Packet Format

Base Packet Format

Section	Field Name	Size	Purpose
Synchronization	Preamble	4 bytes	Composed of zeros to help the receiver synchronize with the signal.
Synchronization	Start-of-Packet Delimiter	1 byte	A specific value (0xA7) that signals the actual beginning of the packet.
PHY Header	PHR (PHY Header)	1 byte (8 bits)	Contains a single field indicating the length of the payload (0–127).
Payload	PSDU (PHY Service Data Unit)	$\le 127$ bytes	The actual data content being transmitted.
Inside the payload, we have the [[#mac-frame	Mac Frame]].

Mac Frame

Section	Field Name	Size (Octets)
MAC Header	Frame control	2
MAC Header	Sequence number	1
MAC Header (Addressing)	Destination PAN identifier	0 or 2
MAC Header (Addressing)	Destination address	0, 2, or 8
MAC Header (Addressing)	Source PAN identifier	0 or 2
MAC Header (Addressing)	Source address	0, 2, or 8
MAC Payload	Frame payload	Variable
MAC Footer	Frame check sequence	2

• The sequence number is an 8-bit monotonically incrasing number.
• The frame check sequence is a 16-bit CRC.

There are a couple different frame types:

• Beacon
• Data
• MAC Command
• Acknowledgement

Throughput

If we assume the best possible case for data transmission,

• 122 Bytes per packet, 250 kbps $\to$ 3.904 ms
• inter-frame spacing of 40 symbols, 62.5 kBaud $\to$ 0.640 ms
• So, $$\frac{122\text{ bytes}}{4.544\text{ ms}}=214\text{ kbps}$$

Compared to BLE Advertisements at 9.92 kbps, this is better. But compared to BLE connections at 520 kbps, it is worse.