Datasheet

M16C/6S Group APPENDIX
R01DS0201EJ0502 Rev.5.02 page 202 of 203
Dec 25, 2012
IT800DLL Explanatory Note
June 2, 2005
3. IT800DLL Main functions
The DLL main functions and mechanisms are described in the following table:
As can be seen from the table above, the IT800 DLL implements enhanced functionality, provides best
performance in terms of channel access and throughput (based on Carrier Sense signaling, Adaptive
Back-off algorithm and packet prioritization), reliable data transfer (using acknowledgement and repeti-
tion mechanisms, multi-hop transmissions and packet filtering) and allows easy integration of IT800
based solution with different protocol stacks. Another important advantage of using IT800DLL is assuring
the co-existence between different IT800 based products operating in the same environment.
Function Description
Carrier sense Provides the carrier detection (CD) signal for triggering the media
access algorithms as a function of the PHY correlator output, which
indicates the probability of a signal on the line
.
Channel access
prioritization
Determines the sequence and time of packet transmissions for a PLC
node, where the highest priority packet nodes participate in the DLL
contention for the media access
.
Adaptive back-off Spreads the time over which a PLC node contends for the channel
using a uniform distribution of the transmissions number over a given
period of time (Yitran patent pending). This mechanism provides high
efficiency of the network functionality, optimal utiliziation of the
channel and sustains a viable network even in cases where many nodes
contend for the channel simultaneously
.
Acknowledgement Serves for informing the transmitting node about the success or
failure of a packet delivery to a target node by means of a traffic-free
acknowledgement window
.
Repetitive un-
acknowledgement
This mechanism is used for transmitting packets a pre-determined
number of times without requiring a reception acknowledgement from
the target node
.
Multiple hop broadcast Retransmits single-network broadcast packets and CNC (Control
Network Channel) messages to all the nodes participating in the same
logical network
.
Fragmentation and
reassembly
Transfers packets longer than the maximal packet size allowed by the
PHY by means of fragmentation in the transmitting node and
reassembly in the receiving nod
e
Packet filtering Filters received packets according to their type for transferring only
pre-defined types of messages to the upper layers and rejecting impostor
node or other types of messages that are not required
.
Copyright © 2005, YITRAN Communications Ltd.