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WHAT IS WIRELESS ?
• The word wireless is dictionary defined “having no wires ” .
In networking terminology , wireless is the term used to describe any
computer network where there is no physical wired connection
between sender and receiver, but rather the network is connected by
radio waves and or microwaves to maintain communications.
• Wireless networking utilizes specific equipment such as NICs and
Routers in place of wires (copper or optical fibre).
• 1G refers to the first generation of wireless telephone technology,
mobile telecommunications which was first introduced in 1980s and
completed in early 1990s.
• It's Speed was upto 2.4kbps.
• It allows the voice calls in 1 country.
• 1G network use Analog Signal.
• AMPS was first launched in USA in 1G mobile
DRAWBACKS OF 1G
• Poor Voice Quality
• Poor Battery Life
• Large Phone Size
• No Security
• Limited Capacity
• Poor Handoff Reliability
• 2G technology refers to the 2nd generation which is based on GSM.
• It was launched in Finland in the year 1991.
• 2G network use digital signals.
• It’s data speed was upto 64kbps.
It enables services such as text messages,
picture messages and MMS (multi media message).
It provides better quality and capacity
DRAWBACKS OF 2G
• 2G requires strong digital signals to help mobile phones work. If there
is no network coverage in any specific area , digital signals would
• These systems are unable to handle complex data such
• 2.5G is a technology between the second (2G) and third (3G) generation of mobile
• 2.5G is sometimes described as 2G Cellular Technology combined with GPRS.
Send/Receive E-mail Messages
Speed : 64-144 kbps
Take a time of 6-9 mins. to download a 3 mins. Mp3 song
• 3G technology refer to third generation which was
introduced in year 2000s.
• Data Transmission speed increased from
• Typically called Smart Phones and features increased its bandwidth
and data transfer rates to accommodate web-based applications and
audio and video files.
Features Of 3G Technology
Providing Faster Communication
Send/Receive Large Email Messages
High Speed Web / More Security
Video Conferencing / 3D Gaming
TV Streaming/ Mobile TV/ Phone Calls
Large Capacities and Broadband Capabilities
11 sec – 1.5 min. time to download a 3 min Mp3 song.
• The 2g technology was the first U.S. cellular telephone system,
deployed in Chicago in 1983
• It uses digital radio signals, while its predecessor, 1G, was based on
analog radio signals.
• Capable of servicing complex commercial relationships and second
generation of b-to-b ecommerce systems all across the world
• It uses circuit switched domain service.
• Global System for Mobile (GSM):
1. first fully digital system utilizing the 900 MHz frequency band
2. The initial GSM had 200 KHz radio channels, 8 full-rate or 16
half-rate TDMA channels per carrier, encryption of speech,
low speed data services and support for SMS
• Interim Standard 136 (IS-136):
1. In this system, there were 3 full-rate TDMA users over each
30 KHz channel.
• Pacific Digital Cellular (PDC):
This standard was developed in Japan.
1. The main advantage of this standard was its low
transmission bit rate which led to its better spectrum
• Interim Standard 95 (IS-95):
1. Also known as CDMAOne,
2. uses 64 orthogonally coded users and code-words are
transmitted simultaneously on each of 1.25 MHz channels.
3. Certain services are:
- short messaging service,
- slotted paging,
- over-the-air activation,
- enhanced mobile station identities etc.
Pros and Cons Of 2G
• Pros :-
1. The digital signals require very little battery power
2. SMS and email is one of the many 2g technology advantages
3. Improved privacy
• Cons :-
1. Weaker digital signal
2. Angular decay curve
3. Reduced range of sound
2.5G Mobile Networks
• Increased throughput rates in 2G to support modern Internet application, the new
data centric standards were developed is known as 2.5G standard.
• Here, the main upgradation techniques are:
1. supporting higher data rate transmission for web browsing
2. supporting e-mail traffic
3. enabling location-based mobile service
• 2.5G networks also brought into the market some popular application, Like
1. Wireless Application Protocol (WAP)
2. General Packet Radio Service (GPRS)
3. High Speed Circuit Switched Dada (HSCSD)
4. Enhanced Data rates for GSM Evolution (EDGE)
WHAT IS 3G TECHNOLOGY?
● NEXT GENERATION OF WIRELESS TECHNOLOGY THAT TRANSMITS
WIRELESS DATA UPTO 2 MB/Sec.
3G technology comprises three primary standards:
● W- CDMA (wideband code-division multiple access),
● TD-CDMA (time-division CDMA).
Each standard is based on an upgrade path for at least one of today’s
primary wireless interfaces:
● TDMA (time-division multiple-access),
● GSM(Global system for mobile communication)
● CDMA(Code division for multiple access
● FDMA puts each call on a separate frequency.
● Only one subscriber at any given time is assigned to a channel.
● The channel therefore is closed to other conversations until the initial
call is finished, or until it is handed-off to a different channel
● A “full-duplex” FDMA transmission requires two channels, one for
transmitting and the other for receiving.
● FDMA has been used for first generation analog systems.
●TDMA improves spectrum capacity by splitting each frequency into time
● TDMA allows each user to access the entire radio frequency channel for the
short period of a call.
● Other users share this same frequency channel at different time slots.
● The base station continually switches from user to user on the channel.
●TDMA is the dominant technology for the second generation mobile cellular
●A narrow band that is 30 kHz wide.
●Enables a number of mobile phone users to talk simultaneously in the same
area and in the same frequency band.
●The cdma technique is also known as a 'spread spectrum' system as the
digital code spreads the call across the spectrum bandwidth to transmit the
● Uses a special digital code for each user. This code is combined and
transmitted with the voice signal of the individual user across the entire
●CDMA increases spectrum capacity by allowing all users to occupy all
channels at the same time
●Wide band or broad band is considered to include data rates from 64
Kbps to 2 Mbps.
●Wideband channels can carry multiple signals in the same piece of
●Wideband CDMA uses nearly 5MHz per carrier
●WCDMA allows simultaneous access to several voice, video and data
services at once.
• Universal Mobile Telecommunications System (UMTS)
• UMTS is an upgrade from GSM via GPRS or EDGE
• The standardization work for UMTS is carried out by Third
Generation Partnership Project (3GPP)
• Data rates of UMTS are:
• 144 kbps for rural
• 384 kbps for urban outdoor
• 2048 kbps for indoor and low range outdoor
• Virtual Home Environment (VHE)
Application Of 3G
• Mobile TV
• Video on demand
• Video Conferencing
• Location-based services
• Global Positioning System (GPS)
Advantage Of WCDMA
• Large Number Of User Can Permitted And Large Number Of Code Can
• The maximal number of users is interference limited.
• Without knowing the spreading code it is impossible to recover the
• In India, 3G is defined by telecom service providers as minimum 2
Mbps to maximum 28 Mbps.
• 3G networks offer greater security than their 2G predecessors.
Disadvantage Of WCDMA
• High Price To Help Cover the initial Demand And Fixed Cost.
• Needs more towers the high density requires towers to be closer
Global System for Mobile Communications
Originally GSM stood for Groupe Speciale Mobile
GSM to meet the following business objectives
1. Support for international roaming
2. Good speech quality
3. Ability to support handheld terminals
4. Low terminal and service cost
5. Spectral efficiency
6. Support for a range of new services and facilities
7. ISDN compatibility
GSM System Hierarchy
Consists at the minimum one administrative region assigned to
one MSC (Mobile Switching Centre)
Administrative region is commonly known as PLMN (Public
Land Mobile Network)
Each administrative region is subdivided into one or many
Location Area (LA)
One LA consists of many cell groups and each cell group is
assigned to one BSC (Base Station Controller)
For each LA, there will be at least one BSC while cells in one
BSC can belong to different LAs
Cells are formed by the radio areas covered by a BTS (Base
Several BTSs are controlled by one BSC
Traffic from the MS (Mobile Station) is routed through MSC
Calls originating from or terminating in a fixed network or other
mobile networks is handled by the GMSC (Gateway MSC)
Entities in GSM
The Mobile Station (MS) - This includes the Mobile Equipment
(ME) and the Subscriber Identity Module (SIM).
The Base Station Subsystem (BSS) - This includes the Base
Transceiver Station (BTS) and the Base Station Controller (BSC).
The Network and Switching Subsystem (NSS) - This includes
Mobile Switching Center (MSC), Home Location Register (HLR),
Visitor Location Register (VLR), Equipment Identity Register (EIR),
and the Authentication Center (AUC).
The Operation and Support Subsystem (OSS) - This includes the
Operation and Maintenance Center (OMC).
Mobile Station (MS) consists of two main elements: mobile
equipment or mobile device (that is the phone without the SIM
card) and Subscriber Identity Module (SIM)
Terminals distinguished principally by their power and
SIM is installed in every GSM phone and identifies the terminal
SIM cards used in GSM phones are smart processor cards with
a processor and a small memory
SIM card contains the International Mobile Subscriber Identity
(IMSI) used to identify the subscriber to the system, a secret key
for authentication, and other security information
• The Radio Subsystem (RSS) comprises the cellular mobile network up
to the switching centers
– Base Station Subsystem (BSS):
• Base Transceiver Station (BTS): radio components including
sender, receiver, antenna - if directed antennas are used one
BTS can cover several cells
• Base Station Controller (BSC): switching between BTSs,
controlling BTSs, managing of network resources, mapping of
radio channels (Um) onto terrestrial channels (A interface)
• BSS = BSC + sum(BTS) + interconnection
– Mobile Stations (MS)
System architecture: radio subsystem
– Um : radio interface
– Abis : standardized, open interface
16 kbit/s user channels
– A: standardized, open interface with
64 kbit/s user channels
network and switching
Network and Switching Subsystem
Central component of the Network Subsystem is the Mobile
Switching Center (MSC)
Signaling between functional entities in the Network
Subsystem uses Signaling System Number 7 (SS7)
MSC together with Home Location Register (HLR) and Visitor
Location Register (VLR) databases, provide the call-routing and
roaming capabilities of GSM
MSC does the following functions:
1. It acts like a normal switching node for mobile subscribers of
the same network (connection between mobile phone to
mobile phone within the same network)
Network and switching subsystem
• NSS is the main component of the public mobile network GSM
– switching, mobility management, interconnection to other
networks, system control
– Mobile Services Switching Center (MSC)
controls all connections via a separated network to/from a mobile
terminal within the domain of the MSC - several BSC can belong
to a MSC
– Databases (important: scalability, high capacity, low delay)
• Home Location Register (HLR)
central master database containing user data, permanent and
semi-permanent data of all subscribers assigned to the HLR
(one provider can have several HLRs)
• Visitor Location Register (VLR)
local database for a subset of user data, including data about
all user currently in the domain of the VLR
Mobile Services Switching Center
• The MSC (mobile services switching center) plays a central role in GSM
– switching functions
– additional functions for mobility support
– management of network resources
– interworking functions via Gateway MSC (GMSC)
– integration of several databases
• Functions of a MSC
– specific functions for paging and call forwarding
– mobility specific signaling
– location registration and forwarding of location information
– provision of new services (fax, data calls)
– support of short message service (SMS)
– generation and forwarding of accounting and billing information
• The OSS (Operation Subsystem) enables centralized operation,
management, and maintenance of all GSM subsystems
– Authentication Center (AUC)
• generates user specific authentication parameters on request
of a VLR
• authentication parameters used for authentication of mobile
terminals and encryption of user data on the air interface
within the GSM system
– Equipment Identity Register (EIR)
• registers GSM mobile stations and user rights
• stolen or malfunctioning mobile stations can be locked and
sometimes even localized
– Operation and Maintenance Center (OMC)
• different control capabilities for the radio subsystem and the
935 - 960 MHz
Cell Site Mobile
GSM Frequency Allocation
Each way the bandwidth for the GSM system is 25 MHz which
provides 125 carriers uplink/downlink each having a bandwidth of
ARFCN (Absolute Radio Frequency Channel Numbers) denote a
forward and reverse channel pair which is separated in frequency
by 45 MHz.
Practically, a guard band of 100 kHz is provided at the upper
and lower end of the GSM 900 MHz spectrum and only 124
(duplex) channels are implemented.
GSM Frequency Allocation
GSM uses TDMA and FDMA
One or more carrier frequencies are assigned to each base
station and each of these carrier frequencies is then divided in
time using a TDMA scheme where fundamental unit is called a
burst period lasting approximately 0.577 ms.
Eight burst periods are grouped into a TDMA frame of
approximately 4.615 ms which forms the basic unit for the
definition of logical channels.
One physical channel is one burst period per TDMA frame
while, normally, channels are defined by the number and position
of their corresponding burst periods.
GSM Frequency Allocation
Carrier frequencies and TDMA frames
tch –traffic control channel
Sacch-slow associated control channel
What is GPRS
General Packet Radio Service
•General -> not restricted to GSM use (3rd generation systems)
•Packet Radio -> enables packet mode communication over air
•Service, not System -> existing BSS (partially also NSS) infrastructure is used
•Resources are reserved only when needed and charged accordingly
•Connection setup times are reduced
•Enables new service opportunities
Data Services: GPRS
• Bearer services for GPRS offer end-to-end packet-switched data
transfer. Two types:
• Point-to-point (PTP)
• Internet access
• SMS messages
• Point-to-multipoint (PTM)
• Unidirectional distribution of information (e.g. weather, news)
• Conferencing services between multiple users
Quality of Service
• QoS profiles can be defined using parameters derived from service
precedence, reliability, delay and throughput.
• QoS profiles can be negotiated between the mobile user and the
network, per session, depending on current resources, and can affect
• Three priorities: High, Medium, Low
• Three reliability classes that guarantee maximum values of loss,
duplication, mis-sequencing and corruption of packets
• Delay defines maximum mean delay and 95-percentile delay
• Throughput specifies peak and mean bit-rate
GPRS and Conventional GSM
• GSM/GPRS services can be used in parallel. Three classes of mobile
• Class A – Simultaneous use of GSM and GPRS
• Class B – Can register for both GSM and GPRS, but only use one at a time
• Class C – Can attach for only either GSM or GPRS (with the exception of SMS
Uplink/downlink - GPRS
• The uplink channel is shared by a number of mobiles, and its
use is allocated by a BSC (Base Station Controller)
• The MS (Mobile Station) requests use of the channel in a “packet
random access message”.
• The BSC allocates an unused channel to the mobile and sends a
“packet access grant message” in reply
• The downlink is fully controlled by the serving BSC and
random access is not needed
SGSN: Serving GPRS Support Node
GGSN: Gateway GPRS Support Node
EIR – Equipment Identity Register
AuC – Authentication Center
SGSN and GGSN
• SERVING GPRS SUPPORT NODE (SGSN):
• Responsible for authentication, registration and mobility management of mobiles in
• GATEWAY GPRS SUPPORT NODE (GGSN):
• Acts as an interface and a router to external networks.
• Contains routing information for GPRS mobiles which is used to tunnel packets
through the IP based internal backbone to the correct Serving GPRS Support Node.
• Also collects charging information connected to the use of the external data
networks and can act as a packet filter for incoming traffic.
• Internal Backbone:
• The internal backbone is an IP based network used to carry packets between
• ACTIVE STATE:
• Data is transmitted between an MS and the network only when the MS is in
the active state. Here, the SGSN knows the cell location of the MS.
• Packet transmission to an active MS is initiated by packet paging.
• It notifies the MS of an incoming data packet.
• Data transmission then proceeds on the channel indicated by the paging
• The purpose of the paging message – to simplify the process of receiving
• The MS listens to only the paging messages instead of to all the data packets
in the downlink channels. This reduces battery usage significantly.
• STANDBY STATE:
• Only the routing area of the MS is known. (It can consist of one or more cells within a GSM
• When the SGSN sends a packet to an MS that is in the standby state, the MS must be paged.
• A packet paging message is sent to the routing area.
• MS relays its cell location to the SGSN to establish the active state.
• IDLE STATE:
• Not possible to send messages to the MS from external data networks.
• The MS does not have a logical GPRS context activated or any packet-switched public data
network (PSPDN) addresses allocated.
• ROUTING UPDATES:
• When an MS that is in an active or a standby state moves from one routing area to another
within the service area of one SGSN, it must perform a routing update.
• The routing area information in the SGSN is updated, and the success of the procedure is
indicated in the response message.
• “Overview of The Gsm Sysyem And Protocol architechture” IEEE Paper
Published By Moe Rahema.
• “Characterizing Data Services in a 3G Network” IEEE Paper Published By
Zhichao Zhu 2011.
• “On Antena And Frequency Diversity In GSM related systems” IEEE Paper
Published By preben E.Mogensen And Jeroen wihard.
• “Frequency Coordination Between UMTS And GSM System” IEEE Paper
Published By Jiang jindi Huawei Technologies.
• “GPRS: Architechture, Protocols, And Air Interface” IEEE Paper Published By
Christian Bettstetter, Hans-Jotg Eberspacher and Jorg Eberspacher.