Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
This document specifies Packet Management, LLC, MAC and PHY behaviour. End-to-end services are
provided by protocol layers not specified in this document.
At an application level the system appears as a black box between information packet interfaces and the BPL.
The Bridging function is mandatory and described in section 7. From a bridging standpoint, the layer
management block is connected to the bridging function via a management port. The Convergence Layer is
seen as a set of BPL ports.
The Convergence layer performs the Ethernet Frame to Packet conversion. This function performs the
conversion between Ethernet II/802.3 frames (802.1 p/q tagged or untagged) and 32-bit aligned packets. On the
transmission path, the converter also sets the priority and the OVLAN tag, if needed. The Broadcast/Multicast
handling is also done at this level.
The LLC layer provides peer convergence layers with the ability to exchange LLC service data units
(LSDUs=packets). Given a maximum size constraint on the LPDU payload provided by the layer management,
the LLC segments and/or groups packets into LPDU payloads (burst payloads) to be transferred over the same
transmission port. When several packets are present within a burst payload, inter-packets headers are appended.
In relation with the layer management, the LLC also deals with encryption/decryption of burst payloads. The
LLC will append the burst header to a burst payload.
The MAC layer provides peer LLC layers with the ability to exchange MAC service data units
(MSDUs=LPDUs=burst). On the transmission path, the MAC layer performs the grouping of bursts=MSDU
into an MPDU. The MAC layer also provides the layer management with the ability to generate specific
MPDUs=frames for performing background tasks: silence management, channel estimation, node status polling
and node discovery. The MAC layer handles 7 types of frames (data, silence, channel estimation, polling,
access, access reply and non-returnable data). All these frames start with a token announce delimiter. Except for
the channel estimation frame, all the other frames are terminated with a token delimiter which content depends
on the type of the frame.
The PHY layer performs the OFDM modulation and the digital signal processing (DSP) needed to transmit the
MPDU over the BPL channel. It also adds the FEC redundancy.
3 PHY
This section specifies the Physical Layer Entity for an Orthogonal Frequency Division Multiplexing (OFDM)
system. OFDM has been chosen as the modulation technique because of its inherent adaptability in the presence
of frequency selective channels, its resilience to jammer signals, its robustness to impulsive noise and its
capacity of achieving high spectral efficiencies.
Submission page 36 UPA-OPERA