1.	Direct Sequence Spread Spectrum Physical Layer Specification for the 2.4 GHz ISM Band

1.1		Introduction
This section describes the physical layer for the Direct Sequence Spread Spectrum (DSSS) system.  The Radio Frequency LAN system is initially aimed for the 2.4 GHz ISM band as provided in the USA according to Document FCC 15.247 and in Europe by ETS 300-328.  Other countries have similar regulations.
The DSSS system provides a wireless LAN with both a 1 Mb/s and a 2 Mb/s data payload communication capability.  According to the FCC regulations,  the DSSS system shall provide a processing gain of at least 10 dB.  This shall be accomplished by chipping the baseband signal at 11 MHz with an 11-chip PN code.  The DSSS system uses baseband modulations of Differential Binary Phase Shift Keying (DBPSK) and Differential Quadrature Phase Shift Keying (DQPSK) to provide the 1 and 2 Mb/s data rates, respectively. 
1.1.1		Scope
This section describes the physical layer services provided to the 802.11 wireless LAN MAC by the 2.4 GHz Direct Sequence Spread Spectrum system.  The DSSS PHY layer consists of two protocol functions:
a)	A physical layer convergence function which adapts the capabilities of the physical  medium dependent system into the Physical Layer service.  This function shall be supported by the Physical Layer Convergence Procedure (PLCP) which defines a method of mapping the 802.11 MAC layer Protocol Data Units (MPDU) into a framing format suitable for sending and receiving user data and management information between two or more stations using the associated physical medium dependent system.
b)	A Physical Medium Dependent (PMD) system whose function defines the characteristics  and method of transmitting and receiving data via wireless media between two or more nodes. 

Each physical medium dependent sublayer for the DSSS PMD may require the definition of a unique PLCP.  If the PMD sublayer already provides the defined Physical Layer services, the physical layer convergence function might be null.
1.1.2		DSSS Physical Layer Functions
The 2.4 GHz DSSS PHY architecture is depicted in the reference model shown in Error! Reference source not found..  The DSSS physical layer contains three functional entities:  the physical medium dependent function, the physical layer convergence function, and the layer management function.  Each of these functions is described in detail in the following subsections.
The DSSS Physical Layer service shall be provided to the Media Access Control through the physical layer service primitives described in clause Error! Reference source not found.. 
1.1.2.1		Physical Layer Convergence Procedure Sublayer
In order to allow the 802.11 MAC to operate with minimum dependence on the PMD sublayer, a physical layer convergence sublayer is defined.  This function simplifies the physical layer service interface to the 802.11 MAC services.
1.1.2.2		Physical Medium Dependent Sublayer
The physical medium dependent sublayer provides a means to send and receive data between two or more stations.  This section is concerned with the 2.4 GHz ISM bands using Direct Sequence modulation.
1.1.2.3		Physical Layer Management Entity (LME)
The Physical LME performs management of the local Physical Layer Functions in conjunction with the MAC Management entity.
1.1.3		Acronyms
CCA		Clear Channel Assessment
CRC		Cyclic Redundancy Check
DBPSK		Differential Binary Phase Shift Key
DQPSK		Differential Quadrature Phase Shift Key
DSSS		Direct Sequence Spread Spectrum
ED		Energy Detection
FCS		Frame Check Sequence
FER		Frame Error Rate
LME		Layer Management  Entity
LSB		Least Significant Bit
MAC		Media Access Control
MIB		Management Information Base
MPDU		MAC Protocol Data Unit
MSB		Most Significant Bit
PHY_SAP	Physical Layer Service Access Point
PLCP		Physical Layer Convergence Procedure
PLME		PHY Layer Management Entity
PMD		Physical Medium Dependent
PMD_SAP	Physical Medium Dependent Service Access Point
PN		Pseudo Noise (PN code sequence)
PPDU		PHY Protocol Data Unit
RSSI		Received Signal Strength Indication
SAP		Service Access Point
SFD		Start Frame Delimiter
SQ		Signal Quality (PN code correlation strength)
TXE		Transmit Enable

1.1.4		Service Specification Method and Notation
The models represented by figures and state diagrams are intended to be illustrations of 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 802.11 DSSS 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.
1.2		DSSS Physical Layer Convergence Procedure Sublayer
1.2.1		Introduction
This section provides a convergence procedure in which MPDUs  are converted to and from PPDUs. During transmission, the MPDU shall be prepended with a PLCP preamble and header to create the PPDU.  At the receiver, the PLCP preamble and header are processed to aid in demodulation and delivery of the MPDU. 
1.2.2		Physical Layer Convergence Procedure Frame Format
Figure 1176 shows the format for the PPDU including the DSSS PLCP preamble, the DSSS PLCP header and the MPDU.  The PLCP preamble contains the following fields:  synchronization (SYNC) and  Start Frame Delimiter (SFD).  The PLCP header contains the following fields:  802.11 signaling (SIGNAL), 802.11 service(SERVICE), length(LENGTH), and CCITT CRC-16.  Each of these  fields are described in detail in clause 1.2.3.

Figure 1, PLCP Frame Format
1.2.3		PLCP Field Definitions
The entire PLCP preamble and header shall be transmitted using the 1 Mb/s DBPSK  modulation described in clause 1.4.7.  All transmitted bits shall be scrambled using the feedthrough scrambler described in clause 1.2.4.
1.2.3.1		PLCP Synchronization (SYNC)
The synchronization field shall consist of 128 bits of scrambled 1 bits.  This field shall be provided so that the receiver can perform the necessary operations for synchronization.
1.2.3.2		PLCP Start Frame Delimiter (SFD)
The Start Frame Delimiter shall be provided to indicate the start of PHY dependent parameters within the PLCP preamble.  The SFD shall be a 16 bit field,  hF3A0 (MSB to LSB).  The LSB shall be transmitted first in time. 
1.2.3.3		PLCP 802.11 Signal Field (SIGNAL)
The 8 bit 802.11 signal field indicates to the PHY the modulation which shall be used for transmission (and reception) of the MPDU.  The data rate shall be equal to the Signal Field value multiplied by 100Kb/s.  The DSSS PHY currently supports two mandatory modulation services given by the following 8 bit words, where the LSB shall be transmitted first in time:
a)	h0A (MSB to LSB) for 1 Mb/s DBPSK  
b)	h14 (MSB to LSB) for 2 Mb/s DQPSK 

The DSSS PHY rate change capability is described in clause 1.2.5.  This field shall be protected by the CCITT CRC-16 frame check sequence described in clause 1.2.3.6.
1.2.3.4		PLCP 802.11 Service Field (SERVICE)
The 8 bit 802.11 service field shall be reserved for future use.  The value of h00 signifies 802.11 device compliance.  The LSB shall be transmitted first in time.  This field shall be protected by the CCITT CRC-16 frame check sequence described in clause 1.2.3.6.
1.2.3.5		PLCP Length Field (LENGTH)
The PLCP length field shall be an unsigned 16 bit integer which indicates the number of octets (4 to 216 as defined by aMPDU_Max_Lngth) to be transmitted in the MPDU.  The transmitted value shall be provided by the LENGTH parameter in the TXVECTOR issued with the PHY_TXSTART.request primitive described in clause Error! Reference source not found..  The LSB (least significant bit) shall be transmitted first in time.  This field shall be protected by the CCITT CRC-16 frame check sequence described in clause 1.2.3.6.
1.2.3.6		PLCP CRC Field (CCITT CRC-16)
The 802.11 SIGNAL, 802.11 SERVICE, and LENGTH fields shall be protected with a CCITT CRC-16 FCS (frame check sequence).  The CCITT CRC-16 FCS shall be the ones complement of the remainder generated by the modulo 2 division of the protected PLCP fields by the polynomial:
x16 +  x12   +  x5 + 1
The protected bits shall be processed in transmit order.  All FCS calculations shall be made prior to data scrambling. 
As an example, the SIGNAL, SERVICE, and LENGTH fields for a DBPSK signal with a packet length of 192 bytes would be given by the following:
0101 0000 0000 0000 0000 0011 0000 0000 (left most bit transmitted first in time)
The ones complement FCS for these protected PLCP preamble bits would be the following:
0101 1011 0101 0111 (left most bit transmitted first in time)
Figure 2277 depicts this example.

Figure 2, CCITT CRC-16 Implementation

An illustrative example of the CCITT CRC-16 FCS using the above information follows in Figure 3378.

	           Data	        CRC Registers
		          MSB                             LSB
			
		 	1111111111111111	; Initialize Preset to 1’s
		0	1110111111011111
		1	1101111110111110
		0	1010111101011101
		1	0101111010111010
		0	1011110101110100
		0	0110101011001001
		0	1101010110010010
		0	1011101100000101
		0	0110011000101011
		0	1100110001010110
		0	1000100010001101
		0	0000000100111011
		0	0000001001110110
		0	0000010011101100
		0	0000100111011000
		0	0001001110110000
		0	0010011101100000
		0	0100111011000000
		0	1001110110000000
		0	0010101100100001
		0	0101011001000010
		0	1010110010000100
		1	0101100100001000
		1	1010001000110001
		0	0101010001000011
		0	1010100010000110
		0	0100000100101101
		0	1000001001011010
		0	0001010010010101
		0	0010100100101010
		0	0101001001010100
		0	1010010010101000
			0101101101010111	; 1’s Complement, Result = CRC FCS Parity

Figure 3, Example CRC Calculation
1.2.4		PLCP / DSSS PHY Data Scrambler and Descrambler
The polynomial G(z) = z-7 +  z-4 + 1 shall be used to scramble ALL bits transmitted by the DSSS PHY.  The feedthrough configuration of the scrambler shall be self synchronizing requiring no prior knowledge of the transmitter initialization of the scrambler shall be required for receive processing.  Figure 4479 and Figure 5580 show typical implementations of the data scrambler and descrambler.  Other implementations are possible.
The scrambler should be initialized to any state except all ones when transmitting.

Figure 4, Data Scrambler

Figure 5, Data Descrambler
1.2.5		PLCP Data Modulation and Modulation Rate Change
The PLCP preamble shall be transmitted using the 1 Mb/s DBPSK modulation.  The 802.11 SIGNAL field shall indicate the modulation which shall be used to transmit the MPDU.  The transmitter and receiver shall initiate the modulation indicated by the 802.11SIGNAL field starting with the first symbol (1bit for DBPSK or 2 bits for DQPSK) of the MPDU.  The MPDU transmission rate shall be set by the SIGNAL parameter in the TXVECTOR issued with the PHY_TXSTART.request primitive described in clause 9.
1.2.6		PLCP Transmit Procedure
The PLCP transmit procedure is shown in Figure 6681.
In order to transmit data, PHY_TXSTART.request shall be enabled so that the PHY entity shall be in the transmit state.  Further, the PHY shall be set to operate at the appropriate CHNL_ID through Station Management via the PLME.  Other transmit parameters such as RATE, TX antenna, and TX power are set via the PHY-SAP with the TXSTART.request(TXVECTOR) as described in clause 9.
Based on the status of CCA indicated by PHY_CCA.indicate, the MAC will assess that the channel is clear.  A clear channel shall be indicated by PHY_CCA.indicate(IDLE).  If the channel is clear, transmission of the MPDU shall be initiated by issuing the PHY_TXSTART.request (TXVECTOR) primitive.  The TXVECTOR elements for the PHY_TXSTART.request are the PLCP header parameters SIGNAL, SERVICE and LENGTH and the PMD parameters of TX_ANTENNA, and TXPWR_LEVEL.
The PLCP shall issue PMD_ANTSEL, PMD_RATE, and PMD_TXPWRLVL primitives to configure the PHY.  The PLCP shall then issue a PMD_TXSTART.request and the PHY entity shall immediately initiate data scrambling and transmission of the PLCP preamble based on the parameters passed in the PHY_TXSTART.request primitive.  The time required  for TX power on ramp described in clause 1.4.7.7 shall be included in the PLCP synchronization field.  Once the PLCP preamble transmission is complete, data  shall be exchanged  between the MAC and the PHY by a series of PHY_DATA.request(DATA) primitives issued by the MAC.  The modulation rate change, if any, shall be initiated with the first data symbol of the MPDU as described in clause 1.2.5.  The PHY proceeds with MPDU transmission through a series of data octet transfers from the MAC.  At the PMD layer, the data octets are sent in LSB to MSB order and presented to the PHY layer through PMD_DATA.request primitives.  Transmission can be prematurely terminated by the MAC through the primitive PHY_TXEND.request.  PHY_TXSTART shall be disabled by the issuance of the PHY_TXEND.request.  Normal termination occurs after the transmission of the final bit of the last MPDU octet according to the number supplied in the DSSS PHY preamble LENGTH field.  The packet transmission shall be completed and the PHY entity shall enter the receive state (i.e. PHY_TXSTART shall be disabled).  It is recommended that chipping continue during power down.

Figure 6, PLCP Transmit Procedure
A typical state machine implementation of the PLCP transmit procedure is provided in Figure 7782. 

Figure 7, PLCP Transmit State Machine
1.2.7		PLCP Receive Procedure
The PLCP receive procedure is shown in Figure 8883.
In order to receive data, PHY_TXSTART.request shall be disabled so that the PHY entity is in the receive state.  Further, through Station Management via the PLME, the PHY is set to the appropriate CHNL_ID and the CCA method is chosen.  Other receive parameters such as RSSI, SQ (signal quality), and indicated RATE may be accessed via the PHY-SAP.
Upon receiving the transmitted energy, according to the selected CCA mode, the PMD_ED shall be enabled (according to clause 1.4.8.4) as the RSSI strength reaches the ED_THRESHOLD and/or PMD_CS shall be enabled after code lock is established.   These conditions are used to indicate activity to the MAC via PHY_CCA.indicate according to clause 1.4.8.4.  PHY_CCA.indicate(BUSY) shall be issued for energy detection or code lock prior to correct reception of the PLCP frame.  The PMD primitives PMD_SQ and PMD_RSSI are issued to update the RSSI and SQ parameters reported to the MAC. 
After PHY_CCA.indicate is issued, the PHY entity shall begin searching for the SFD field.  Once the SFD field is detected, CCITT CRC-16 processing shall be initiated and the PLCP 802.11 SIGNAL, 802.11 SERVICE, and LENGTH fields are received.  The CCITT CRC-16 FCS shall be processed.  If the CCITT CRC-16 FCS check fails, the PHY receiver shall return to the RX Idle state as depicted in Figure 9984.  Should the status of CCA return to the IDLE state during reception prior to completion of the full PLCP processing, the PHY receiver shall return to the RX Idle state.
If the PLCP header reception is successful (and the SIGNAL field is completely recognizable and supported), a PHY_RXSTART.indicate(RXVECTOR) shall be issued. The RXVECTOR associated with this primitive includes the SIGNAL field, the SERVICE field, the LENGTH field, the antenna used for receive,  PHY_RSSI, and PHY_SQ.
The received MPDU bits are assembled into octets and presented to the MAC using  a series of PHY_DATA.indicate(DATA) primitive exchanges.  The rate change indicated in the 802.11 SIGNAL field shall be initiated with the first symbol of the MPDU as described in clause 1.2.5. The PHY proceeds with MPDU reception.  After the reception of the final bit of the last MPDU octet indicated by the PLCP preamble LENGTH field, the receiver shall be returned to the RX Idle state as shown in Figure 9984.   A PHY_RXEND.indicate(No_Error) primitive shall be issued.   A PHY_CCA.indicate(IDLE) primitive shall be issued following a change in PHY_CS and/or PHY_ED according to the selected CCA method.
In the event that a change in PHY_CS or PHY_ED would cause the status of CCA to return to the IDLE state before the complete reception of the MPDU as indicated by the PLCP LENGTH field, the error condition PHY_RXEND.indicate(carrier_lost) shall be reported to the MAC.  The DSSS PHY shall ensure that the CCA shall indicate a busy medium for the intended duration of the transmitted packet.

Figure 8, PLCP Receive Procedure
A typical state machine implementation of the PLCP receive procedure is provided in Figure 9984. 

Figure 9, PLCP Receive State Machine
1.3		DSSS Physical Layer Management Entity (PLME)

1.3.1		PLME_SAP Sublayer Management primitives
Table 1 lists the primitives which may be sent between the PHY sublayer entities and intra layer of higher Layer Management Entities (LME).
Primitive	Request	Indicate	Confirm	Response	
PLME_CCA_MODE	X				
PLME_CHNL_ID	X				
PLME_DIVERSITY	X				
PLME_DOZE	X				
					
PLME_RESET	X				
Table 1, PLME_SAP Sublayer Management Primitives
1.3.2	 PLME_SAP Management Service Primitive Parameters
Table 2252 shows the parameters used by the PLME_SAP primitives.
Parameter	Associated Primitive	Value	
CCA_MODE	PLME_CCA_MODE.request	ED_Only, CS_Only, ED+CS	
ED_THRESHOLD	PLME_CCA_MODE.request	ED Threshold if required for CCA operation	
CHNL_ID	PLME_CHNL_ID.request	1-11 for FCC, 3-11 for ETSI, 12 for Japan	
ANT_LIST	PLME_DIVERSITY.request	list of valid antennas to search	
DIV_MODE	PLME_DIVERSITY.request	Enabled or Disabled	
Table 2, PLME_SAP Primitive Parameters
1.3.3	 PLME_ SAP Detailed Service Specification
1.3.3.1	 PLME_RESET.request
	Function
This primitive shall be a request by the LME to reset the PHY.  The PHY shall be always reset to the receive state to avoid accidental data transmission.
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_RESET.request
There are no parameters associated with this primitive.
	When Generated
This primitive shall be generated at any time to reset the PHY.
	Effect of Receipt
Receipt of this primitive by the PHY sublayer shall cause the PHY entity to reset both the transmit and the receive state machines and place the PHY into the receive state. 

1.3.3.2	 PLME_CCA_MODE.request
	Function
This primitive shall be a request by the LME to establish a particular CCA mode operation for the PHY.
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_CCA_MODE.request(CCA_MODE, ED_THRESHOLD)
CCA_MODE shall indicate one of three CCA operational modes of energy detect only, carrier sense only, or a combination of energy detect and carrier sense.
	When Generated
This primitive shall be generated at any time to change the CCA mode used by the PHY.
	Effect of Receipt
Receipt of this primitive by the PHY sublayer shall cause the PHY entity to use the specified CCA_MODE with the ED Threshold set as appropriate for the mode of operation.

1.3.3.3	 PLME_CHNL_ID.request
	Function
This primitive shall be a request by the LME to set the operational frequency of  the PHY.
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_CHNL_ID.request(CHNL_ID)
The CHNL_ID parameter shall be 1-11 for FCC, 3-11 for ETSI, or 12 for Japan.
	When Generated
This primitive shall be generated at any time to alter the frequency of operation of  the PHY.
	Effect of Receipt
Receipt of this primitive by the PHY sublayer shall cause the PHY entity to change the frequency of operation according to the CHNL_ID parameter.

1.3.3.4	 PLME_DOZE.request
	Function
This primitive shall be a request by the LME to place the PHY into the DOZE state.
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_DOZE.request
There are no parameters associated with this primitive.
	When Generated
This primitive shall be generated at any time to place the PHY into the DOZE state.
	Effect of Receipt
Receipt of this primitive by the PHY sublayer shall cause the PHY entity to place itself into the DOZE state.

1.3.3.5	 PLME_DIVERSITY.request
	Function
This primitive shall be a request by the LME to enable or disable the PHY from using antenna diversity.
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_DIVERSITY.request(DIV_MODE,ANT_LIST)
DIV_MODE shall cause the diversity function to be enabled or disabled.  ANT_LIST shall contain the antenna numbers which are valid to search.
	When Generated
This primitive shall be generated at any time to change the operating mode of antenna diversity.
	Effect of Receipt
Receipt of this primitive by the PHY sublayer shall cause the PHY entity to change the operating state of the antenna diversity function according to the parameters DIV_MODE and ANT_LIST.

1.3.4	 DSSS Physical Layer Management Information Base
All DSSS Physical Layer Management Information Base attributes are defined in clause 10 with specific values defined in Table 3353.
Managed Object	Default Value / Range	Operational Semantics	
agPhyOperation_grp			
aPHY_Type 	DSSS-2.4 (02)	Static	
aTemp_Type	type1, type2
implementation dependent	Static	
aReg_Domains_Suprt	implementation dependent	Static	
aCurrent_Reg_Domain	implementation dependent	Static	
aSlot_Time	20 usec	Static	
aCCA_Asmnt_Time	 15 usec	Static	
aRxTx_Turnaround_Time	 5 usec	Static	
aTx_PLCP_Delay	implementation dependent	Static	
aRxTx_Switch_Time	 5 usec	Static	
aTxRamp_On_Time	implementation dependent	Static	
aTx_RF_Delay	implementation dependent	Static	
aSIFS_Time	10 usec	Static	
aRx_RF_Delay	implementation dependent	Static	
aRx_PLCP_Delay	implementation dependent	Static	
aMAC_prc_Delay	not applicable	n/a	
aTxRamp_Off_Time	implementation dependent	Static	
aPreamble_Length	144 bits	Static	
aPLCP_Header_Length	48 bits	Static	
			
agPhyRate_grp			
aSuprt_Data_Rates	01,02	Static	
aMPDU_Max_Lngth	4  x  (2^16 - 1)	Static	
			
agPhyAntenna_grp			
aSuprt_Tx_Antennas	implementation dependent	Static	
aCurrent_Tx_Antenna	implementation dependent	Dynamic	
aSuprt_Rx_Antennas	implementation dependent	Static	
aDiversity_Suprt	implementation dependent	Static	
aDiversity_Slct_Rx	implementation dependent	Dynamic	
			
agPhyTxPwr_grp			
aNbr_Suprtd_Pwr_Lvls	implementation dependent	Static	
aTx_Pwr_Lvl1	implementation dependent	Static	
aTx_Pwr_Lvl2	implementation dependent	Static	
aTx_Pwr_Lvl3	implementation dependent	Static	
aTx_Pwr_Lvl4	implementation dependent	Static	
aTx_Pwr_Lvl5	implementation dependent	Static	
aTx_Pwr_Lvl6	implementation dependent	Static	
aTx_Pwr_Lvl7	implementation dependent	Static	
aTx_Pwr_Lvl8	implementation dependent	Static	
aCurrent_Tx_PwrLvl	implementation dependent	Dynamic	
			
agPhyStatus_grp			
aSynthesizer_Locked	implementation dependent 	Dynamic	
			
agPhyDSSS_grp			
aCurrent_Channel	implementation dependent	Dynamic	
aCCA_Mode_Suprt	implementation dependent	Static	
aCurrent_CCA_Mode	implementation dependent	Dynamic	
aED_Threshold	implementation dependent	Dynamic	
			
agPowerSaving_grp			
			
aDoze_Turnon_Time	implementation dependent	Static	
aCurrent_Power_State	implementation dependent	Dynamic	

			
Table 3, MIB Variable Parameters
1.4	 DSSS Physical Medium Dependent Sublayer
1.4.1	 Scope and Field of Application
This section describes the PMD services provided to the PLCP for the DSSS Physical Layer.  Also defined in this section are the functional, electrical, and RF characteristics required for interoperability of implementations conforming to this specification.  The relationship of this specification to the entire DSSS PHY Layer is shown in Figure 101085.

Figure 10, PMD Layer Reference Model
1.4.2	 Overview of Service
The DSSS Physical Medium Dependent Sublayer accepts Physical Layer Convergence Procedure sublayer service primitives and provides the actual means by which data shall be transmitted or received from the media. The combined function of  DSSS PMD sublayer primitives and parameters for the receive function  results in a data stream, timing information, and associated received signal parameters being delivered to the PLCP sublayer.  A similar functionality shall be provided for data transmission. 
1.4.3	 Overview of Interactions
The primitives associated with the 802.11 PLCP sublayer to the DSSS PMD falls into two basic categories:
a)	Service primitives that support PLCP peer-to-peer interactions.
b)	Service primitives that have local significance and support sublayer-to-sublayer interactions.

1.4.4	 Basic Service and Options
All of the service primitives described in this section are considered mandatory unless otherwise specified.
1.4.4.1	 PMD_SAP Peer-to-Peer Service Primitives
Table 4454 indicates the primitives for peer-to-peer interactions.
Primitive	Request	Indicate	Confirm	Response	
PHY_RXSTART		X			
PHY_RXEND		X			
PHY_CCA		X			
PHY_TXSTART	X		X		
PHY_TXEND	X		X		
PHY_DATA	X	X	X		
Table 4, PMD_SAP Peer-to-Peer Service Primitives

1.4.4.2	PMD_SAP Peer-to-Peer Service Primitive Parameters
Several service primitives include a parameter vector.  This vector shall be actually a list of parameters which may vary depending on PHY type. Table 44454 indicates the parameters required by the MAC or DSSS PHY in each of the parameter vectors used for peer-to-peer interactions.
Parameter	Associated Primitive	Value	
LENGTH	RXVECTOR, TXVECTOR	4 to 2^16-1	
SIGNAL	RXVECTOR, TXVECTOR	PHY dependent	
SERVICE	RXVECTOR, TXVECTOR	PHY dependent	
TXPWR_LEVEL	TXVECTOR	PHY dependent	
TX_ANTENNA	TXVECTOR	PHY dependent	
RSSI	RXVECTOR	PHY dependent	
SQ	RXVECTOR	PHY dependent	
RX_ANTENNA	RXVECTOR	PHY dependent	
Table 5, PMD_SAP Peer-to-Peer Service Primitives

1.4.4.3	 PMD_SAP Sublayer-to-Sublayer Service Primitives
Primitive	Request	Indicate	Confirm	Response	
PMD_TXSTART	X				
PMD_TXEND	X				
PMD_ANTSEL	X	X			
PLME_DIVERSITY	X				
PMD_TXPWRLVL	X				
PLME_CHANNEL	X				
PMD_RATE	X	X			
PMD_RSSI		X			
PMD_SQ		X			
PMD_CS		X			
PMD_ED	X	X			
Table 6, PMD_SAP Sublayer-to-Sublayer Service Primitives
1.4.4.4		PMD_SAP Service Primitive Parameters
Parameter	Associate Primitive	Value	
DATA	PHY_DATA.request
PHY_DATA.indicate	octet value:  00-FFh	
TXVECTOR	PHY_DATA.request	a set of parameters	
RXVECTOR	PHY_DATA.indicate	a set of parameters	
TXD_UNIT	PMD_DATA.request	One(1), Zero(0): DBPSK
di bit combinations
00,01,11,10: DQPSK	
RXD_UNIT	PMD_DATA.indicate	One(1), Zero(0): DBPSK
di bit combinations
00,01,11,10: DQPSK	
RF_STATE	PMD_TXE.request	Receive, Transmit	
ANT_STATE	PMD_ANTSEL.indicate
PMD_ANTSEL.request	1 to 256 	
DIV_CONTROL	PLME_DIVERSITY.request	On, Off	
TXPWR_LEVEL	PHY_TXSTART	0,1,2,3 (max of 4 levels)	
CHNL_ID	PLME_CHANNEL.request	1 to 12	
RATE	PMD_RATE.indicate
PMD_RATE.request	h0A for 1 Mb/s DBPSK
h14 for 2 Mb/s DQPSK	
RSSI	PMD_RSSI.indicate	0-8 bits of RSSI 	
SQ	PMD_SQ.indicate	0-8 bits of Signal Quality  	
Table 7, List of Parameters for the PMD Primitives
1.4.5	 PMD_SAP Detailed Service Specification
The following section describes the services provided by each PMD primitive.
1.4.5.1	 PMD_DATA.request
	Function 
This primitive defines the transfer of data from the PLCP sublayer to the PMD entity.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_DATA.request(TXD_UNIT)
The TXD_UNIT parameter takes on the value of either ONE(1) or ZERO(0) for DBPSK modulation or the di-bit combination 00, 01, 11, or 10 for DQPSK modulation.  This parameter represents a single block of data which in turn shall be used by the PHY to be differentially encoded into a DBPSK or DQPSK transmitted symbol.  The symbol itself shall be spread by the PN code prior to transmission.
	When Generated
This primitive shall be generated by the PLCP sublayer to request transmission of a symbol.  The data clock for this primitive shall be supplied by PMD layer based on the PN code repetition.
	Effect of Receipt
The PMD performs the differential encoding, PN code modulation, and transmission of the data.
1.4.5.2	 PMD_DATA.indicate
	Function 
This primitive defines the transfer of data from the PMD entity to the PLCP sublayer.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_DATA.indicate(RXD_UNIT)
The RXD_UNIT parameter takes on the value of  ONE(1) or ZERO(0) for DBPSK modulation or as the di-bit 00, 01, 11, or 10 for DQPSK modulation.  This parameter represents a single symbol which has been demodulated by the PMD entity. 
	When Generated
This primitive generated by the PMD entity, forwards received data to the PLCP sublayer.  The data clock for this primitive shall be supplied by PMD layer based on the PN code repetition.
	Effect of Receipt
The PLCP sublayer either interprets the bit or bits which are recovered as part of the PLCP convergence procedure or pass the data to the MAC layer as part of the MPDU.
1.4.5.3	 PMD_TXSTART.request
	Function 
This primitive, generated by the PHY PLCP sublayer, initiates PPDU transmission by the PMD layer.   
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_TXSTART.request
	When Generated
This primitive shall be generated  by the PLCP sublayer to initiate the PMD layer transmission of the PPDU. The PHY_DATA.request primitive shall be provided to the PLCP sublayer prior to issuing the PMD_TXSTART command. 
	Effect of Receipt
PMD_TXSTART initiates transmission of a PPDU by the PMD sublayer.
1.4.5.4	 PMD_TXEND.request
	Function 
This primitive, generated by the PHY PLCP sublayer, ends PPDU transmission by the PMD layer.   
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_TXEND.request
	When Generated
This primitive shall be generated  by the PLCP sublayer to terminate the PMD layer transmission of the PPDU.
	Effect of Receipt
PMD_TXEND terminates transmission of a PPDU by the PMD sublayer.  
1.4.5.5	 PMD_ANTSEL.request
	Function 
This primitive, generated by the PHY PLCP sublayer, selects the antenna used by the PHY for transmission or reception (when diversity is disabled).
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_ANTSEL.request(ANT_STATE)
ANT_STATE selects which of the available antennas should be used for transmit.  The number of available antennas shall be determined from the MIB table parameters aSuprt_Rx_Antennas and  aSuprt_Tx_Antennas.
	When Generated
This primitive shall be generated  by the PLCP sublayer to select a specific antenna for transmission (or reception when diversity is disabled).
	Effect of Receipt
PMD_ANTSEL immediately selects the antenna specified by ANT_STATE.
1.4.5.6	 PMD_ANTSEL.indicate
	Function 
This primitive, generated by the PHY PLCP sublayer, reports the antenna used by the PHY for reception of the most recent packet.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_ANTSEL.indicate(ANT_STATE)
ANT_STATE reports which of the available antennas was used for reception of the most recent packet.
	When Generated
This primitive shall be generated  by the PLCP sublayer to report the antenna used for the most recent packet reception.
	Effect of Receipt
PMD_ANTSEL immediately reports the antenna specified by ANT_STATE.
1.4.5.7	 PLME_DIVERSITY.request
	Function 
This primitive, generated by the PHY PLME sublayer, selects whether antenna diversity shall be enabled or disabled during reception.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PLME_DIVERSITY.request(DIV_CONTROL)
DIV_CONTROL selects whether the diversity function shall be enabled or not.
	When Generated
This primitive shall be generated  by the PLCP sublayer to change the operating state of the receive state machine to select a specific antenna for reception or to allow diversity function.
	Effect of Receipt
PLME_DIVERSITY immediately alters the receive state machine according to the DIV_CONTROL parameter.
1.4.5.8	 PMD_TXPWRLVL.request
	Function 
This primitive, generated by the PHY PLCP sublayer, selects the power level used by the PHY for transmission.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_TXPWRLVL.request(TXPWR_LEVEL)
TXPWR_LEVEL selects which of the optional transmit power levels should be used for the current packet transmission.  The number of available power levels shall be determined by the MIB parameter NO_TXPWRLVLS.  Clause 1.4.7.3 provides further information on the optional DSSS PHY power level control capabilities.
	When Generated
This primitive shall be generated  by the PLCP sublayer to select a specific transmit power.  This primitive shall be applied prior to setting PMD_TXSTART into the transmit state.
	Effect of Receipt
PMD_TXPWRLVL immediately sets the transmit power level given by TXPWR_LEVEL.
1.4.5.9	 PLME_CHANNEL.request
	Function 
This primitive, generated by the PHY PLME sublayer, selects the channel frequency which shall be used by the DSSS PHY for transmission or reception.  
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PLME_CHANNEL.request(CHNL_ID)
CHNL_ID selects which of the DSSS PHY channel frequencies shall be used for transmission or reception. Clause 1.4.6.2 provides further information on the DSSS PHY channel plan.
	When Generated
This primitive shall be generated  by the PLME sublayer to change or set the current DSSS PHY channel.
	Effect of Receipt
The receipt of  PLME_CHANNEL immediately changes the operating channel as set by the CHNL_ID parameter.
1.4.5.10	 PMD_RATE.request
	Function 
This primitive, generated by the PHY PLCP sublayer, selects the modulation RATE which shall be used by the DSSS PHY for transmission.  
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_RATE.request(RATE)
RATE selects which of the DSSS PHY data rates shall be used for MPDU transmission.   Clause 1.4.6.4 provides further information on the DSSS PHY modulation rates.  The DSSS PHY rate change capability is fully described in clause 1.2.
	When Generated
This primitive shall be generated  by the PLCP sublayer to change or set the current DSSS PHY modulation rate used for the MPDU portion of a PPDU.
	Effect of Receipt
The receipt of  PHY_RATE selects the rate which shall be used for all MPDU transmissions.  This rate shall be used for transmission only.  The DSSS PHY shall still be capable of receiving all the required DSSS PHY modulation rates.
1.4.5.11	 PMD_RATE.indicate
	Function 
This primitive, generated by the PMD sublayer, indicates which modulation rate was used to receive the MPDU portion of the PPDU.  The modulation shall be indicated in the PLCP preamble 802.11 SIGNALING field. 
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_RATE.indicate(RATE)
In receive mode, the RATE parameter informs the PLCP layer which of the DSSS PHY data rates was used to process the MPDU portion of the PPDU.  Clause 1.4.6.4 provides further information on the DSSS PHY modulation rates.  The DSSS PHY rate change capability is fully described in section 1.2.
	When Generated
This primitive shall be generated  by the PMD sublayer when the PLCP preamble 802.11 SIGNALING field has been properly detected.
	Effect of Receipt
This parameter shall be provided to the PLCP layer for information only. 
1.4.5.12	 PMD_RSSI.indicate
	Function 
This optional primitive, generated by the PMD sublayer, provides to the PLCP and MAC entity the Received Signal Strength.
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_RSSI.indicate(RSSI)
The RSSI shall be a measure of the RF energy received by the DSSS PHY.  RSSI indications of up to 8 bits (256 levels) are supported.
	When Generated
This primitive shall be generated  by the PMD when the DSSS PHY is in the receive state.  It shall be continuously available to the PLCP which in turn provides the parameter to the MAC entity. 
	Effect of Receipt
This parameter shall be provided to the PLCP layer for information only.  The RSSI may be used in conjunction with SQ as part of a Clear Channel Assessment scheme.
1.4.5.13	 PMD_SQ.indicate
	Function 
This optional primitive, generated by the PMD sublayer, provides to the PLCP and MAC entity the Signal Quality of the DSSS PHY PN code correlation.  The signal quality shall be sampled when the DSSS PHY achieves code lock and held until the next code lock acquisition. 
	Semantic of the Service Primitive
The primitive shall provide the following parameters:
PMD_SQ.indicate(SQ)
The SQ shall be a measure of the PN code correlation quality received by the DSSS PHY.  SQ indications of up to 8 bits (256 levels) are supported.
	When Generated
This primitive shall be generated  by the PMD when the DSSS PHY is in the receive state and code lock is achieved.  It shall be continuously available to the PLCP which in turn provides the parameter to the MAC entity. 
	Effect of Receipt
This parameter shall be provided to the PLCP layer for information only.  The SQ may be used in conjunction with RSSI as part of a Clear Channel Assessment scheme.
1.4.5.14	 PMD_CS.indicate
This primitive, generated by the PMD, shall indicate to the PLCP layer that the receiver has acquired (locked) the PN code and data is being demodulated.
	Function
This primitive, generated by the PMD, shall indicate to the PLCP layer that the receiver has acquired (locked) the PN code and data is being demodulated.   
	Semantic of the Service Primitive
The PMD_CS (Carrier Sense) primitive in conjunction with PMD_ED provide CCA status through the PLCP layer  PHY_CCA primitive.   PMD_CS  indicates a binary status of ENABLED or DISABLED.  PMD_CS shall be ENABLED when the correlator signals quality indicated in PMD_SQ is greater than the CS_THRESHOLD parameter.  PMD_CS shall be DISABLED when the PMD_SQ falls below the correlation threshold.
	When Generated
This primitive shall be generated  by the PHY sublayer when the PHY is receiving  PPDU and the PN code has been acquired. 
	Effect of Receipt
This indicator shall be provided to the PLCP  for forwarding to the MAC entity for information purposes through the PHY_CCA indicator.  This parameter shall indicate that the RF media is busy and occupied by a DSSS PHY signal.  The DSSS PHY should not be placed into the transmit state when PMD_CS is ENABLED.
1.4.5.15	 PMD_ED.indicate
	Function 
This optional primitive, generated by the PMD, may indicate to the PLCP layer that the receiver has detected RF energy indicated by the PMD_RSSI  primitive which is above a predefined threshold.   
	Semantic of the Service Primitive
The PMD_ED (Energy Detect) primitive along with the PMD_SQ provide CCA  status at the  PLCP layer through the PHY_CCA primitive.   PMD_ED  indicates a binary status of ENABLED or DISABLED.  PMD_ED shall be ENABLED when the RSSI indicated in PMD_RSSI  is greater than the ED_THRESHOLD parameter.  PMD_ED shall be DISABLED when the PMD_RSSI falls below the energy detect threshold.
	When Generated
This primitive shall be generated  by the PHY sublayer when the PHY is receiving RF energy from any source which exceeds the ED_THRESHOLD parameter.
	Effect of Receipt
This indicator shall be provided to the PLCP  for forwarding to the MAC entity for information purposes through the PMD_ED indicator.  This parameter shall indicate that the RF media may be busy with an RF energy source which is not DSSS PHY compliant.  If a DSSS PHY source is being received, the PMD_CS function shall be enabled shortly after the PMD_ED function is enabled.

1.4.5.16	 PMD_ED.request
	Function 
This optional primitive, generated by the PHY PLCP, sets the energy detect ED THRESHOLD value.   
	Semantics of the Service Primitive
The primitive shall provide the following parameters:
PMD_ED.request(ED_THRESHOLD)
ED_THRESHOLD sets the threshold which the RSSI indicated shall be greater than in order for PMD_ED to be enabled.
	When Generated
This primitive shall be generated by the PLCP sublayer to change or set the current DSSS PHY energy detect threshold.
	Effect of Receipt
The receipt of  PMD_ED immediately changes the energy detection threshold as set by the ED_THRESHOLD parameter.

1.4.5.17	 PHY_CCA.indicate
	Function 
This primitive, generated by the PMD, indicates to the PLCP layer that the receiver has detected RF energy which adheres to the CCA algorithm.   
	Semantic of the Service Primitive
The PHY_CCA primitive provides CCA status at the  PLCP layer to the MAC.
	When Generated
This primitive shall be generated  by the PHY sublayer when the PHY is receiving RF energy from any source which exceeds the ED_THRESHOLD parameter (PMD_ED is active) and optionally is a valid correlated DS-PHY signal whereby PMD_CS would also be active.
	Effect of Receipt
This indicator shall be provided to the PLCP  for forwarding to the MAC entity for information purposes through the PHY_CCA indicator.  This parameter indicates that the RF media may be busy with an RF energy source which may or may not be DSSS PHY compliant.  If a DSSS PHY source is being received, the PMD_CS function shall be enabled shortly after the PMD_ED function is enabled.
1.4.6		PMD Operating Specifications General
The following sections provide general specifications for the DSSS Physical Medium Dependent sublayer. These specifications apply to both the receive and the transmit functions and general operation of a DSSS PHY. 
1.4.6.1		Operating Frequency Range
The DSSS PHY shall operate in the frequency range of 2.4 to 2.4835 GHz as allocated by regulatory bodies in the USA and Europe or in the 2.471 to 2.497 GHz frequency band as allocated by regulatory authority in Japan. 
1.4.6.2		Number of Operating Channels
For the 2.4 to 2.4835 GHz  frequency band, 11 channels are specified.  The channel center frequencies and CHNL_ID numbers shall be as shown in Table 8858 for FCC (North America) and ETSI (Europe).  For Japan, operation shall be specified as 2.471 to 2.497 GHz.  CHNL_ID 12 shall be specified for operation in Japan.  For the FCC domain all channels 1-11 shall be supported and for the ETSI domain channels 3-11 shall be supported.

CHNL_ID	FCC Channel
Frequencies	ETSI Channel
Frequencies	Japan
Frequency	
1	2412 MHz	N/A	N/A	
2	2417 MHz	N/A	N/A	
3	2422 MHz	2422 MHz	N/A	
4	2427 MHz	2427 MHz	N/A	
5	2432 MHz	2432 MHz	N/A	
6	2437 MHz	2437 MHz	N/A	
7	2442 MHz	2442 MHz	N/A	
8	2447 MHz	2447 MHz	N/A	
9	2452 MHz	2452 MHz	N/A	
10	2457 MHz	2457 MHz	N/A	
11	2462 MHz	2462 MHz	N/A	
12	N/A	N/A	2484 MHz	
Table 8, DSSS PHY Frequency Channel Plan
In a multiple cell network topology, overlapping and/or adjacent cells using different channels can operate simultaneously without interference if the distance between the center frequencies is at least 30 MHz.  Channel 12 shall be designated specifically for operation in Japan.
1.4.6.3		Spreading Sequence
The following 11 chip Barker sequence shall be used as the PN code sequence:
+1, -1,+1,+1, -1,+1, +1, +1, -1, -1, -1
The left most chip shall be output first in time.  The first chip shall be aligned at the start of a transmitted symbol.  The symbol duration shall be exactly 11chips long.
1.4.6.4		Modulation and Channel Data Rates
Two modulation formats and data rates are specified for the DSSS PHY:  a Basic Access Rate and an Enhanced Access Rate.  The Basic Access Rate shall be based on 1 Mb/s  DBPSK modulation.  The DBPSK encoder is specified in Table 9959.  The Enhanced Access Rate shall be based on 2 Mb/s DQPSK.  The DQPSK encoder is specified in Table 101060.  (In the tables, +j shall be defined as counterclockwise rotation.)
Bit Input	Phase Change (+j)	
0	0	
1		
Table 9, 1 Mb/s DBPSK Encoding Table

Dibit pattern (d0,d1)
d0 is first in time	
Phase Change (+j)	
00	0	
01	/2	
11		
10	3/2   (-/2)	
Table 10, 2 Mb/s DQPSK Encoding Table
1.4.6.5		Transmit and Receive In Band and Out of Band Spurious Emissions
The DSSS PHY shall conform with in-band and out-of-band spurious emissions as set by regulatory bodies. For the USA,  refer to FCC 15.247, 15.205, and 15.209.  For Europe, refer to ETS 300-328.
1.4.6.6		Transmit to Receive Turnaround Time
The TX to RX turnaround time shall be less than 10 usec including the power down ramp specified in section 1.4.7.7.
The TX to RX turnaround time shall be measured at the air interface from the trailing edge of the last transmitted symbol to valid CCA detection of incoming signal.  The CCA should occur within 25 usec (10 usec for turnaround time plus 15 usec for energy detect) or by the next slot boundary occuring after the 25 usec has elapsed (refer to clause 1.4.8.4).  A receiver input signal 3dB above the ED threshold described in clause 1.4.8.4 shall be present at the receiver.
1.4.6.7		Receive to Transmit Turnaround Time
The RX to TX turnaround time shall be measured at the MAC/PHY interface, using PHY_DATA.request(START-OF-DATA) and shall be less than or equal to 5 usec.  This includes the transmit power up ramp described in clause 1.4.7.7.
1.4.6.8		Slot Time
The slot time for the DSSS PHY shall be the sum of  the RX to TX turnaround time (5 usec) and the energy detect time (15 usec specified in clause 1.4.8.4).  The propagation delayshall be regarded to be included in the energy detect time.
1.4.6.9		Transmit and Receive Antenna Port Impedance
The transmit and receive antenna port(s) impedance shall be 50 if the port is exposed.
1.4.6.10	 Transmit and Receive Operating Temperature Range
Two temperature ranges for full operation compliance to the DSSS PHY are specified.  Type 1 shall be defined as 0C to 40C is designated for office environments.  Type 2 shall be defined as -30C to +70C and is designated for industrial environments. 
1.4.7	 PMD Transmit Specifications
The following sections describe the transmit functions and parameters associated with the Physical Medium Dependent sublayer. 
1.4.7.1		Transmit Power Levels
The maximum allowable output power as measured in accordance  with practices specified by the regulatory bodies is shown in Table 111161.  In the USA, the radiated emissions should also conform with the ANSI uncontrolled radiation emission standards (ANSI/IEEE C95.1-1992 or IEEE C95.1-1991).  
Maximum Output Power  	Geographic Location	Compliance Document	
1000 mW	USA	FCC 15.247	
100 mW (EIRP)	EUROPE	ETS 300-328	
10 mW/MHz	JAPAN	MPT ordinance 79	
Table 11, Transmit Power Levels
1.4.7.2		Minimum Transmitted Power Level
The minimum transmitted power shall be no less than 1 mW.
1.4.7.3		Transmit Power Level Control
Power control shall be provided for transmitted power greater than 100 mW.  A maximum of 4 power levels may be provided.  At a minimum, a radio capable of transmission greater than 100 mW shall be capable of switching power back to 100 mW or less.
1.4.7.4		Transmit Spectrum Mask
The transmitted spectral products shall be less than -30 dBr (dB relative to  the SINx/x  peak) for fc -22 MHz < f < fc -11 MHz and  fc +11 MHz < f < fc + 22 MHz and -50 dBr for  f < fc -22 MHz and f > fc + 22 MHz where fc is the channel center frequency.  The transmit spectral mask is shown in Figure 111186. The measurements shall be made using 100 KHz resolution bandwidth and a 30 KHz video bandwidth.

Figure 11, Transmit Spectrum Mask
1.4.7.5		Transmit Center Frequency Tolerance
The transmitted center frequency tolerance shall be +/- 25 ppm maximum.
1.4.7.6		Chip Clock Frequency Tolerance
The PN code chip clock frequency tolerance shall be better than +/- 25ppm maximum.
1.4.7.7		Transmit Power On and Power Down Ramp 
The transmit power on ramp for 10% to 90% of maximum power shall be no greater than 2 usec.  The transmit power on ramp is shown in Figure 121287.

Figure 12, Transmit Power On Ramp
The transmit power down ramp for 90% to 10% maximum power shall be no greater than 2 usec.  The transmit power down ramp is shown in Figure 131388.

Figure 13, Transmit Power Down Ramp
The transmit power ramps shall be constructed such that the DSSS PHY emissions conform with spurious frequency product specification defined in clause 1.4.6.5.
1.4.7.8		RF Carrier Suppression
The RF carrier suppression, measured at the channel center frequency, shall be at least 15 dB below the peak SIN(x)/x power spectrum.  The RF carrier suppression shall be measured while transmitting a repetitive 01 data sequence with the scrambler disabled using DQPSK modulation.  A 100 kHz resolution bandwidth shall be used to  perform this measurement.
1.4.7.9		Transmit Modulation Accuracy
The transmit modulation accuracy requirement for the DSSS PHY shall be based on the difference between the actual transmitted waveform and the ideal signal waveform.  Modulation accuracy shall be determined by measuring the peak vector error magnitude measured during each chip period.  Worst case vector error magnitude shall not exceeded  0.35  for  the normalized  sampled chip data.  The ideal complex  I and Q constellation points associated with DQPSK modulation (0.707,0.707), (0.707, -0.707), (-0.707, 0.707), (-0.707, -0.707) shall be  used as the reference.  These measurements shall be from baseband  I and Q sampled data after recovery through a reference receiver system.
Figure 141489 illustrates the ideal DQPSK constellation points and range of worst case error specified for modulation accuracy.

Figure 14, Modulation Accuracy Measurement Example
Error vector measurement requires a reference receiver capable of carrier lock.  All measurements shall be made under carrier lock conditions.  The distortion induced in the constellation by the reference receiver shall be calibrated and measured.  The test data error vectors described below shall be corrected to compensate for the reference receiver distortion.
The 802.11 vendor compatible radio shall provide an exposed  TX chip clock which shall be used to sample the I and Q outputs of the reference receiver.
The measurement shall be made under the conditions of continuous DQPSK transmission using scrambled all 1's.
The EYE pattern of the I channel shall be used to determine the I and Q sampling point.  The chip clock provided by the vendor radio shall be time delayed such that the samples fall at a 1/2 chip period offset from the mean of the zero crossing positions of the EYE (see Figure 151590 below). This is the ideal center of the EYE and may not be the point of maximum EYE OPENING. 

Figure 15, Chip Clock Alignment with Baseband Eye Pattern
Using the aligned chip clock, 1000 samples of the I and Q baseband outputs from the reference receiver are captured.  The vector error magnitudes shall be calculated as follows:
Calculate the DC offsets for I and Q samples.
	Imean =n=01000I(n)/1000

	Qmean =n=01000Q(n)/1000

Calculate the DC corrected I and Q samples for all N =1000 sample pairs.
	IDC(n)= I(n) - Imean
	QDC(n)= Q(n) - Qmean
Calculate the average magnitude of  I and Q samples.
	Imag = n=01000 |IDC(n)|/1000
	Qmag = n=01000 |QDC(n)|/1000
Calculate the normalized error vector magnitude for the IDC(n)/QDC(n) pairs.
		VERR(n) = sqrt[ 1/2 *( (|IDC(n)|/ Imag)^2 + (|QDC(n)|/ Qmag)^2) ] - VCORRECTION				with VCORRECTION = error induced by the reference receiver system.
A vendor DSSS PHY  implementation shall be compliant if for all N =1000 samples the following condition is met:
	VERR(n) < 0.35
1.4.8	 PMD Receiver Specifications
The following sections describe the receive functions and parameters associated with the Physical Medium Dependent sublayer.
1.4.8.1		Receiver Minimum Input Level Sensitivity
The Frame Error Rate (FER) shall be less than 8*10-2 at a Frame length of 1024 bytes for an input level of -80 dBm measured at the antenna connector.  This FER shall be specified for 2 Mb/s DQPSK modulation.  The test for the minimum input level sensitivity shall be conducted with the energy detection threshold set less than or equal to -80 dBm.
1.4.8.2		Receiver Maximum Input Level
The receiver shall provide a maximum FER of 8*10 -2 at a maximum input level of -4 dBm measured at the antenna.  This FER shall be specified for 2 Mb/s DQPSK modulation.
1.4.8.3		Receiver Adjacent Channel Rejection
Adjacent channel rejection is defined between the two channels in each channel group defined in clause 1.4.6.2. 
The adjacent channel rejection shall be equal to or better than 35 dB with a FER of 8*10 -2 using 2 Mb/s DQPSK modulation described in clause 1.4.6.4.
The adjacent channel rejection shall be measured using the following method:
Input a 2 Mb/s DQPSK modulated signal at a level 6 dB greater than specified in clause 1.4.8.1.  In an adjacent channel (greater than 30 MHz separation as defined by the channel numbering), input a signal modulated in a similar fashion which adheres to the transmit mask specified in clause 1.4.7.4 to a level 41 dB above the level specified in clause 1.4.8.1.  The adjacent channel signal shall be derived from a separate signal source.  It cannot be a frequency shifted version of the reference channel.  Under these conditions, the FER shall be no worse than 8*10 -2.
1.4.8.4		Clear Channel Assessment
The DSSS PHY shall provide the capability to perform Clear Channel Assessment (CCA) according to at least one of the following three methods:
CCA Mode 1:  Energy above threshold.  CCA shall report a busy medium upon detecting any energy above the ED threshold.
CCA Mode 2:  Carrier sense only.  CCA shall report a busy medium only upon the detection of a DSSS signal.  This signal may be above or below the ED threshold.
CCA Mode 3:  Carrier sense with energy above threshold.  CCA shall report a busy medium upon the detection of a DSSS signal with energy above the ED threshold.
The energy detection status shall be given by the PMD primitive, PMD_ED.   The carrier sense status shall be given by PMD_CS.  The status of PMD_ED and PMD_CS are used in the PLCP convergence procedure to indicate activity to the MAC through the PHY interface primitive PHY_CCA.indicate.
A Busy channel shall be indicated by PHY_CCA.indicate of class BUSY. 
Clear Channel shall be indicated by PHY_CCA.indicate of class IDLE.
The PHY MIB attribute aCCA_Mode_Suprt shall indicate the appropriate operation modes. The PHY shall be configured through the PHY MIB attribute aCurrent_CCA_Mode.
The CCA shall be TRUE if there is no energy detect or carrier sense.   The CCA parameters are subject to the following criteria:
a)	The energy detection threshold shall be less than or equal to -80 dBm for TX power > 100 mW, -76 dBm for 50 mW < TX power <= 100 mW, and  -70 dBm for TX power <= 50 mW.

b)	With a valid signal (according to the CCA mode of operation) present at the receiver antenna within 5 usec from a slot boundary, the CCA indicator shall report channel busy before the end of the slot time.  This implies that the CCA signal is available as an exposed test point.
c)	In the event that a correct PLCP Header is received, the DSSS PHY shall hold the CCA signal inactive (channel busy) for the full duration as indicated by the PLCP LENGTH field.  Should a loss of carrier sense occur in the middle of reception, the CCA shall indicate a busy medium for the intended duration of the transmitted packet.

Conformance to DSSS PHY CCA shall be demonstrated by applying a DSSS compliant signal, above the appropriate ED threshold (a), such that all conditions described in (b) and (c) above are demonstrated.