IEEE Std 802.15.8-2017 pdf free download – IEEE Standard for Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Peer Aware Communications (PAC).
4. Format conventions
4.1 General
Throughout this standard, unless otherwise stated, data structures exposed in interfaces (SAPs) through primitives are represented using the serial bit convention and format specified in this clause. However, vendors may implement such interfaces in other forms, e.g., 4- or 8-bit parallel. Within a PHY frame using the serial bit convention, the size of a MAC frame shall be less than the maximum PSDU size supported by the PHY in use. A PHY frame using the serial bit convention represents the over-the-air messages in this standard.
4.2 Fields
4.2.1 Overview
The general format of a data structure is shown in Figure 1. Each field is represented by a column with a row indicating the size of the field in either octets or bits; and another row below indicating the name of the field with the convention to begin every word with a capital letter. This data structure is recursive such that a field may contain a data structure, which is in turn composed of fields.
The form “Octets: n” means the field is n octets long. The form “Bits: n” or “Bits: m─n” means bit number n or bits m to n of an octet. If a field uses the “Bits:” form, a complete octet shall be described as illustrated in Figure 1.
If a field length appears without either Octets or Bits, then the preceding units apply as illustrated in Figure 1. The form “Octets: n/m/l” means the field can be n, m or l octets long. The form “Variable” means the size in octets of the field changes and an exact value cannot be written. In that case, an extra field may be added to indicate the length of the “Variable” size field for a particular MAC frame as illustrated in Figure 1. In this example, the size in octets range from 0 to 255. When the number of fields is such they cannot be fitted in one row, additional rows are used as illustrated in Figure 1.
The order of representation is strict from the upper row to the lower row with the leftmost field occurring before the next field to its right, and subsequently until the lower rightmost field is reached and occurring last.
4.2.2 Numbers
Numbers are represented in decimal (nnn) or binary (0bnnn) notation with the number of digits indicated, or hexadecimal (0xmm) notation. For example, 0b001 is a 3 digit binary number of value 1 and 0x01 is the hexadecimal number of value 1. Numbers specified in fields, tables, and parameters of service primitives can be integers or single-precision floating-point numbers. Numbers specified as “b-bit integers” denote b- bit unsigned integers, where b is a positive integer number. For simplicity, 8-bit unsigned integers are specified as “Integers”. “Signed integers” are 32-bit signed integers with two’s complement for negative numbers. Single-precision floating-point numbers are specified as “Float”.
4.2.3 Strings
The term string is used when the field’s content is not interpreted as a number specified in 4.2.2, but rather mapped onto another format. For example, the octet 0b01000001 represents the letter “A” in the extended ASCII format, or cryptographic keys.IEEE Std 802.15.8 pdf download.