The primitives indicate the functions organized by each layer. The PHY layer is responsible for the following tasks:
Ø Activation and deactivation of the radio transceiver
Ø Energy Detection
Ø Link Quality Indication Measurement
Ø Clear Channel Assessment
Ø Data Transmission and Reception
2.6.1.1 Data Transmission
When ever there is data to be transmitted, the MAC layer Management Entity calls upon the PHY layer with these primitives to transmit a data frame.
PD-DATA.request: The PD-DATA.request primitive is generated by a local MAC sublayer entity and issued to its PHY entity to request the transmission of an MPDU. Upon receiving the PDDATA.request primitive, the PHY first constructs a PPDU with the supplied PSDU.
PD-DATA.confirm : The PD-DATA.confirm primitive is generated by the PHY entity and issued to its MAC sublayer entity in response to a PD-DATA.request primitive. The PD-DATA.confirm primitive will return a status of either SUCCESS, indicating that the request to transmit was successful, or an error code of RX ON or TRX OFF, indicating that the transceiver is working in the Receiver mode or the transceiver is switched off.
2.6.1.2 Data Reception
This primitive is used by the PHY layer to notify the MAC layer of the reception of a data packet.
PD-DATA.indication : The PD-DATA.indication primitive is generated by the PHY entity and issued to its MAC sublayer entity to transfer a received PSDU. This primitive will not be generated if the received PSDU Length field is zero or greater than aMaxPHYPacketSize.
2.6.1.3 Clear Channel Assessment
The following primitives implement the Clear Channel Assessment logic. When ever there is data to be transmitted and the node need to compete with its peers using CSMA-CA, it must go through the CCA phase to ascertain if the channel is free/busy. This function is called upon by the MAC Layer Management Entity.
PLME-CCA.request : The PLME-CCA.request primitive is generated by the MLME and issued to its PLME whenever the CSMA-CA algorithm requires an assessment of the channel.
PLME-CCA.confirm : The PLME-CCA.confirm primitive reports the results of a CCA analysis.
2.6.1.4 Energy Detection
The following primitives are responsible for implementing energy detection of the channel. The MAC layer request for such a service and the PHY layer performs the Energy Detection and replies back with the result of the operation.
PLME-ED.request : The PLME-ED.request primitive requests that the PLME perform an ED(Energy Detection) measurement.
PLME-ED.confirm : The PLME-ED.confirm primitive reports back the results of the ED measurement to the MLME.
2.6.1.5 PAN Information Management
The following primitives are subsequently used by the MAC and the PHY layer entities to access a particular PIB value, or either to set a value for a PIB property.
PLME-GET.request: The PLME-GET.request primitive requests information about a given PHY PIB attribute.
PLME-GET.confirm : The PLME-GET.confirm primitive reports the results of an information request from the PHY PIB.
PLME-SET.request : The PLME-SET.request primitive attempts to set the indicated PHY PIB attribute to the given value.
PLME-SET.confirm : The PLME-SET.confirm primitive reports the results of the attempt to set a PIB attribute.
2.6.1.6 Activate/Deactivate Radio Transceiver
The following two primitives are responsible for implementing the function of activating and deactivatingthe transceiver.
PLME-SET-TRX-STATE.request: The PLME-SET-TRX-STATE.request primitive requests that the PHY entity change the internal operating state of the transceiver. The transceiver will have three main states:
Ø Transceiver disabled (TRX OFF)
Ø Transmitter enabled (TX ON)
Ø Receiver enabled (RX ON)
PLME-SET-TRX-STATE.confirm:
The PLME-SET-TRX-STATE.confirm primitive reports the result
of a request to change the internal operating state of the transceiver.
Not all blocks in Figure 2. Logical blocks in the transceiver PHY layer are required to implement a communications system. However, if the functionality is used (even optionally) in the specification, then the cost for implementing the functionality must be included in the cost estimate. The blocks may occur in different orders in the chain, for example, the frequency spreading may be a part of the modulate/demodulate portion or the encryption may precede the source encoding and the decryption follow the source decoding.
Figure 2.11 Logical blocks in the transceiver PHY layer
· Source Encode/Decode – packet formation including headers, data interleaving, error correction/detection (FEC, CRC, etc), compression/decompression. This function is optional, include if it applies to the proposed system.
· Encrypt/Decrypt – bit level operations to protect data. This function is optional, include if it applies to the proposed system.
· Channel encode/decode – bias suppression, symbol spreading/de-spreading (e.g. DSSS), data whitening/de-whitening (or scrambling). This function is optional, include if it applies to the proposed system.
· Modulate/Demodulate – convert digital data to analog format, can include symbol filtering, frequency conversion, frequency filtering.
· Frequency Spreading/De-spreading – can include frequency hopping or other techniques to decrease or increase, respectively, the bits/Hz of the analog signal in the channel. This function is optional, include if it applies to the proposed system.
· Transmit/Receive – transition the signal to/from the channel.
Ø Activation and deactivation of the radio transceiver
Ø Energy Detection
Ø Link Quality Indication Measurement
Ø Clear Channel Assessment
Ø Data Transmission and Reception
2.6.1.1 Data Transmission
When ever there is data to be transmitted, the MAC layer Management Entity calls upon the PHY layer with these primitives to transmit a data frame.
PD-DATA.request: The PD-DATA.request primitive is generated by a local MAC sublayer entity and issued to its PHY entity to request the transmission of an MPDU. Upon receiving the PDDATA.request primitive, the PHY first constructs a PPDU with the supplied PSDU.
PD-DATA.confirm : The PD-DATA.confirm primitive is generated by the PHY entity and issued to its MAC sublayer entity in response to a PD-DATA.request primitive. The PD-DATA.confirm primitive will return a status of either SUCCESS, indicating that the request to transmit was successful, or an error code of RX ON or TRX OFF, indicating that the transceiver is working in the Receiver mode or the transceiver is switched off.
2.6.1.2 Data Reception
This primitive is used by the PHY layer to notify the MAC layer of the reception of a data packet.
PD-DATA.indication : The PD-DATA.indication primitive is generated by the PHY entity and issued to its MAC sublayer entity to transfer a received PSDU. This primitive will not be generated if the received PSDU Length field is zero or greater than aMaxPHYPacketSize.
2.6.1.3 Clear Channel Assessment
The following primitives implement the Clear Channel Assessment logic. When ever there is data to be transmitted and the node need to compete with its peers using CSMA-CA, it must go through the CCA phase to ascertain if the channel is free/busy. This function is called upon by the MAC Layer Management Entity.
PLME-CCA.request : The PLME-CCA.request primitive is generated by the MLME and issued to its PLME whenever the CSMA-CA algorithm requires an assessment of the channel.
PLME-CCA.confirm : The PLME-CCA.confirm primitive reports the results of a CCA analysis.
2.6.1.4 Energy Detection
The following primitives are responsible for implementing energy detection of the channel. The MAC layer request for such a service and the PHY layer performs the Energy Detection and replies back with the result of the operation.
PLME-ED.request : The PLME-ED.request primitive requests that the PLME perform an ED(Energy Detection) measurement.
PLME-ED.confirm : The PLME-ED.confirm primitive reports back the results of the ED measurement to the MLME.
2.6.1.5 PAN Information Management
The following primitives are subsequently used by the MAC and the PHY layer entities to access a particular PIB value, or either to set a value for a PIB property.
PLME-GET.request: The PLME-GET.request primitive requests information about a given PHY PIB attribute.
PLME-GET.confirm : The PLME-GET.confirm primitive reports the results of an information request from the PHY PIB.
PLME-SET.request : The PLME-SET.request primitive attempts to set the indicated PHY PIB attribute to the given value.
PLME-SET.confirm : The PLME-SET.confirm primitive reports the results of the attempt to set a PIB attribute.
2.6.1.6 Activate/Deactivate Radio Transceiver
The following two primitives are responsible for implementing the function of activating and deactivatingthe transceiver.
PLME-SET-TRX-STATE.request: The PLME-SET-TRX-STATE.request primitive requests that the PHY entity change the internal operating state of the transceiver. The transceiver will have three main states:
Ø Transceiver disabled (TRX OFF)
Ø Transmitter enabled (TX ON)
Ø Receiver enabled (RX ON)
PLME-SET-TRX-STATE.confirm:
The PLME-SET-TRX-STATE.confirm primitive reports the result
of a request to change the internal operating state of the transceiver.
Not all blocks in Figure 2. Logical blocks in the transceiver PHY layer are required to implement a communications system. However, if the functionality is used (even optionally) in the specification, then the cost for implementing the functionality must be included in the cost estimate. The blocks may occur in different orders in the chain, for example, the frequency spreading may be a part of the modulate/demodulate portion or the encryption may precede the source encoding and the decryption follow the source decoding.
Figure 2.11 Logical blocks in the transceiver PHY layer
· Source Encode/Decode – packet formation including headers, data interleaving, error correction/detection (FEC, CRC, etc), compression/decompression. This function is optional, include if it applies to the proposed system.
· Encrypt/Decrypt – bit level operations to protect data. This function is optional, include if it applies to the proposed system.
· Channel encode/decode – bias suppression, symbol spreading/de-spreading (e.g. DSSS), data whitening/de-whitening (or scrambling). This function is optional, include if it applies to the proposed system.
· Modulate/Demodulate – convert digital data to analog format, can include symbol filtering, frequency conversion, frequency filtering.
· Frequency Spreading/De-spreading – can include frequency hopping or other techniques to decrease or increase, respectively, the bits/Hz of the analog signal in the channel. This function is optional, include if it applies to the proposed system.
· Transmit/Receive – transition the signal to/from the channel.
