 kbit/s used only for synchronization purposes. The data bits are in this case set according to clause 4.5.1.

3.5.4 Coding of Extended Data Frames

Control bits (C-bits):

Description	Uplink	Downlink
Frame type.	C1C2C3C4 C5	C1C2C3C4 C5
Bits C1 – C5	1 1 1 1 1 :	1 1 1 1 1 :
	Extended Data	Extended data
	frame 14.5 kbit/s	Frame 14.5

Bit C6
Idle/Data/UFE	Idle/data	UFE
	Frame indication

Bits C7 – C13	Spare	Bit C7 indicating idle/data frame. Bit C8-C13 spare

Multi Frame Structure	M1, M2	M1, M2
defined in GSM 04.21
Bits M1, M2

3.5.5 Coding of Idle Speech Frames

Control bits (C-bits):

Description	Uplink	Downlink
	C1C2C3C4 C5	C1C2C3C4 C5
Frame type.	1 0 0 0 0 : Idle Speech	0 1 1 1 0 : Idle Speech
Bits C1 – C5

Bits C6 – C21	Coding as for	Coding as for
	Speech frames.	Speech frames.

NOTE: Idle Speech frames shall not be used in AMR; instead Frame_Classification set to "No_Data" shall be applied.

Time Alignment Bits:

Bits T1 .. T4: Coding as for Speech frames.

3.6 Order of Bit Transmission

The order of bit transmission is:

The first octet is transferred first with the bit no. 1 first, bit no. 2 next etc.