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IT800D Training

 DLL Overview

 June 2008

Yitran

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 About DLL

2nd Layer (on top of PHY) inthe OSI reference model

DLL = Data Link Layer

IT800 DLL Overview

Provides reliable transit of data across a physical network

link.

 Different DLL specs define different network and protocolcharacteristics, including physical addressing, error 

notification, sequencing of frames and flow control.

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IT800 DLL

Feature List

Packet Transmission & Reception

 Acknowledged & Unacknowledged services

Retransmissions (Acknowledged, Unacknowledged)

Supports Standard (DCSK6), Robust (DCSK4) and ExtremelyRobust transport modes and Adaptive Rate Control

Carrier Sense Multiple Access with Collision Avoidance(CSMA/CA) channel access

Physical Layer Interface Node and Network Addressing

IT800 DLL Overview

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IT800 DLL

Feature List((continued

 Adaptive back-off algorithm based on 802.11 with adaptationfor the power line medium (patent pending)

Network diagnostics and analysis

Simple command language Host interface

Fragmentation and re-assembly of long packets

X-10 detection/coexistence mechanism

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The PHY interface impose strict real-time requirements.

The DLL implements the PHY interface.

The interface supports packet transmission and reception, mediaconditions sensing and physical layer configuration.

IT800 DLL Overview

 Interface to the PHY

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 Node & Network

Addressing The DLL supports a 11 bits device (node) address (2047 nodes pernetwork) and 10 bits network address (1023 logical networks in thesame physical medium).

Each packet contains the network address, the source address(transmitting node) and the destination addresses (target node).

Broadcast transmission to all the nodes in the same network using0x00 as the destination address.

IT800 DLL Overview

 Address assignment and configuration are handled by upper layers

(Application Host).

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Packet Transmission

and Reception

 Application data transmitted in a single burst may be up to 121Bytes.

The maximal payload size is 1912 Bytes (transmitted in fragments).

IT800 DLL Overview

The DLL supports the following packet delivery services:  Ack (Acknowledged)

UnAck (Unacknowledged)

RepUnAck (Repetitive Unacknowledged)

The number of retries in ACK mode and retransmissions in RepUnAck mode are configurable.

Three levels of transmission priority.

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IT800 DLL Overview

CSMA/CA - Carrier Sense Multiple Access with Collision Avoidance.

Collision avoidance is based Adaptive Back-off algorithm – optimized

for Powerline Communications (Yitran’s patent pending algorithm).

Carrier Sense is performed by matched filter detection of IT800symbol – Carrier Detection.

Two levels of Carrier Detection (CD): Response time for the Fast CD is 100/200 usec

Response time for the Full IT800 CD is 800 usec

Channel Access

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IT800 DLL Overview

The Adaptive Back-off mechanism optimizes network performance inscenarios of variable and unknown number of network elementscontending for the channel.

The mechanism optimizes protocol overhead for overload and allowsfor excellent performance during overload with fast recovery.

 Adaptive Back-off 

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IT800 DLL Overview

The DLL supports all PHY layer transmission rates - SM (DCSK6), RM(DCSK4) and ERM.

The DLL maintains a database record of failure and/or success of a

transmission to neighboring nodes in the network.

Based on the database, the DLL supports adaptive rate control tooptimize network performance to the medium conditions.

  Adaptive Rate Control

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IT800 DLL Overview

Simple command language implemented over UART physicalinterface.

Detailed description is provided in a separate presentation.

 Host Interface

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