Transcript Systematic Design of Space-Time Trellis Codes for Wireless

ECE 4371, Fall, 2013
Introduction to Telecommunication
Engineering/Telecommunication Laboratory
Zhu Han
Department of Electrical and Computer Engineering
Class 22
Nov. 17th, 2014
Outline

OIS Model
– Overall Architecture
– Functionality

TCP/IP Model
– Overall Architecture
– Functionality

Comparison
OSI Model

The Open Systems Interconnection (OSI) model
– A conceptual model
– Partitioning it into abstraction layers
– Characterizes and standardizes the internal functions of a
communication system

“Open” denotes the ability to connect any two systems which
conform to the reference model and associated standards

The primary Architectural model for inter-computer
communications
3
History of OSI Model

International standard organization (ISO) established a
committee in 1977 to develop an architecture for computer
communication

Open Systems Interconnection (OSI) reference model is the
result of this effort

In 1984, the OSI reference model was approved as an
international standard for communications architecture
4
History of OSI Model

The OSI model is now considered the primary architectural
model for inter-computer communications

The OSI reference model divides the problem of moving
information between computers over a network medium into
– SEVEN smaller and more manageable problems
– This separation into smaller more manageable functions is known
as layering
5
Advantages

Layer architecture simplifies the network design and adds
flexibility
– It is easy to debug network applications in a layered architecture
network
– We do not need to modify the entire host software to include more
communication devices

The network management is easier due to the layered
architecture
– Network layers follow a set of rules, called protocol

Defines the format of the data being exchanged
– The control and timing for the handshake between layers
6
OSI framework architecture

OSI had two major components:
– An abstract model of networking, called the Basic Reference
Model or seven-layer model
– A set of specific protocols
7
OSI in Action

A layer serves the layer above it and is served by the layer below it.

A message begins at the top application layer and moves down the OSI layers to the
bottom physical layer

As the message descends, each successive OSI model layer adds a header to it

Conversely, at the receiving end, headers are striped from the message as it travels
up the corresponding layers
8
Communication Between Each Layer

At each level (N), two entities (layer N
peers) exchange protocol data units (PDUs)
by means of a layer-N protocol.

A service data unit (SDU) is the payload of
a PDU, transmitted unchanged to a peer.

The SDU is a unit of data that is passed
down from one OSI layer to the next-lower
layer, and which the lower layer
encapsulates into a PDU.
– Layer N-1 adds a header or a footer, or
both, to the SDU, composing a PDU of
layer N-1.
– The PDU at a layer N thus becomes the
SDU of layer N-1.
Example – LTE-A
LTE-A Upper Layer Functionality
• Medium Access Control (MAC)
To Evolved Packet Core
NAS
• Radio Link Control (RLC)
• Packet Data Convergence Protocol (PDCP)
IP
RRC
• Radio Resource Control (RRC)
• Non-Access Stratum (NAS)
EUTRAN
•
PDC
P
RLC
MAC
PHY
To Radio
10
Packet formatting
SDU: Service data unit
PDU: Protocol data unit
Data from IP packets
PDCP SDUs
PDCP
PDCP PDUs
PDCP header
PDCP header
K-1
RLC SDUs
PDCP header
K+
K
1
RLC
RLC PDUs
RLC header
MAC SDUs
MAC
MAC PDUs
MAC header
Padding
Transport block
PHY
Slot 0
Slot 1
Slot 2
•••
Slot 17
Slot 18
Slot 19
subframe
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Communication Between Each Layer
Communication Within Each Layer

At each level, two instances at one layer are connected by a
horizontal connection on that layer.
– Two entities (N-entity peers) interact by means of the N protocol by
transmitting protocol data unit.
OSI Layer Functionality
Data unit
Host
layers
Data
Layer
Function
7. Application Network process to application
Data representation, encryption and
6. Presentation decryption, convert machine dependent data
to machine independent data
5. Session
Segments
4. Transport
Packet/Datagram 3. Network
Media
layers Bit/Frame
2. Data link
Bit
1. Physical
Interhost communication, managing sessions
between applications
Reliable delivery of segments between points
on a network.
Addressing, routing and (not necessarily
reliable) delivery of datagrams between
points on a network.
A reliable direct point-to-point data
connection.
A (not necessarily reliable) direct point-topoint data connection.
Physical Layer

Provides physical interface for transmission of information
– Defines rules by which bits are passed from one system to another on a
physical communication medium

Covers all aspects for physical communication





Mechanical
Electrical
Functional
Procedural
Characteristics defined by physical layer






Voltage levels
Timing of voltage changes
Physical data rates
Maximum transmission distances
Physical connectors
And other similar attributes
15
Data Link Layer

Attempts to provide reliable communication over the physical layer
interface
– Handle errors by implementing an acknowledgement and retransmission
scheme

Breaks the outgoing data into frames and reassemble the received
frames
– Implement flow control

Supports points-to-point protocol (PPP) as well as broadcast
communication

The data link layer is divided into two sub-layers:
– Media Access Control (MAC) layer

Responsible for controlling how computers in the network gain
access to data and permission to transmit it.
– Logical Link Control (LLC) layer

Controls error checking and packet synchronization.
16
Network Layer

Implements routing of frames (packets) through the network
– Defines the most optimum path the packet should take from the
source to the destination
– Defines logical addressing so that any endpoint can be identified
– Defines how to fragment a packet into smaller packets to
accommodate different media

Handles congestion in the network
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Transport Layer

Provide a reliable mechanism for the exchange of segment
between two processes in different computers
– Ensures that the data units are delivered error free and in sequence
– Ensures that there is no loss or duplication of data units
– Provides connectionless or connection oriented service
– Provides for the connection management

Compare it with a Post Office
– Deals with the dispatch and classification of mail and parcels sent
18
Session Layer

Provides
– Mechanism for controlling the dialogue between the two end
systems


Defines how to start, control and end conversations between
applications
Responsible for terminating the connection
– Full-duplex, half-duplex, or simplex operation
– Check-pointing mechanism


If a failure of some sort occurs between checkpoints, all data
can be retransmitted from the last checkpoint
Any necessary log-on or password validation is also handled by
this layer
19
Presentation Layer

Defines the format in which the data is to be exchanged between
the two communicating entities
– Transforms data into the form that the application accepts
– Handles data compression and data encryption (cryptography)
20
Application Layer

The highest level of OSI model, closest to the end user,
– Both the OSI application layer and the user interact directly with
the software application

Contains management functions to support distributed
applications

Examples are applications such as file transfer, electronic mail,
remote login etc.
21
Outline

OIS Model
– Overall Architecture
– Functionality

TCP/IP Model
– Overall Architecture
– Functionality

Comparison
TCP/IP Model

The Internet protocol suite

Named for two of its most important protocols:
• Transmission Control Protocol (TCP) and the Internet
Protocol (IP)
– The networking model and a set of communications protocols
used for the Internet and similar networks.

The main design goal of TCP/IP
– Build an interconnection of networks (internetwork or internet)
– Provided universal communication services over heterogeneous
physical networks.
23
TCP/IP Model

The TCP/IP model does not consider the specifics of formatting and
presenting data, and does not define additional layers between the
application and transport layers as in the OSI model (presentation and
session layers).

Organized into four abstraction layers
Application Layer
Application programs using the network
Transport Layer (TCP/UDP)
Management of end-to-end message transmission,
error detection and error correction
Network Layer (IP)
Handling of datagrams : routing and congestion
Data Link Layer
Management of cost effective and reliable data delivery,
access to physical networks
24
Advantages

The enabling of communication between hosts on different
networks, perhaps separated by a large geographical area.

The creation of a standardized abstraction of the communication
mechanisms provided by each type of network.
– Each physical network has its own technology-dependent communication
interface, in the form of a programming interface that provides basic
communication functions (primitives).

The protocol stack allows for division of labor, ease of
implementation and code testing, and the ability to develop
alternative layer implementations.
– A layer provides a service for the layer directly above it and makes use of
services provided by the layer directly below it.
TCP/IP Model
ECE 4371 Fall 2008
Data-Link Layer

Also called the link layer or the network interface layer

The interface to the actual network hardware.

This interface may or may not provide reliable delivery, and
may be packet or stream oriented.

In fact, TCP/IP does not specify any protocol here, but can use
almost any network interface available, which illustrates the
flexibility of the IP layer.
ECE 4371 Fall 2008
Network Layer

Also called the internetwork layer or the inter layer

Provides the “virtual network” image of an internet (this layer
shields the higher levels from the physical network architecture
below it).

Internet Protocol (IP) is the most important protocol in this
layer.
– It is a connectionless protocol that does not assume reliability from
lower layers.

IP does not provide reliability, flow control, or error recovery.
– These functions must be provided at a higher level.
ECE 4371 Fall 2008
Transport Layer

The transport layer provides the end-to-end data transfer by
delivering data from an application to its remote peer.

Multiple applications can be supported simultaneously.

The most-used transport layer protocol is the Transmission
Control Protocol (TCP),
– Provides connection-oriented reliable data delivery, duplicate data
suppression, congestion control, and flow control.
ECE 4371 Fall 2008
Application Layer

The application layer is provided by the program that uses
TCP/IP for communication.

An application is a user process cooperating with another
process usually on a different host (there is also a benefit to
application communication within a single host).

Examples of applications include Telnet and the File Transfer
Protocol (FTP).
ECE 4371 Fall 2008
Outline

OIS Model
– Overall Architecture
– Functionality

TCP/IP Model
– Overall Architecture
– Functionality

Comparison
Comparison with OSI model

In the TCP/IP model of the Internet
– Protocols are not designed into strict layers
as in the OSI model

Compared with the OSI layering
scheme in the following way:
– Application layer includes the OSI
application layer, presentation layer, and
most of the session layer
– Its end-to-end transport layer includes the
graceful close function of the OSI session
layer as well as the OSI transport layer
– The network layer is a subset of the OSI
network layer
Network
Link
– The link layer includes the OSI data link
and physical layers, as well as parts of
OSI's network layer.
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Comparison with OSI model

Examples of application-layer implementations also include:
– On OSI stack:



FTAM File Transfer and Access Management Protocol
X.400 Mail
Common Management Information Protocol (CMIP)
– On TCP/IP stack:




Hypertext Transfer Protocol (HTTP)
File Transfer Protocol (FTP)
Simple Mail Transfer Protocol (SMTP)
Simple Network Management Protocol (SNMP)
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Outline

OIS Model
– Overall Architecture
– Functionality

TCP/IP Model
– Overall Architecture
– Functionality

Comparison
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