this is useful to ECE STUDENTS

2.  The wireless networks can be classified according to their coverage
areas.
 The smallest coverage area ,where the network is called wireless
personal area network(PAN) is limited to an office.
 A cell of such a small size would enable connecting computers or
electronic input devices
 Example is LAN,SYSTEM INTERCONNECTION
 The largest area covered to the network is called WAN,MAN.

3. •LOCAL AREA NETWORK (LAN)
•SYSTEM INTER CONNECTION
•MERTOPOLITAN AREA
NETWORK(MAN)
•WIDE AREA NETWORK(WAN)

4.  A local area network (LAN) is a group of computers and
associated devices that share a common communications line or
wireless link to a server.
 A LAN is also called IEEE 802.11
 Typically, a LAN encompasses computers and peripherals
connected to a server within a distinct geographic area such as
an office or university campus a commercial establishment.

7. WIRELESS LAN’S and standards
standards Carrier frequency Data rates
IEEE 802.11b
IEEE 802.11a
IEEE 802.11g
2.4 GHZ
5.8 GHZ
2.4 GHZ
10 mbps
20 mbps
20 mbps

8.  The system inter connection is all about the inter connecting
the components of a computer using short-range radio.
Almost every computer has a monitor,keyboard,mouse and
printers connected to the main unit by cable.
 Consequently some companies get to gather to design a
short-range wireless network called BLUETOOTH to
connect these components without wires.
 Bluetooth also allows digital cameras,headsets,scanners and
other devices to connect to a computers by mainly brought
with in range.

10.  A wireless metropolitan area network
connects the residential and visitors to a city.

12.  Finally the most extensive network is a wide area
network which connects the entire country.

15. WIRELESS TELEPHONE NETWORKS
 Highly Dynamic.
 Often Reconfigure for roaming and Handoffs.
 BW constrain ( RF cellular BW).
 No cables required.
FIXED TELEPHONE NETWORKS
 Virtually Static.
 Difficult to change N/W.
 Channel BW can be increased.
 Comprises of Trunks (cables).

16. Local Landline Telephone Network (PSTN)
Resi denti al
custom er
Busi ness
custom er
Resi denti al
custom er
Busi ness
custom er
Cl ass 1:
regi onal centers
Cl ass 2:
sectional centers
Cl ass 3:
pri m ary centers
Cl ass 4:
tol l centers
Cl ass 5:
l ocal central office
Local
l oops
T andem offi ce
Local
l oops
Local Carrier's Domain of Influence, Intra-LATA
Cl ass 1:
regi onal centers
Cl ass 2:
sectional centers
Cl ass 3:
pri m ary centers
Cl ass 4:
tol l centers
Cl ass 5:
l ocal central office
GOLDMAN & RAWLES: ADC3e
FIG. 02-04

20. Developments of Wireless Networks
 First Generation Wireless Networks
 Second Generation Wireless Networks
 Third Generation Wireless Networks
 Fourth Generation Wireless Networks
 Traffic Routing in Wireless Networks
 Circuit Switching
 Packet Switching
 X.25 Protocol

21. Traffic Routing in Wireless Networks
1. Circuit Switching
2. Packet Switching
3. X.25 Protocol

22. Circuit Switching
 There are three phases in circuit switching:
 Establish
 Transfer
 Disconnect
 The telephone message is sent in one go, it
is not broken up.
 The first generation cellular systems
provide connection-oriented services for
each voice user.
 Voice channels are dedicated for users at a
serving base station and network resources
are dedicated to the voice traffic upon
initiation of a call.

23.  That is the “MSC” dedicated a voice channel connected between the base
station and the “PSTN” for the duration of a cellular telephone call.
 When used in conjunction with radio channels. Connection-oriented services
are provided by a technique called “circuit-switching”.
 Since a physical radio channel is dedicated(switched into use) for two way
traffic between the mobile user and the MSC, and the PSTN dedicates a voice
circuit between the MSC and the end-user.

25. Packet Switching
 In packet-based networks, the
message gets broken into small data
packets. These packets are sent out
from the computer and they travel
around the network seeking out the
most efficient route to travel as circuits
become available. This does not
necessarily mean that they seek out the
shortest route.
 Each packet may go a different route
from the others.

26. hsdggdgdgfgfhfhfffPACKET SWITCHING

29. Packet Switching
HEADER USER DATA TRAILER
FLAG ADDRESS
FIELD
CONTROL FIELD INFORMATION
FIELD
FRAME CHECK
SEQUENCE FIELD
Packet Data Format
Fields in a Typical packet data

31. LAYER 1-P
LAYER 2-D
LAYER 3-N
LAYER 4-T
LAYER 1
LAYER 2
LAYER 3
LAYER 1
LAYER 2
LAYER 3
LAYER 1
LAYER 7
LAYER 2
LAYER 3
LAYER 4
LAYER 5
LAYER 6
LAYER 7-A
LAYER 5-S
LAYER 6-P
X.25
X.25
X.25
X.25
X.25
X.25
X.25
X.25
X.25
LAYER 3
LAYER 3
LAYER 3
X.25
X.25
X.25
DTE
SUB SCRIBER
DCE
BASE STATION
MSC
DSE
DCE
BASE STATION
DTE
SUB SCRIBER
X.25 PROTOCAL

32.  X.25 was developed by CCITT to provide
standard connection less network access (packet
switching) protocols for the three lowest layers
(layers 1,2,3) of the open systems
interconnection(OSI MODEL).
DTE:-network interface between originating and terminating equipment (data
terminal equipment.
DCE:-data circuit terminating equipment
DSE:- data switching exchanging

33. X.25 Protocol

35. Format of a Frame in X.25

36. WIRE LESS DATA SERVICES
 We discussion in previous session a circuit switching is inefficient for
dedicated mobile data services such as facsimile(FAX),electronic mail
(E-mail) and short messaging.
 First generation cellular systems that provide data communications
using circuit switching difficulty passing modem signals through the
audio filters of receivers designed for analog , FM ,common air
interfaces .
 In voice filtering must be deactivated when data link must be
established over the common interfaces.
 How ever in 1993 the US cellular systems developed the cellular
digital packet data (CDPD),In 1980’s two other data-only mobile
services called ARDIS& RAM mobile data(RMD). Were developed to
provide packet radio connectivity throughout a network

37. TYPES OF WIRE LESS DATA SERVICES
These are three types of wireless data services
1.Cellular digital packet data (CDPD)
2. Advanced radio data information systems(ARDIS)
3. RAM mobile data(RMD)

38. 1.Cellular digital packet data (CDPD)
MDBS MD-IS IS
MDBS IS
MDBS MD-IS IS
M-ES
M-ES
Fixed
end
system
I-INTERFACE
(INTERNET
OSI NET)
Fig: the CDPD network

39. M-ES : mobile end station
MDBS: mobile data base station
MD-IS: intermediate server for CDPD traffic
 CDPD is a data service for first and second generation US cellular
systems and uses a full 30KHZ AMPS Channel on a shared basis.
 CDPD provides mobile packet data connectivity to existing data
networks and other cellular systems without any additional
bandwidth requirements.
 It also capitalizes on the un used air time which occurs between
successive radio channel assignments by the MSC.
 CDPD does not use the MSC, but rather has its own traffic rather has
its own traffic routing capabilities.
 The first generation AMPS, each CDPD channel is duplex in nature.
 Each CDPD simplex link occupies a 30KHZ RF channel, and data is
sent at 19,200bps. Since CDPD is packet-switched , a large number
of modems, are able to access the same channel on an as needed
packet-by-packet basis.

42.  CDPD supports broadcast, dispatch electronic mail& field monitoring
applications.CDPD transmission are carried out using fixed-length
blocks.
 User data is protected using a reed-Solomon (6347) block code with 6-
bit symbols. For each packet 282 user bits are coded into 378 bit
blocks, which provides correction for up to eight symbols.
 Two lower layers protocols are used
1. the mobile data link protocol (MDLP)
2. the radio resource management protocol(RRMP)
 The MDLP is used to convey information between data link layer
entities (layer 2 devices) across the CDPD air interface.
 The MDLP also provides sequence control to maintain the sequence
order of frames across a data link connection, as well as error detection
and flow control.

43. Link layer characteristics for CDPD
Protocols MDLP, RPMP,X.25
Channel data rate (bps) 19,200
Channel Bandwidth (KHz) 30
Spectrum efficiency (b/Hz) 0.64
Random Error Strategy Cover with burst protect
Burst Error Strategy Rs 63,47 (6 bits per symbol)
Fading Performance With stands 2.2ms fade
Channel accur Slotted DSMA/CD

44. Advance radio data information system(ARDIS)
 Advance radio data information systems (ARDIS) is a private
network serves provided by motorola and IBM and is based on
MDC4800 and RD-LAP (radio data link access procedure)
protocol developed at motorola.
 ARDIS provides 8000MHz two-way mobile data
communication for short-long radio messages in urban and in-
building environments and for user travelling at low speed.
 ARDIS has been developed to provide excellent-in-building
penetration, and long-scale spatial antenna density is used to
receive messages from mobile users.

45. Channel Characteristics for ARDIC
Protocols MDC 4800 RD-LAP
Speed (bps) 4800 19,200
Channel Bandwidth
(KHz)
25 25
Spectrum efficiency
(b/Hz)
0.19 0.77
Random Error Strategy Convolution ½ ,K=7 Trellis coded Modulation rate=3/4
Burst Error Strategy Interleave 16 bits Interleave 32bits
Fading Performance With stands 3.3ms fade Withstands 1.7ms fade
Channel accur CSMA non peanstent Slot CSMA

46. RAM Mobile data (RMD)
 RAM mobile data (RMD) is a public, two-way data service based upon the mobitex
protocol development by ericossion, RAM provides street level coverege for short
and long message for users moving in an urban environment.
 RAM has capability for voice and data transmission but has been designed
primarily for data and facsimiles.
 Fax message are transmitted as normal text to a gate way processor.
 Which than convents the radio message to an approximate format by messaging it
with a black ground page
 The packet-switched wireless transmission consists of a normal length message
instead of a much longer fax image.

47. RAM Mobile data (RMD)
 RAM mobile data (RMD) is a public, two-way data service
based upon the mobitex protocol development by ericossion,
RAM provides street level coverege for short and long
message for users moving in an urban environment.
 RAM has capability for voice and data transmission but has
been designed primarily for data and facsimiles.
 Fax message are transmitted as normal text to a gate way
processor.
 Which than convents the radio message to an approximate
format by messaging it with a black ground page
 The packet-switched wireless transmission consists of a
normal length message instead of a much longer fax image.

48. protocol mobitex
Speed (bps) 8000
Channel band width(KHZ) 12.5
SPECTRAM EFFICIENCY(b/HZ) 0.64
RANDOM ERROR STRATEGY 12,8 HAMMING CODE
BURST ERROR STRATEGY INTERLEAVE 21 BITS
FADING PERFORMANCE WITH STANDS 2.6ms FADE
CHANNEL ACCESS SLOTTED CSMA
CHANNEL CHARACTERISTICS FOR RAM MOBILE DATA

49. Common Channel Signaling
 CCS is a digital communication technique that provides
simultaneous transmission of user data, signaling data and
other related traffic throughout a network
 CCS by out-of-band signaling channels which logically
separate the network data from the user information (voice or
data) on the same channel.
 For second generation wireless communication systems, CCS
is used to pass user data and control signals between the
subscriber and the data station between the base station and the
MSC and between MSCS.
 The concept of CCS implies dedicate, parallel channel, it is
implemented in a TDM format for serial data transmissions.

50. CCS is an out-of –band signaling technique which allows
much faster communication between two nodes with in the
PSTN.
CCS supports signaling data risk from 56kbps to many
mega bits per second.
The signaling channel may be operated in a connation less
fashion where packet data transfer technique are efficiently
used CCS generally uses variable length packet sizes and a
layered protocol structure and CCS used same physical
network connection (i.e fiber optic cable) carries both the
user traffic and the network signaling data.

51. Distributed Central Switching office for CCS
MSC
SMS STP’S STP’S
STP’S STP’S
SEP’S
SS7
SS7
SS7
SS7
SS7
SS7
SEP’S
To other SEP’S
Network-A Network-B

52.  The CCS network architecture is composed of geographically distributed central
switching office each with embedded switching end point (SEP'S) and management
system(SMS),and a Database service management system(DBAS).
 The MSC provides subscriber access to the PSTN via the SEP.
 The SEP implements a stored-program-control-control switching system knows as
the service control point (SCP) that uses CCS to setup calls and to access a network
database.
 The SCP instructs the SEP to center billing records based on the call information
recorded by the SCP.
 The STP controls the switching of message between nodes in the CCS network.

53. For higher reliability of transmission, SEP'S are required to be
connected to the SS7 network via at least two STP'S.
These combination of two STP'S in parallel is known as a mated
pair, and provides connectivity to the network in the execute one
STP fails.
The SMS contains all subscriber records, and also houses toll-free
database which may be excused by the subscribers.
The DBAS is the administrative database that maintains service
records and investigates fraud throughout the network.
The SMS and DBAS work in tandem to provide a wide range of
customer and network provides sences based on SS7