MOBILE COMMUNICATIONS_SEC 2E skill devep

MC notes for refrence

1. MOBILE COMMUNICATIONS

2. DEFINITION
•Mobile communications refers to a form of communications which does not
depend on a physical connection between the sender and receiver.
•It facilitates the users to move from one physical location to another during
communication.

3. INTRODUCTION TO MOBILE COMMUNICATION
•Mobile Communicationis the use of technology that allows us to communicate with
others in different locations without the use of any physical connection (wires or
cables).
•Mobile communication makes our life easier, and it saves time and effort.
•A mobile phone(also called mobile cellular network, cell phone or hand phone) is
an example of mobile communication (wireless communication).
•It is an electric device used for full duplex two way radio telecommunication over a
cellular network of base stations known as cell site.

4. FEATURES OF MOBILE COMMUNICATION
•The following are the features of mobile communication:
•High capacity load balancing:Each wired or wireless infrastructure must
incorporate high capacity load balancing.
•High capacity load balancing means, when one access point is overloaded,
the system will actively shift users from one access point to another depending
on the capacity which is available.

5. SCALABILITY
•The growth in popularity of new wireless devices continuously increasing day
by day.
•The wireless networks have the ability to start small if necessary, but expand
in terms of coverage and capacity as needed -without having to overhaul or
build an entirely new network.

6. NETWORK MANAGEMENT SYSTEM:
•Now a day, wireless networks are much more complex and may consist of
hundreds or even thousands of access points, firewalls, switches, managed
power and various other components.
•The wireless networks have a smarter way of managing the entire network
from a centralized point.

7. ROLE BASED ACCESS CONTROL:
•Role based access control (RBAC) allows you to assign roles based on what,
who, where, when and how a user or device is trying to access your network.
•Once the end user or role of the devices is defined, access control policies or
rules can be enforced.

8. •Indoor as well as outdoor coverage options:It is important that your wireless system has the
capability of adding indoor coverage as well as outdoor coverage.
•Network access control:Network access control can also be called as mobile device
registration.
•It is essential to have a secure registration.
Network access control (NAC) controls the role of the user and enforces policies.
•NAC can allow your users to register themselves to the network.
•It is a helpful feature that enhances the user experience.
•Mobile device management:Suppose, many mobile devices are accessing your wireless
network; now think about the thousands of applications are running on those mobile devices.
•How do you plan on managing all of these devices and their applications, especially as
devices come and go from your business?
•Mobile device management can provide control of how you will manage access to programs
and applications. Even you can remotely wipe the device if it is lost or stolen.

9. •Roaming:You don't need to worry about dropped connections, slower speeds
or any disruption in service as you move throughout your office or even from
building to building wireless needs to be mobile first.
Roaming allows your end-users to successfully move from one access point to
another without ever noticing a dip in a performance.
For example, allowing a student to check their mail as they walk from one
class to the next.
•Redundancy:The level or amount of redundancy your wireless system
requires depends on your specific environment and needs.
•For example:A hospital environment will need a higher level of redundancy
than a coffee shop. However, at the end of the day, they both need to have a
backup plan in place.

10. •Proper Security means using the right firewall:The backbone of the system
is your network firewall. With the right firewall in place you will be able to:
•See and control both your applications and end users.
•Create the right balance between security and performance.
•Reduce the complexity with:
•Antivirus protection.
•Deep Packet Inspection (DPI)
•Application filtering
•Protect your network and end users against known and unknown threads including:
•Zero-day.
•Encrypted malware.
•Ransomware.
•Malicious botnets.

11. •Switching:Basically, a network switch is the traffic cop of your wireless
network which making sure that everyone and every device gets to where
they need to go.
Switching is an essential part of every fast, secure wireless network for
several reasons:
•It helps the traffic on your network flow more efficiently.
•It minimizes unnecessary traffic.
•It creates a better user experience by ensuring your traffic is going to the right places.

12. ADVANTAGES OF MOBILE COMMUNICATION
•There are following advantages of mobile communication:
•Flexibility:Wireless communication enables the people to communicate with each other regardless
of location. There is no need to be in an office or some telephone booth in order to pass and
receive messages.
•Cost effectiveness:In wireless communication, there is no need of any physical infrastructure
(Wires or cables) or maintenance practice. Hence, the cost is reduced.
•Speed:Improvements can also be seen in speed. The network connectivity or the accessibility was
much improved in accuracy and speed.
•Accessibility:With the help of wireless technology easy accessibility to the remote areas is
possible. For example, in rural areas, online education is now possible. Educators or students no
longer need to travel to far-flung areas to teach their lessons.
•Constant connectivity:Constant connectivity ensures that people can respond to emergencies
relatively quickly. For example, a wireless device like mobile can ensure you a constant connectivity
though you move from place to place or while you travel, whereas a wired landline can't.

13. History of Wireless
Communication
The history of the wireless communications
started with the understanding of magnetic
and electric properties observed during the
early days by the Chinese, Roman and Greek
cultures and experiments carried out in the
17th and 18th centuries. A short history of
wireless communication is presented in the
tabular form:
Year Description
1880 Hertz-RadioCommunication
1897 Marconi-RadioTransmission
1933 FCC(FederalCommunicationCommission)
1938 FCCrulesforregularservices
1946 Belltelephonelaboratories52MHz
1956 FCC-450MHz(Simplex)
1964 Belltelephoneactiveresearch800MHz
1964 FCC-450MHz(FullDuplex)
1969 FCC-40MHzbandwidth
1981 FCC?releaseofcellularlandphoneinthe40MHz
1982 At&TdivestedandServerRBOC(RegionalBellOperationCompanies)
formedtomanagethecellularoperation.
1984 MostRBOCmarketinoperations
1986 FCCallocates5MHzextendedband.
1988 TDMAvotedasdigitalcellularstandardinNorthAmerica.
1992 GSM(GroupSpecialMobile)operableGermanyD2system.
1993 CDMA(CodeDivisionMultipleAccess)
1994 PDCC(PersonalDigitalCellularOperable)inTokyo,Japan
1995 CDMAoperableinHongKong
1996 SixBroadBandPCS(PersonalCommunicationServices)licensedbands(120
MHz)almostreader20billionUSdollar
1997 BroadbandCDMAconstructedandofthe3rdgenerationmobile.
1999 PowerfulWLANsystemswereevolved,suchasBluetooth.Thisuses2.4
MHzspectrum.

14. GENERATIONS OF WIRELESS COMMUNICATION
•1G
•This is the first generation of wireless telephone technology, mobile telecommunications, which
was launched in Japan by NTT in 1979.
•The main technological development in this generation that distinguished the First Generation
mobile phones from the previous generation was the use of multiple cell sites, and the ability
to transfer calls from one site to the next site as the user travelled between cells during a
conversation.
•It uses analog signals.
•It allows the voice calls in one country.

15. •Disadvantages
•Poor quality of voice
•Poor life of Battery
•Size of phone was very large
•No security
•Capacity was limited
•Poor handoff reliability

16. 2G
•This is the second generation of mobile telecommunication was launched in Finland in 1991.
•It was based on GSM standard.
•It enables data transmission like as text messaging (SMS -Short Message Service), transfer or
photos or pictures (MMS ? Multimedia Messaging Service), but not videos.
•The later versions of this generation, which were called 2.5G using GPRS (General Packet
Radio Service) and 2.75G using EDGE (Enhanced data rates for GSM Evolution) networks.
•It provides better quality and capacity.

17. •Disadvantages
•Unable to handle complex data such as Video
•Requires strong digital signals

18. 3G
•3G is the third generation was introduced in early 2000s.
•The transmission of data was increased up to 2Mbits/s, which allows you to sending or receiving large email messages.
•The main difference between 3G and 2G is the use of packet switching rather than circuit switching for data transmission.
•Faster communication
•High speed web or more security
•Video conferencing
•3D gaming
•TV streaming, Mobile TV, phone calls etc. are the features of 3G.

19. •Disadvantages
•Costly
•Requirement of high bandwidth
•Expensive 3G phones
•Size of cell phones was very large.
•

20. 4G
•4G is the fourth generation of mobile telecommunication which was appeared in 2010.
•It was based on LTE (Long Term Evolution) and LTE advanced standards.
•Offer a range of communication services like video calling, real time language translation and video voice mail.
•It was capable of providing 100 Mbps to 1Gbps speed.
•High QoS(Quality of Service) and High security.
•The basic term used to describe 4G technology is MAGIC. Where :
M -Mobile multiedia
A -Anytime anywhere
G -Global mobility support
I -Integartedwireless solution
C -Customized personal service

21. •Disadvantages
•Uses more battery
•Difficult to implement
•Expensive equipment are required

22. 5G
•It is referedto fifth generation wireless connection which will be probably implemented by
2020, or even some years earlier.
•Machine to machine communication can be possible in 5G.
•5G will be able to performs Internet of Things (IoT) for smart home and smart city, connected
cars etc.
•This generation will be based on lower cost, low battery consumption and lower latency than
4G equipment.
•There will be much fatertransmission rate of data to the previous versions. Thus the speed of
5G will be 1Gbit/s.

24. FREQUENCY REUSE
•Frequency Reuseis the scheme in which allocation and reuse of channels throughout a coverage
region is done.
•Each cellular base station is allocated a group of radio channels or Frequency sub-bands to be
used within a small geographic area known as a cell. The shape of the cell is Hexagonal. The
process of selecting and allocating the frequency sub-bands for all of the cellular base station
within a system is calledFrequency reuseorFrequency Planning.Salient features of using
Frequency Reuse:
•Frequency reuse improve the spectral efficiency and signal Quality (QoS).
•Frequency reuse classical scheme proposed for GSM systems offers a protection against
interference.
•The number of times a frequency can be reused is depend on the tolerance capacity of the radio
channel from the nearby transmitter that is using the same frequencies.
•In Frequency Reuse scheme, total bandwidth is divided into different sub-bands that are used by
cells.
•Frequency reuse scheme allow WiMaxsystem operators to reuse the same frequencies at different
cell sites.

26. •Cell with the same letter uses the same set of channels group or frequencies
sub-band.
•To find the total number of channel allocated to a cell: S = Total number of
duplex channels available to use k = Channels allocated to each cell (k<S) N
= Total number of cells or Cluster Size Then Total number of channels (S) will
be,

27. ADVANTAGES :
•Improved Spectral Efficiency:By reusing the same frequency in different geographic
areas, spectral efficiency can be improved, enabling more efficient spectrum usage.
•Better Quality of Service:With the ability to reuse the same frequency in different
cells, the interference between cells can be minimized, leading to better quality of
service.
•Cost-Effective:Frequency reuse can reduce the cost of building a cellular network
since fewer frequency bands are required.
Scalability: Frequency reuse enables the network to be easily scaled by adding more
cells as needed.
•Increased Network Capacity:Frequency reuse allows more cells to be served with
the same amount of spectrum, resulting in increased network capacity.
•Scalability:Frequency reuse enables the network to be easily scaled by adding
more cells as needed.

28. DISADVANTAGES:
•Increased Interference:Frequency reuse can result in increased interference, particularly in areas where cells
are closely spaced. This can reduce the quality of service and network capacity.
•Implementation Complexity: Frequency reuse requires careful planning to ensure that cells are appropriately
spaced and that interference is minimized. This can make the implementation process more complex and time-
consuming.
•Reduced Coverage:With the use of smaller cells to achieve higher capacity, the coverage area of each cell is
reduced, requiring more base stations and infrastructure.
•Increased Power Consumption:Due to the use of smaller cells, more base stations are required, leading to
higher power consumption and operational costs.
•Increased Network Cost:The cost of implementing a frequency reuse system may be higher due to the need
for additional infrastructure and careful planning to ensure proper frequency reuse.

29. CHANNEL ASSIGNMENT STRATEGIES
•Channel Assignment strategies means to allocate the available channels to the
cells in a cellular system Whenever a user wants to make a call request then
by using channel assignment strategies their requests are fulfilled.
•Channel Assignment Strategies are designed in such a way that there is
efficient use of frequencies, time slots and bandwidth.

30. •There are three types of Channel Assignment Strategies they are: Fixed,
Dynamic, and Hybrid Channel Assignment.

31. FIXED CHANNEL ASSIGNMENT (FCA):
•It is a strategy in which fixed number of channels or voice channels are allocated to
the cells.
•Once the channels are allocated to the specific cells then they cannot be changed.
•Fixed channel assignment are very simple and requires least amount of processing.
•Cells in this strategy are allowed to borrow channels from adjacent cells if their
channels are fully occupied while adjacent cells have free channels.
•No interference occurs by moving the channel from one cell to another.

32. In cell A 20 Channels or Voice channels are allocated. If all channels are occupied and
user make a call then the call is blocked.Borrowing Channelshandles this type of
problem. This cell borrow channels from other cells.

33. •Advantages :
•Simple to implement and manage
•Does not require complex equipment or algorithms
•Disadvantages :
•Limited channel utilization as unused channels remain unused.
•Susceptible to interference and congestion.

34. DYNAMIC CHANNEL ASSIGNMENT (DCA):
•Dynamic Channel Assignment is a strategy in which channels are not permanently
allocated to the cells.
•When a User makes a call request then Base Station send that request to the MSC
(Mobile Station Cente) for the allocation of channels or voice channels.
•Each time a call request is made, serving BS requests a channel from the MSC.
•MSC assigns a channel only if it is not used and if it will not cause co‐channel
interference with any cell in range. In this MSC has to collect real time data on
channel occupancy, traffic distribution, radio signal strength indication of all channels
on continuous basis, thus increasing the computational load on MSC.

35. •Advantages :
•Efficient use of available bandwidth.
•Reduces call blocking and improves call quality.
•Allows for dynamic allocation of resources.
•Disadvantages :
•Requires more complex equipment and algorithms.
•May result in call drops or poor quality if resources are not available

36. HYBRID CHANNEL ASSIGNMENT (HCA):
•Hybrid Channel Allocation is a combination of both Fixed Channel Allocation
(FCA) and Dynamic Channel Allocation (DCA). In this total number of channels
or voice channels are divided into fixed and dynamic sets. If a user make a
call then first fixed set of channels are utilized but if all the fixed sets are
busy then dynamic sets are used. The main purpose of HCA is to work
efficiently under heavy traffic

37. •Advantages :
• Provides the benefits of both FCA and DCA.
• Allows for dynamic allocation of resources while maintaining predictable call
quality and reliability.
•Disadvantages :
•Requires more complex equipment and algorithms than FCA.
•May not provide the same level of efficiency as pure DCA.

38. BORROWING CHANNEL ALLOCATION (BCA):
•when a cell experiences high traffic demand and all of its channels are
occupied, it can borrow channels from neighboring cells that are not being
used at that time. The borrowed channels are assigned to the busy cell and
are used to support the additional traffic demand. Once the demand
subsides, the borrowed channels are released and returned to their home cell.
BCA can be implemented manually or automatically using algorithms or
policies but the main disadvantage is that if the borrowed channel is
reclaimed by the original cell the call drop may occur.

39. •Advantages :
•Efficient use of available bandwidth.
•Reduces call blocking and improves call quality.
•Disadvantages :
•Increases interference between cells.
•Can cause call drops if borrowed channels are reclaimed by the home cell.

40. INTERFERENCE AND SYSTEM CAPACITY
•Interference is the major limiting factor in the performance of cellular radio systems.
•Sources of interference:
There are two types of sources of interference:
a. Active
b. Passive

41. •a. Active
Active interference sources that emits a radio signals on the same frequency.
•1. another mobile in the same cell.
•2. a call in progress in a neighboring cell.
•3. other base stations operating in the same frequency band, or any noncellular system which inadvertentlyleaks energy into
the cellular frequency band.
•b. Passive
•Passive source of wireless interference is any substance that restricts to degrade a wireless signal that attempt to pass
through it.
•Examples of such substances are metal, concrete, paper, fabric, glass, stone wood, bricks, etc..

42. PROBLEMS BECAUSE OF INTERFERENCE:
•1. Interference on voice channels causes cross talk, where the subscriber hears
interference in the background due to an undesired transmission.
•s2. On control channels, interference leads to missed and blocked calls due to errors
in the digital signaling.
Interference is more severe in urban areas, due to the greater RF noise floor and the
large number of base stations and mobiles. Interference has been recognized as a
major bottleneck in increasing capacity and is often responsible for dropped calls.

43. Power Control for Reducing Interference
Introduction:
To ensure each mobile transmits the smallest power necessary
to maintain a good quality link on the reverse channel. Power Control
for Reducing Interference becomes very important.

44. POWER CONTROL:
•In practical cellular radio and personal communication systems the power levels
transmitted by every subscriber unit are under constant control by the serving base
stations.
•This is done to ensure that each mobile transmits the smallest power necessary to
maintain a good quality link on the reverse channel.
•Power control not only helps prolong battery life for the subscriber unit, but also
dramatically reduces the reverse channel S/I in the system.
•Power control on the downlink has less impact on intercell interference than on the uplink,
since the downlink transmissions all originate from the cell center, whereas uplink
transmissions can come from the cell boundaries, which exacerbates interference to
neighboring cells.
•Thus we will focus on the effect of power control on the uplink. Consider the two cells
shown in Figure 5.7. Suppose that both mobiles B1 and B2 in cell B transmit at the same
power.

45. •Then the interference caused by the mobile B1 to the base station in cell A
will be relatively large, since it is close to the boundary of cell A, while the
interference from B2 will generally be much weaker due to the longer
propagation distance.
•If water-filling power adaptation is employed, then B1 will generally transmit
at a lower power than B2, since it will typically have a worse channel gain than
B2 to the base station in cell B as it is farther away.
•This has the positive effect of reducing the intercell interference to cell A. In
other words, water filling power adaptation reduces intercell interference from
mobiles near cell boundaries, the primary source of this interference.
•A similar phenomenon happens with multiuser diversity, since users transmit
only when they have a high channel gain to their base station, which is
generally true when they are close to their cell center.
•Conversely, under channel inversion the boundary mobiles will transmit at a
higher power to maintain the same received power at the base station as
mobiles near the cell center.
•This has the effect of increasing intercell interference from boundary mobiles.