GB 15629.1102-2003Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications: Higher-speed physical layer extension in the 2.4 GHz band (English PDF)

6.1 Overview

This clause specifies the High Rate extension of the PHY for the Direct Sequence Spread Spectrum (DSSS) system (Clause 15 of GB 15629.11-2003), hereinafter known as the High Rate PHY for the 2.4GHz band designated for ISM applications.

This extension of the DSSS system builds on the data rate capabilities, as described in Clause 15 of GB 15629.11-2003, to provide 5.5Mbit/s and 11Mbit/s payload data rates in addition to the 1Mbit/s and 2Mbit/s rates. To provide the higher rates, 8-chip complementary code keying (CCK) is employed as the modulation scheme. The chipping rate is 11MHz, which is the same as the DSSS system described in Clause 15 of GB 15629.11-2003, thus providing the same occupied channel bandwidth. The basic new capability described in this clause is called High Rate Direct Sequence Spread Spectrum (HR/DSSS). The basic High Rate PHY uses the same PLCP preamble and header as the DSSS PHY, so both PHYs can co-exist in the same BSS and can use the rate switching mechanism as provided.

In addition to providing higher speed extensions to the DSSS system, a number of optional features allow the performance of the radio frequency LAN system to be improved as technology allows the implementation of these options to become cost effective.

An optional mode replacing the CCK modulation with packet binary convolutional coding (HR/DSSS/PBCC) is provided.

Another optional mode is provided that allows data throughput at the higher rates to be significantly increased by using a shorter PLCP preamble. This mode is called HR/DSSS/short, or HR/DSSS/PBCC/short. This Short Preamble mode can coexist with DSSS, HR/DSSS, or HR/DSSS/PBCC under limited circumstances, such as on different channels or with appropriate CCA mechanisms.

An optional capability for Channel Agility is also provided. This option allows an implementation to overcome some inherent difficulty with static channel assignments (a tone jammer), without burdening all implementations with the added cost of this capability. This option can also be used to implement GB 15629.1102-compliant systems that are interoperable with both FH and DS modulations. See Annex E for more details.

6.1 Overview

6.1 Overview

This clause specifies the High Rate extension of the PHY for the Direct Sequence Spread Spectrum (DSSS) system (Clause 15 of GB 15629.11-2003), hereinafter known as the High Rate PHY for the 2.4GHz band designated for ISM applications.

This extension of the DSSS system builds on the data rate capabilities, as described in Clause 15 of GB 15629.11-2003, to provide 5.5Mbit/s and 11Mbit/s payload data rates in addition to the 1Mbit/s and 2Mbit/s rates. To provide the higher rates, 8-chip complementary code keying (CCK) is employed as the modulation scheme. The chipping rate is 11MHz, which is the same as the DSSS system described in Clause 15 of GB 15629.11-2003, thus providing the same occupied channel bandwidth. The basic new capability described in this clause is called High Rate Direct Sequence Spread Spectrum (HR/DSSS). The basic High Rate PHY uses the same PLCP preamble and header as the DSSS PHY, so both PHYs can co-exist in the same BSS and can use the rate switching mechanism as provided.

In addition to providing higher speed extensions to the DSSS system, a number of optional features allow the performance of the radio frequency LAN system to be improved as technology allows the implementation of these options to become cost effective.

An optional mode replacing the CCK modulation with packet binary convolutional coding (HR/DSSS/PBCC) is provided.

Another optional mode is provided that allows data throughput at the higher rates to be significantly increased by using a shorter PLCP preamble. This mode is called HR/DSSS/short, or HR/DSSS/PBCC/short. This Short Preamble mode can coexist with DSSS, HR/DSSS, or HR/DSSS/PBCC under limited circumstances, such as on different channels or with appropriate CCA mechanisms.

An optional capability for Channel Agility is also provided. This option allows an implementation to overcome some inherent difficulty with static channel assignments (a tone jammer), without burdening all implementations with the added cost of this capability. This option can also be used to implement GB 15629.1102-compliant systems that are interoperable with both FH and DS modulations. See Annex E for more details.

6.1 Overview

6.1.1 Scope

This clause specifies the PHY entity for the HR/DSSS extension and the changes that have to be made to the base part to accommodate the High Rate PHY.

The High Rate PHY layer consists of the following two protocol functions:

a) A PHY convergence function, which adapts the capabilities of the PMD system to the PHY service. This function is supported by the PHY convergence procedure (PLCP), which defines a method for mapping the MAC sublayer protocol data units (MPDU) into a framing format suitable for sending and receiving user data and management information between two or more STAs using the associated PMD system. The PHY exchanges PHY protocol data units (PPDU) that contain PLCP service data units (PSDU). The MAC uses the PHY service, so each MPDU corresponds to a PSDU that is carried in a PPDU.

b) A PMD system, whose function defines the characteristics of, and method of transmitting and receiving data through, a wireless medium between two or more STAs, each using the High Rate PHY system.

6.1.1 Scope

6.1.1 Scope

This clause specifies the PHY entity for the HR/DSSS extension and the changes that have to be made to the base part to accommodate the High Rate PHY.

The High Rate PHY layer consists of the following two protocol functions:

a) A PHY convergence function, which adapts the capabilities of the PMD system to the PHY service. This function is supported by the PHY convergence procedure (PLCP), which defines a method for mapping the MAC sublayer protocol data units (MPDU) into a framing format suitable for sending and receiving user data and management information between two or more STAs using the associated PMD system. The PHY exchanges PHY protocol data units (PPDU) that contain PLCP service data units (PSDU). The MAC uses the PHY service, so each MPDU corresponds to a PSDU that is carried in a PPDU.

b) A PMD system, whose function defines the characteristics of, and method of transmitting and receiving data through, a wireless medium between two or more STAs, each using the High Rate PHY system.

6.1.1 Scope

6.1.2 High Rate PHY functions

The 2.4GHz High Rate PHY reference model is depicted in Figure 11. The High Rate PHY contains three functional entities: the PHY convergence function, the PMD function, and the layer management function. Each of these functions is described in detail in 6.1.2.1, 6.1.2.2, and 6.1.2.3. For the purposes of MAC and MAC management, when Channel Agility is both present and enabled (see 6.3.2 and Annex B), the High Rate PHY shall be interpreted to be both a High Rate and a frequency-hopping PHY.

The High Rate PHY service shall be provided to the MAC through the PHY service primitives described in Clause 12 of GB 15629.11-2003.

6.1.2 High Rate PHY functions

6.1.2 High Rate PHY functions

The 2.4GHz High Rate PHY reference model is depicted in Figure 11. The High Rate PHY contains three functional entities: the PHY convergence function, the PMD function, and the layer management function. Each of these functions is described in detail in 6.1.2.1, 6.1.2.2, and 6.1.2.3. For the purposes of MAC and MAC management, when Channel Agility is both present and enabled (see 6.3.2 and Annex B), the High Rate PHY shall be interpreted to be both a High Rate and a frequency-hopping PHY.

The High Rate PHY service shall be provided to the MAC through the PHY service primitives described in Clause 12 of GB 15629.11-2003.

6.1.2 High Rate PHY functions

6.1.2.1 PLCP sublayer

To allow the MAC to operate with minimum dependence on the PMD sublayer, a PLCP sublayer is defined. This function simplifies the PHY service interface to the MAC services.

6.1.2.1 PLCP sublayer

To allow the MAC to operate with minimum dependence on the PMD sublayer, a PLCP sublayer is defined. This function simplifies the PHY service interface to the MAC services.

6.1.2.2 PMD sublayer

The PMD sublayer provides a way and method of transmitting and receiving data through a WM between two or more STAs, each using the High Rate system.

6.1.2.2 PMD sublayer

The PMD sublayer provides a way and method of transmitting and receiving data through a WM between two or more STAs, each using the High Rate system.

6.1.2.3 PHY management entity (PLME)

The PLME performs management of the local PHY functions in conjunction with the MAC management entity (MLME).

6.1.2.3 PHY management entity (PLME)

The PLME performs management of the local PHY functions in conjunction with the MAC management entity (MLME).

6.1.3 Service specification method and notation

The models represented by figures and state diagrams are intended to be illustrations of the functions provided. It is important to distinguish between a model and a real implementation. The models are optimized for simplicity and clarity of presentation; the actual method of implementation is left to the discretion of the High Rate PHY compliant developer.

The service of a layer or sublayer is a set of capabilities that it offers to a user in the next higher layer (or sublayer). Abstract services are specified here by describing the service primitives and parameters that characterize each service. This definition is independent of any particular implementation.

6.1.3 Service specification method and notation

6.1.3 Service specification method and notation

The models represented by figures and state diagrams are intended to be illustrations of the functions provided. It is important to distinguish between a model and a real implementation. The models are optimized for simplicity and clarity of presentation; the actual method of implementation is left to the discretion of the High Rate PHY compliant developer.

The service of a layer or sublayer is a set of capabilities that it offers to a user in the next higher layer (or sublayer). Abstract services are specified here by describing the service primitives and parameters that characterize each service. This definition is independent of any particular implementation.

6.1.3 Service specification method and notation

6.2 High Rate PLCP Sublayer

6.2 High Rate PLCP Sublayer

6.2 High Rate PLCP Sublayer

6.2 High Rate PLCP Sublayer

6.2.1 Overview

This subclause provides a convergence procedure for the 2, 5.5, and 11Mbit/s specification, in which PSDUs are converted to and from PPDUs. During transmission, the PSDU shall be appended to a PLCP preamble and header to create the PPDU. Two different preambles and headers are defined: the mandatory supported Long Preamble and header, which interoperates with the current 1Mbit/s and 2Mbit/s DSSS specification (as described in Clause 15 of GB 15629.11-2003), and an optional Short Preamble and header. At the receiver, the PLCP preamble and header are processed to aid in demodulation and delivery of the PSDU.

The optional Short Preamble and header are intended for applications where maximum throughput is desired and interoperability with legacy and non-short-preamble capable equipment is not a consideration. That is, they are expected to be used only in networks of like equipment, which can all handle the optional mode.

6.2.1 Overview

6.2.1 Overview

This subclause provides a convergence procedure for the 2, 5.5, and 11Mbit/s specification, in which PSDUs are converted to and from PPDUs. During transmission, the PSDU shall be appended to a PLCP preamble and header to create the PPDU. Two different preambles and headers are defined: the mandatory supported Long Preamble and header, which interoperates with the current 1Mbit/s and 2Mbit/s DSSS specification (as described in Clause 15 of GB 15629.11-2003), and an optional Short Preamble and header. At the receiver, the PLCP preamble and header are processed to aid in demodulation and delivery of the PSDU.

The optional Short Preamble and header are intended for applications where maximum throughput is desired and interoperability with legacy and non-short-preamble capable equipment is not a consideration. That is, they are expected to be used only in networks of like equipment, which can all handle the optional mode.

Contents of GB 15629.1102-2003 Foreword i

6.2.1 Overview

6.2.2 PPDU format

6.2.2 PPDU format

6.2.3 PLCP PPDU field definitions

6.2.3 PLCP PPDU field definitions

6.2.4 PLCP/High Rate PHY data scrambler and descrambler

6.2.4 PLCP/High Rate PHY data scrambler and descrambler

6.2.5 PLCP transmit procedure

6.2.5 PLCP transmit procedure

6.2.6 PLCP receive procedure

6.2.6 PLCP receive procedure

6.3 High Rate PLME

6.3 High Rate PLME

6.3.1 PLME_SAP sublayer management primitives

6.3.1 PLME_SAP sublayer management primitives

6.3.2 High Rate PHY MIB

6.3.2 High Rate PHY MIB

6.3.3 DS PHY characteristics

6.3.3 DS PHY characteristics

6.3.4 High rate TXTIME calculation

6.3.4 High rate TXTIME calculation

6.3.5 Vector descriptions

6.3.5 Vector descriptions

6.4 High Rate PMD Sublayer

6.4 High Rate PMD Sublayer

6.4.1 Scope and field of application

6.4.1 Scope and field of application

6.4.2 Overview of service

6.4.2 Overview of service

6.4.3 Overview of interactions

6.4.3 Overview of interactions

6.4.4 Basic service and options

6.4.4 Basic service and options

6.4.5 PMD_SAP detailed service specification

6.4.5 PMD_SAP detailed service specification

6.4.6 PMD operating specifications (general)

6.4.6 PMD operating specifications (general)

6.4.7 PMD transmit specifications

6.4.7 PMD transmit specifications

6.4.8 PMD receiver specifications

Annex A (Normative) Protocol Implementation Conformance Statement (PICS) Proforma

A.1 IUT Configuration

A.2 High Rate, Direct Sequence PHY Functions

Annex B (Normative) Formal Description of MAC Operation

Annex C (Normative) Changes to GB 15629.11 C.1 Frame Format

C.1.1 Capability Information field

C.1.2 Status code field C.2 Layer Management

C.2.1 PLME_DSSSTESTMODE

Annex D (Normative) ASN.1 Encoding of the MAC and PHY MIB

Annex E (Informative) High Rate PHY/FH Interoperability

E.1 Additional CCA Recommendations

Figure 1 Long PLCP PPDU Format

Figure 2 Short PLCP PPDU Format

Figure 3 CCITT CRC-16 Implementation

Figure 4 Example of CRC Calculation

Figure 5 Data Scrambler

Figure 6 Data Descrambler

Figure 7 PLCP Transmit Procedure

6.4.8 PMD receiver specifications

Annex A (Normative) Protocol Implementation Conformance Statement (PICS) Proforma

A.1 IUT Configuration

A.2 High Rate, Direct Sequence PHY Functions

Annex B (Normative) Formal Description of MAC Operation

Annex C (Normative) Changes to GB 15629.11 C.1 Frame Format

C.1.1 Capability Information field

C.1.2 Status code field C.2 Layer Management

C.2.1 PLME_DSSSTESTMODE

Annex D (Normative) ASN.1 Encoding of the MAC and PHY MIB

Annex E (Informative) High Rate PHY/FH Interoperability

E.1 Additional CCA Recommendations

Figure 1 Long PLCP PPDU Format

Figure 2 Short PLCP PPDU Format

Figure 3 CCITT CRC-16 Implementation

Figure 4 Example of CRC Calculation

Figure 5 Data Scrambler

Figure 6 Data Descrambler

Figure 7 PLCP Transmit Procedure