Section 2 Users and Networks

Communications Networking:

End-users, Applications and

Network Service Classes

Professor Izhak Rubin

[email protected]

Electrical Engineering Department

UCLA

© 2014 - 2015 by Professor Izhak Rubin

Prof. Izhak Rubin 2

Communications and

Telecommunications Networking

Objective: transport of information from source end users to destination end users

Communications network End users (stationary, mobile)

Nodes (switches / routers, relays)

Links (multiple communications media; wireline; wireless)

Topological layout (tree; mesh; k-connected graph)

Quality of transport Quantity, Accuracy, timeliness,

reliability, availability, security

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ARPANET: Network Layout

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Cyber-geo Map of Internet layouts Visualization Study of the NSFNET, undertaken by Donna Cox and Robert Patterson from the NCSA in 1992.

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Illustrative Network Layout

and Network Flows

A screenshot of a 3D model of

the vBNS network which

connects universities and

laboratories in the USA.

The model was created by Jeff

Brown, a researcher at MOAT,

National Laboratory for

Applied Network Research

(NLANR), USA. The model is

animated to show how traffic

flows over the links.

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Internet MCI Backbone Layout

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Network coverage using

WLANs

Abstract map of some of

the 802.11b wireless base

station nodes in central

London

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Internet

Laptop

Laptop

Laptop

Laptop

Laptop

Laptop

Laptop

Laptop

Laptop

LaptopLaptop

Laptop

Wireless Mesh Network

Mesh

AP Mesh

AP

Mesh

AP

Mesh

AP

Wired Network

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Mobile Ad hoc Wireless

Networks

Internet

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UV aided Autonomous

Mobile Backbone Network

Reference: MBNP-Simulator

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MBN with Multiple UAVs

Reference: MBNP-Simulator

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Networking Using Swarms of UAVs

SWARM 2

SWARM 1

GROUND

SENSORS

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ANet 3

Backbone Node

Gateway

ANet 1

ANet 2

ASPN 1

ASPN 2

Hierarchical Configuration of UV-aided

Mobile Backbone Network (UV-MBN)

The protocol operates in the license-free ISM band at 2.402-2.480 GHz.

To avoid interfering with other protocols that use the 2.45 GHz band, the

Bluetooth protocol divides the band into 79 channels (each 1 MHz wide) and

changes channels up to 1600 times per second.

Implementations with versions 1.1 and 1.2 reach speeds of 723.1 kbit/s.

Version 2.0 implementations feature Bluetooth Enhanced Data Rate (EDR) and

reach 2.1 Mbit/s.

Technically, version 2.0 devices have a higher power consumption, but the

three times faster rate reduces the transmission times, effectively reducing

power consumption to half that of 1.x devices (assuming equal traffic load).

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Bluetooth Networking Bluetooth is a packet-based protocol with a master-slave structure.

One master may communicate with up to 7 slaves in a piconet; all devices share the

master's clock.

Packet exchange is based on the basic clock, defined by the master, which ticks at 312.5 µs

intervals.

Two clock ticks make up a slot of 625 µs; two slots make up a slot pair of 1250 µs. In

the simple case of single-slot packets the master transmits in even slots and receives

in odd slots; the slave, conversely, receives in even slots and transmits in odd slots.

Packets may be 1, 3 or 5 slots long but in all cases the master transmit will begin in

even slots and the slave transmit in odd slots.

A master Bluetooth device can communicate with up to seven devices in a Wireless User

Group. This network group of up to eight devices is called a piconet. The devices can switch

roles, by agreement, and the slave can become the master at any time.

At any given time, data can be transferred between the master and one other device.

The master switches rapidly from one device to another in a round-robin fashion.

Simultaneous transmission from the master to multiple other devices is possible via

broadcast mode, but not used much.

The Bluetooth Core Specification allows connecting two or more piconets together to form a

scatternet, with some devices acting as a bridge by simultaneously playing the master role

in one piconet and the slave role in another.

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Bluetooth Uses

Bluetooth is a standard communications protocol primarily designed for low power consumption, with a

short range (power-class-dependent: 100 m, 10 m and 1 m, but ranges vary in practice) based on low-cost

transceiver microchips in each device. The devices do not have to be in line of sight of each other.

While the Bluetooth Core Specification does mandate minimums for range, the range of the technology is

application specific and is not limited. Manufacturers may tune their implementations to the range needed to

support individual use cases.

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Class Maximum Permitted Power Range

(approximate) mW dBm

Class 1 100 20 ~100 meters

Class 2 2.5 4 ~10 meters

Class 3 1 0 ~1 meters

Version Data Rate

Version 1.2 1 Mbit/s

Version 2.0 + EDR 3 Mbit/s

Version 3.0 + HS 24 Mbit/s

Cellular Wireless Networks:

reuse-k scheduling • Adaptive rate coordinated

scheduling mechanisms used by densely deployed BS nodes in cellular wireless networks. Reuse-1 and reuse-3

Fractional frequency reuse (FFR) (Fig. 1)

Reuse-1 for interior mobiles

Reuse-3 for exterior clients

• absolute fairness

• Proportional fairness

• throughput capacity rates optimized using adaptive scheduling schemes.

17 Prof. Izhak Rubin, EE Dept, UCLA

Reference: papers by Prof. Izhak Rubin et al.

Cellular Wireless Networks:

Directional Scheduling

The throughput metric: maximum fair throughput

capacity rate measured in unit of [bps/Hertz/cell]).

Using a FFR scheme: Reuse-1 for interior mobiles

Reuse-3 for exterior mobiles

Optimal classification (interior and exterior), jointly with:

Optimal Bandwidth Allocation (interior and exterior)

18 Prof. Izhak Rubin, EE Dept, UCLA

Professor Izhak Rubin

Electrical Engineering Department

UCLA

[email protected]

Relay Node

RSU

Client Node

Useful signals

Interfering signal

Vehicular Backbone Network (VBN)

20 Reference: papers by Prof. Izhak Rubin et al.

21 Reference: papers by Prof. Izhak Rubin et al.

What do we want?

Road Side Unit

But, which

car?

Let’s take a

closer look

22

Reference: papers by Prof. Izhak Rubin et al.

A power line communication system for the support of home

networking.

23

Reference: papers by Prof. Izhak Rubin et al.

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Video Streaming

Dynamically Adaptive

Streaming HTTP (DASH)

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3GP-DASH: Transparent end-to-end

packet switched streaming service

with 3GPP file format

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Communications Networking:

End-User

End user Host, terminal, computer, station, laptop, wireless

handset, etc.

Application Time domain and spatial distribution (scope)

Traffic Class Traffic descriptor: average rate, peak rate,

maximum burst duration

Quality of Service (QoS) requirements Per application, per traffic class

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Multi Level Traffic Model

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Traffic Engineering

Random Arrival of flows, calls, bursts, messages, packets

Random duration of underlying activity

Sharing of network storage, processing, computing, networking and communications resources – leading to: Resource contentions

Buffering / Queueing delays

Delay – throughput performance limitations

t

Duration

of activity

Resourc

e

demand

demand

demand

demand demand

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Performance Measures

Statistical; over specified period of time

Throughput: average number of information units received by destination per units time Gross and net throughput measures

Goodput = throughput of correctly (no errors) received data units

Robust Throughput = received correctly uninterrupted (credit gained upon completion of transaction [Rubin] ); e.g., no (or limited) premature breakup of route

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Delay Message and packet delay; interface boundaries (e.g., UNI)

Access delay; network (system) delay; end to end delay

Delay mean, standard deviation, jitter, packet delay variation, 99-percentile, distribution

Packet / message discard rate; call blocking ratio Offered message rate vs. departing message rate

(throughput)

Blocking probability (Grade of Service, GOS, for CS telephone networks and others that employ Call Admission Controls)

Error Rate

Reliability; availability

Performance Measures (cont.)

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Communications Network:

Service Classes

Network offered Service Classes (for QoS transport of corresponding Applications) Constant Bit Rate (CBR)

Real time Variable Bit Rate (rtVBR)

Non Real time Variable Bit Rate (nrtVBR)

Available Bit Rate (ABR)

Unspecified Bit Rate (UBR)

Best effort service

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Communications Network:

Service Classes (cont.)

Service Class Features QoS measures: packet delay, packet delay jitter,

packet discard rate; error rate; availability and reliability

QoS guarantees tied to loading by flow in accordance with traffic descriptor Call / flow admission control

Traffic policing at the User-to-Network Interface (UNI); rate control, traffic shaping

Priorities; differentiated services.

Connection oriented and connectionless operation

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Illustrative Applications and

Services over the Internet

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Broadcast and Multicast

Single message received at multiple stations

Physical layer

Physical layer broadcast

Bus networks

Link

Induced broadcast

Logical bus

Examples: local area networks

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Broadcast and Multicast

(cont.)

Network layer

Broadcast: from a source node

to all network nodes

Multicast: from a source host to

hosts that join a designated

group

Application layer

Multicast destination group by

group membership protocol

sender

receivers

sender

receivers

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Geographical Categorization

Computer Bus

Local Area Networks (LANs)

Metropolitan Area Networks (MANs)

Wide Area Networks (WANs)

Key parameter: propagation delay of signal across the communications media

Per link and end-to-end

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Multi-Media

Physical layer

Different types of communications links

Twisted pair (copper wire), coaxial, fiber-optic, radio-terrestrial, radio-satellite

Application layer

Real-time applications: voice and video

Integrated services network

Broadband-ISDN

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Topology and Connectivity

Mesh Graph

5-connected

Loop Graph (Cycle)

2-connected

Tree Graph =

Connected, no

cycles

1-connected

Star Graph

1-connected

Tree

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Topology and Connectivity

(conti.)

Graph = G = (V,E)

k (line / node) – connected = requires at least

k lines/nodes to fail to disconnect

Observe: fully connected graph with n nodes

uses n(n-1)/2 (FDX)

point-to-point lines. Need to use nodal

switching to make connections on demand.

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Graph Layouts

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Topological Layout – Graphs (1)

Graph = G = (V,E)

Connected graph has at least one path between any pair of nodes

k (line / node) – connected = remains connected under failures of k-1 (or less) lines/nodes;

Requires at least k lines/nodes to fail to disconnect

Menger’s theorem: k-connected graph iff it has k (line/node) disjoint paths between any pair of nodes

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Topological Layout - Graphs (2)

d(i,j) – distance between nodes i and j = length of i-j shortest path

Diameter (G) = max d(i,j) over all nodes.

Degree of node i = deg(i) = number of lines attached to I = number of its neighbors

Number of lines = m(G) = m; number of nodes = n(G) = n

Euler’s Theorem: 2*m = sum [deg(i)] over all nodes

For graph where deg(i) = k, m = nk/2

For k-connected graph, we have deg(i) >=k, for each node i, so that m >= nk/2.

Other connectivity measures: probabilistically based.