Le Coded Phy Implementation; Le Coded Phy Packet Format - Infineon AIROC CYW20829 Bluetooth LE SoC Manual

r e s t r i c t e d
Achieving long range transmission using AIROC™ CYW20829
Bluetooth® LE SoC
Long range application
2.2

LE Coded PHY implementation

The LE Coded PHY can be used with two different coding schemes: S=2 and S=8. The Pattern Mapper converts
each bit from the convolutional FEC encoder into P symbols, where the value of P depends on the coding
scheme used. If S=2, there is no change (i.e. P=1). If S=8, each bit from the FEC encoder produces 4 output bits
(i.e. P=4) from the Pattern Mapper. The specifics are described in this section.
The choice of the coding scheme, S=2 or S=8, with the LE Coded PHY has two consequences. When two symbols
represent 1 bit, the PHY data rate is 500 Kbps; for S = 8 (where 8 represents 1 bit), the PHY data rate is 125 Kbps.
Due to the requirement for redundant data to support the FEC algorithm at the receiver end, it also impacts the
number of symbols, which must be transmitted and hence reduces the overall data rate. Specifically, one bit
which passed through both the FEC Encoder and the Pattern Mapper becomes 2 bits when S=2 or 8 bits when
S=8. The following table explains this.
Input
0
1
2.3

LE Coded PHY packet format

The packet format defined for the LE Coded PHY is shown in
Preamble
Figure 3 Packet format
Each packet consists of the Preamble, FEC block 1, and FEC block 2.
The Preamble is not coded.
•
The FEC block 1 consists of three fields: Access Address, Coding Indicator (CI), and TERM1. CI determines
•
which coding scheme is used for FEC block 2.
The FEC block 2 consists of three fields: PDU, CRC, and TERM2. These shall use either the S=2 or S=8 coding
•
scheme depending on the value of the CI.
The entire packet is transmitted with 1 Msym/s modulation..
Application note
Output with S=2
0
1
Access Address CI
Output with S=8
0011
1100
Figure 3.
TERM1 PDU, N bytes
6
Data rate
125 kb/s or 500 kb/s
125 kb/s or 500 kb/s
CRC TERM2
002-38518 Rev. **
2023-09-12