5 Physical channels

05.023GPPMultiplexing and Multiple Access on the Radio PathTS

5.1 General

A physical channel uses a combination of frequency and time division multiplexing and is defined as a sequence of radio frequency channels and time slots. The complete definition of a particular physical channel consists of a description in the frequency domain, and a description in the time domain.

The description in the frequency domain is addressed in clause 5.4; the description in the time domain is addressed in clause 5.5.

5.2 Bursts

5.2.1 General

A burst is a period of RF carrier which is modulated by a data stream. A burst therefore represents the physical content of a timeslot.

5.2.2 Types of burst and burst timing

A timeslot is divided into 156.,25 symbol periods.

For GMSK modulation (see 05.04) a symbol is equivalent to a bit. A particular bit period within a timeslot is referenced by a bit number (BN), with the first bit period being numbered 0, and the last (1/4) bit period being numbered 156.

For 8PSK modulation (see 05.04) one symbol corresponds to three bits. A particular bit period within a timeslot is referenced by a bit number (BN), with the first bit being numbered 0, and the last (3/4) bit being numbered 468. The bits are mapped to symbols in ascending order according to 05.04.

In the clauses following the transmission timing of a burst within a timeslot is defined in terms of bit number. The bit with the lowest bit number is transmitted first.

Different types of burst exist in the system. One characteristic of a burst is its useful duration. The present document, in the clauses following, defines full bursts of 147 symbols useful duration, and a short burst of 87 symbols useful duration. The useful part of a burst is defined as beginning from half way through symbol number 0. The definition of the useful part of a burst needs to be considered in conjunction with the requirements placed on the phase and amplitude characteristics of a burst as specified in GSM 05.04 and 05.05.

The period between bursts appearing in successive timeslots is termed the guard period. Subclause 5.2.8 details constraints which relate to the guard period.

Normal burst (NB)

Normal burst for GMSK

Bit Number (BN)

Length of field

Contents of field

Definition

0  

‑  2

3

tail bits

(below)

3  

‑  60

58

encrypted bits (e0 . e57)

05.03

61  

‑  86

26

training sequence bits

(below)

87  

‑  144

58

encrypted bits (e58 . e115)

05.03

145  

‑  147

3

tail bits

(below)

(148  

‑  156

8,25

guard period (bits)

clause 5.2.8)

‑ where the "tail bits" are defined as modulating bits with states as follows:

(BN0, BN1, BN2) = (0, 0, 0) and

(BN145, BN146, BN147) = (0, 0, 0)

  • where the "training sequence bits" are defined as modulating bits with states as given in the following table according to the training sequence code, TSC. For broadcast and common control channels, the TSC must be equal to the BCC, as defined in GSM 03.03 and as described in this technical specification in clause 3.3.2. In networks supporting E-OTD Location services (see GSM 03.71 Annex C), the TSC shall be equal to the BCC for all normal bursts on BCCH frequencies.

NOTE: For COMPACT, for PDTCH/PACCH on primary and secondary carriers that are indicated in EXT_FREQUENCY_LIST by parameter INT_FREQUENCY and in INT_MEAS_CHAN_LIST (see clauses 10.1.5 and 10.2.3.2.2 of GSM 05.08), the TSCs should be equal to the BCC, as defined in GSM 03.03 and as described in this technical specification in clause 3.3.2, otherwise the accuracy of interference measurement reporting may be compromised.

  • For CTS control channels, the TSC shall be defined by the 3 LSBs (BN3, BN2, BN1) of the FPBI (specified in GSM 03.03).

Training

Training sequence bits

Sequence

(BN61, BN62 .. BN86)

Code (TSC)

    0

(0,0,1,0,0,1,0,1,1,1,0,0,0,0,1,0,0,0,1,0,0,1,0,1,1,1)

    1

(0,0,1,0,1,1,0,1,1,1,0,1,1,1,1,0,0,0,1,0,1,1,0,1,1,1)

    2

(0,1,0,0,0,0,1,1,1,0,1,1,1,0,1,0,0,1,0,0,0,0,1,1,1,0)

    3

(0,1,0,0,0,1,1,1,1,0,1,1,0,1,0,0,0,1,0,0,0,1,1,1,1,0)

    4

(0,0,0,1,1,0,1,0,1,1,1,0,0,1,0,0,0,0,0,1,1,0,1,0,1,1)

    5

(0,1,0,0,1,1,1,0,1,0,1,1,0,0,0,0,0,1,0,0,1,1,1,0,1,0)

    6

(1,0,1,0,0,1,1,1,1,1,0,1,1,0,0,0,1,0,1,0,0,1,1,1,1,1)

    7

(1,1,1,0,1,1,1,1,0,0,0,1,0,0,1,0,1,1,1,0,1,1,1,1,0,0)

Under certain circumstances only half the encrypted bits present in a normal burst will contain complete information. For downlink DTX operation on TCH‑FS and TCH‑HS, when a traffic frame (as defined in GSM 06.31) is scheduled for transmission and one of its adjacent traffic frames is not scheduled for transmission, the other half of the encrypted bits in the normal bursts associated with the scheduled traffic frame shall contain partial SID information from any associated SID frame, with the appropriate stealing flags BN60 or BN87 set to 0. In other cases the binary state of the remaining bits is not specified.

Normal burst for 8PSK

Bit Number (BN)

Length of field
(bits)

Contents of field

Definition

0 – 8

9

tail bits

(below)

9 – 182

174

encrypted bits (e0 . e173)

05.03

183 – 260

78

training sequence bits

(below)

261 – 434

174

encrypted bits (e174 . e347)

05.03

435 – 443

9

tail bits

(below)

444 – 468

24.75

guard period

clause 5.2.8

‑ where the "tail bits" are defined as modulating bits with states as follows (bits are grouped in symbols separated by ;):

(BN0, BN1 .. BN8) = (1,1,1;1,1,1;1,1,1) and

(BN435, BN436 .. BN443) = (1,1,1;1,1,1;1,1,1)

‑ where the "training sequence bits" are defined as modulating bits with states as given in the following table according to the training sequence code, TSC. For broadcast and common control channels, the TSC must be equal to the BCC, as defined in GSM 03.03 and as described in this technical specification in clause 3.3.2. In networks supporting E-OTD Location services (see GSM 03.71 Annex C), the TSC shall be equal to the BCC for all normal bursts on BCCH frequencies.

Training

Training sequence symbols

Sequence

(BN183, BN184 .. BN260)

Code (TSC)

    0

(1,1,1;1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;1,1,1;1,1,1;
1,1,1;0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1)

    1

(1,1,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;
0,0,1;0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1)

    2

(1,1,1;0,0,1;1,1,1;1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;
1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;1,1,1;1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1)

    3

(1,1,1;0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;1,1,1;
0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;1,1,1)

    4

(1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;1,1,1;
0,0,1;1,1,1;1,1,1;1,1,1;1,1,1;1,1,1;0,0,1;0,0,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1)

    5

(1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;1,1,1;
1,1,1;1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;1,1,1)

    6

(0,0,1;1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;
1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;0,0,1;1,1,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;0,0,1)

    7

(0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;1,1,1;1,1,1;1,1,1;0,0,1;1,1,1;
1,1,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;1,1,1;0,0,1;0,0,1;0,0,1;0,0,1;1,1,1;1,1,1)

5.2.4 Frequency correction burst (FB)

Bit Number

length

Contents

Definition

(BN)

of field

of field

0  

‑  2

3

tail bits

(below)

3  

‑  144

142

fixed bits

(below)

145  

‑  147

3

tail bits

(below)

(148  

‑  156

8,25

guard period (bits)

clause 5.2.8)

‑ where the "tail bits" are defined as modulating bits with states as follows:

(BN0, BN1, BN2) = (0, 0, 0) and

(BN145, BN146, BN147) = (0, 0, 0)

‑ where the "fixed bits" are defined as modulating bits with states as follows:

(BN3, BN4 .. BN144) = (0, 0 .. 0)

except for COMPACT frequency correction bursts where states are as follows:

(BN3, BN4, BN5, BN6 .. BN143, BN144) = (1, 0, 1, 0, … 1, 0)

NOTE: This burst is equivalent to unmodulated carrier with a +1 625/24 kHz frequency offset, above the nominal carrier frequency or for COMPACT, a -1 625/24 kHz frequency offset, below the nominal carrier frequency.

5.2.5 Synchronization Burst (SB)

Bit Number

Length

Contents

Definition

(BN)

of field

of field

0  

‑  2

3

tail bits

(below)

3  

‑  41

39

encrypted bits (e0 . e38)

05.03

42  

‑  105

64

extended training sequence bits

(below)

106  

‑  144

39

encrypted bits (e39 .. e77)

05.03

145  

‑  147

3

tail bits

(below)

(148  

‑  156

8,25

guard period (bits)

clause 5.2.8)

‑ where the "tail bits" are defined as modulating bits with states as follows:

(BN0, BN1, BN2) = (0, 0, 0) and

(BN145, BN146, BN147) = (0, 0, 0)

‑ where the "extended training sequence bits" are defined as modulating bits with states as follows:

(BN42, BN43 .. BN105) = (1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0,
0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0,
1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1)

except for CTS synchronisation bursts where states are as follows:

(BN42, BN43 .. BN105) = (1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0,

0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0,

1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1)

except for COMPACT synchronisation bursts furthermore, where states are as follows:

(BN42, BN43 .. BN105) = (1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1,

0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0)

5.2.6 Dummy burst

Bit Number

Length

Contents

Definition

(BN)

of field

of field

0  

‑  2

3

tail bits

(below)

3  

‑  144

142

mixed bits

(below)

145  

‑  147

3

tail bits

(below)

(148  

‑  156

8,25

guard period (bits)

clause 5.2.8)

‑ where the "tail bits" are defined as modulating bits with states as follows:

(BN0, BN1, BN2) = (0, 0, 0) and

(BN145, BN146, BN147) = (0, 0, 0)

‑ where the "mixed bits" are defined as modulating bits with states as follows:

(BN3, BN4 .. BN144) = (1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1,
0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0,
0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0,
0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1

0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0,
1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0,
1, 0, 1, 0)

5.2.7 Access burst (AB)

Bit Number

Length

Contents

Definition

(BN)

of field

of field

0  

‑  7

8

extended tail bits

(below)

8  

‑  48

41

synch. sequence bits

(below)

49  

‑  84

36

encrypted bits (e0..e35)

05.03

85  

‑  87

3

tail bits

(below)

(88  

‑  156

68,25

extended guard period (bits)

clause 5.2.8)

‑ where the "extended tail bits" are defined as modulating bits with the following states:

(BN0, BN1, BN2 .. BN7) = (0, 0, 1, 1, 1, 0, 1, 0)

‑ where the "tail bits" are defined as modulating bits with the following states:

(BN85, BN86, BN87) = (0, 0, 0)

‑ where the "synch. sequence bits" are defined as modulating bits with the following states, unless explicitly stated otherwise (see GSM 04.60):

(BN8, BN9 .. BN48) = (0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0,
1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0)

in case alternative training (synchronization) sequence "TS1" is used, the "synch. sequence bits" shall be defined as modulating bits with the following states:

(BN8, BN9 .. BN48) = (0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1,
0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1)

in case alternative training (synchronization) sequence "TS2" is used, the "synch. sequence bits" shall be defined as modulating bits with the following states:

(BN8, BN9 .. BN48) = (1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1,
0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1)

5.2.8 Guard period

The guard period is provided because it is required for the MSs that transmission be attenuated for the period between bursts with the necessary ramp up and down occurring during the guard periods as defined in GSM 05.05. A base transceiver station is not required to have a capability to ramp down and up between adjacent bursts, but is required to have a capability to ramp down and up for non‑used time‑slots, as defined in GSM 05.05. In any case where the amplitude of transmission is ramped up and down, then by applying an appropriate modulation bit stream interference to other RF channels can be minimized.

5.3 Physical channels and bursts

The description of a physical channel will be made in terms of timeslots and TDMA frames and not in terms of bursts. This is because there is not a one to one mapping between a particular physical channel, and the use of a particular burst.

5.4 Radio frequency channel sequence

The radio frequency channel sequence is determined by a function that, in a given cell, with a given set of general parameters, (see clause 5.6.2), with a given timeslot number (TN), a given mobile radio frequency channel allocation (MA) and a given mobile allocation index offset (MAIO), maps the TDMA frame number (FN) to a radio frequency channel.

In a given cell there is therefore, for a physical channel assigned to a particular mobile, a unique correspondence between radio frequency channel and TDMA frame number.

The detailed hopping generation algorithm is given in clause 6.2.

5.5 Timeslot and TDMA frame sequence

A given physical channel shall always use the same timeslot number in every TDMA frame. Therefore a timeslot sequence is defined by:

i) a timeslot number (TN); and

ii) a TDMA frame number sequence.

The detailed definitions of TDMA frame number sequences are given in clause 7.

The physical channels where the TDMA frame number sequence is 0,1. . FN_MAX (where FN_MAX is defined in clause 4.3.3) are called "basic physical channels".

5.6 Parameters for channel definition and assignment

5.6.1 General

This clause describes the set of parameters necessary to describe fully the mapping of any logical channel onto a physical channel. These parameters may be divided into general parameters, that are characteristic of a particular base transceiver station, and specific parameters, that are characteristic of a given physical channel.

5.6.2 General parameters

These are:

i) the set of radio frequency channels used in the cell (CA), together with the identification of the BCCH carrier.

ii) the TDMA frame number (FN), which can be derived from the reduced TDMA frame number (RFN) which is in the form T1, T2, T3′, see 3.3.2.

These parameters are broadcast (or derived from parameters broadcast) in the BCCH and SCH.

For COMPACT, these are:

i) the set of radio frequency channels used in the cell (CA), together with the identification of the COMPACT CPBCCH carrier (primary COMPACT carrier).

ii) the TDMA frame number (FN), which can be derived from the reduced TDMA frame number (RFN) which is in the form R1 and R2, see 3.3.2.

iii) the time group number (TG).

These parameters are broadcast (or derived from parameters broadcast) in the COMPACT CPBCCH and CSCH.

5.6.3 Specific parameters

These parameters define a particular physical channel in a base transceiver station. They are:

o) the training sequence Code (TSC);

i) the timeslot number (TN);

ii) the mobile radio frequency channel allocation (MA);

iii) the mobile allocation index offset (MAIO);

iv) the hopping sequence number (HSN);

v) the type of logical channel;

vi) the sub‑channel number (SCN).

The last two parameters allow the determination of the frame sequence.