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Time Slicing Structure

Time Slicing Structure is defined in Annex M in ETSI EN 302 307-1. It is a technique within the DVB-S2 standard that allows receivers to select specific streams within a wideband signal at the physical layer, rather than needing to process the entire signal. The transmitter shall map the input services into streams (identified by a specific Time Slice Number, TSN). Such streams shall be transmitted in time slices (i.e. bursts) suitably spaced in time. A time-slicing burst (identified by a specific TSN) shall correspond to one PL-Frame. Time-slicing mode shall comply with the conventional DVB-S2/S2X, with the exception of the PL Signaling.

The PLHEADER shall be extended to two SLOTs of 90 symbols (180 symbols), composed of the following fields:

• SOF (26 symbols), identifying the Start of Frame; Same as DVB-S2 (no change)

• PLS code (154 symbols): 16 Information bits: 6-bit MODCOD, 2-bit TYPE (Frame length and pilot presence) and 8-bit TSN.

  • PLS (Physical Layer Signalling) code shall be a constraint length k=5, rate 1/5 convolutional code (77,16): 16 information bits => 80 bits after convolutional coding

        => puncture from 80 bits to 77 bits as follows:

• If (u₀, u₁, u₂, u₃, …, u₁₅) are the information bits, then each information bit shall generate 5 parity bits (p₀, p₁, p₂, …, p₄). Then, for information bits u₃, u₈, and u₁₃, the parity bit p₄ shall be punctured.

• "Tail biting" shall be used to complete the encoding process: depending on the input bits, the initial state shall be chosen so that the initial and final states are the same. The encoder initial state shall thus be set as:

  S₀=u₁₅; S₁=u₁₄; S₂=u₁₃; S₃=u₁₂

• Tail bits shall not be transmitted.

• Output bits (c₀, c₁, c₂, …, c₇₆) are repeated twice to produce the (154,16) codeword (c₀, c₀, c₁, c₁, c₂, c₂, …, c₇₆, c₇₆).

• The resulting 154 coded bits shall be scrambled with the following sequence:

1 0 1 1 1 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 1 0 1 0 1 0 0 0 1 0 1 1 1 0 1 1 1 0 1 0 1 1 1 0 0 1 0 0 1 1 1 0 1 1 0 0 0 0 1 0 1 1 0 0 0 1 1 1 1 1 1 0 1 1 0 1 0 1 1 0 0 1 1 0 1 1 0 1 1 1 0 0 0 0 1 1 1 0 0 0 1 1 0 1 0 1 0 0 1 1 1 1 1 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 0 0 0 0 1 1 1 1 0 1 1 1 1

• The PLHEADER, represented by the binary sequence (y1, y2, …, y180), shall be modulated into 180 Pi/2 BPSK symbols:

, , for

In N7623C Signal Studio, when the Time Slicing Structure is set to ON, you can set the Time Slicing Pattern (with TSL index) to decide the actual permutation of multiple PLFrames with different TSN. Corresponding TSN and MODCOD sequences will also be shown below. The PLFRAME length for each TSL will be calculated. For example, in the figure below, Time Slicing Sequence is [1, 2, 3, 4, 3, 1] by TSL index. Actual waveform generation and playback pattern by TSN: [0x01, 0x10, 0x20, 0x30, 0x20, 0x01]. If one specific receiver would only receive input stream with TSN 0x01, then it would decode the 1st and 6th PLFrames in the total 6 frames.

In time slicing mode, parameters VL-SNR, MODCOD, FEC, Pilot and Payload under "DVB-S2/S2X Settings" will be hidden, and they should be configured separately for each TSLs. The PLFRAME Length for each TSL will be computed accordingly. New TSL tree-node will be added with Add/Remove/Copy toolbar actions to support multiple TSLs. For Payload Data Source Type, only Test Pattern and Binary Pattern File are supported.