MN603 Wireless Networks And Security

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Question:

Tasks

1.Different technologies of Wireless LAN, such as IEEE 8021.1a, 8021.1b, 8021.1g, and 8021.1n.

You should research each of the 4 WLAN technologies thoroughly and pay particular attention to how they are used, as well as their strengths and weaknesses.

Comment on which WLAN 802.11 standard is going to be the dominant player in the future

2. Compare and contrast FHSS and DSSS wireless networking areas?

3.A local engineering organization asks you to give your findings about different antenna types used in wireless technologies.

Study 4 different antenna types in detail. Pay attention to how they are used and their strengths and weaknesses.

Please share your opinion about which antenna types will be the dominant in the future.

Your answer should include power point slides.

Answer:

There are several types of WLAN technologies.

The following paragraph will cover four technologies.

These technologies are 802.11a (b), 802.11b (g), and 802.11n (n).

802.11a was the first type standard in 802.11.

802.11a is the first type of standard in 802.11.

But the chips can be expensive.

It has a high level of performance (Siddiqui Zeadally & Salah (2015)).

802.11a can provide a good range, but only when it is running at its maximum data rate. This limit is set by the standard.

It is licensed free and can be used anywhere in the world.

802.11a also has subcarriers. These are QPSK (BPSK), QPSK (16-QAM) and 64QAM (64-QAM).

Orthogonal Frequency Division Multiplex (OFDM), while difficult to use in 802.11a offers the benefit of reducing interference issues due to multipath.

802.11b has been widely adopted and used in laptops and other equipments. It operates at 2.4 GHz (Dalal et. al., 2014.).

It offers a higher data rate that 802.11b and has data rates as high as 11 Mbps.

802.11b uses CSMA/CA to transmit data.

It transmits clear channels, and retransmits it if it does not receive acknowledgement from the receiver.

802.11b uses Complementary Code Keying.

This signal is simpler to upgrade the chipset, and so it is more readily available on the market.

However, it has one disadvantage: if the signal falls between the interference or is higher, the system will use slower data rates with some errors.

802.11g was the predecessor of 802.11b. It operates in the 2.4 GHz ISM Band (Ermakov et. al., 2014).

Maximum data rate is 54 Mbit/s

It is not compatible with 802.11b. This causes a decrease in speed.

The four layers of 802.11g are: ERP-DSSS–CCK, ERP–OFDM/PBCC, ERP–DSSS/PBCC, and DSSS–OFDM.

It rarely experiences interference with the signal.

It is composed of Preamble/Header as well as Payload.

Preamble then transmits Payload which is the actual data.

However, it has a limitation. The overall decoding process cannot be completed in the given time. 16 us is still needed (Clerckx&Oestges (2013)).

To achieve this performance, a signal extension is applied of 6 us.

802.11n is the newest standard in 802.11 and offers a much faster speed than other standards.

It works with 802.11b/802.11g.

It can adapt to changing speeds and maintain its performance.

Some innovations add complexity to the system. These innovations are implemented in high-performance mode to ensure maximum performance.

802.11n has advantages in three modes: legacy mode, mixed and greenfield mode.

It is ideal for large networks but not small networks.

802.11n will continue to be a dominant player due to its features which are continuously updated.

It has a higher data rate than 802.1a or 802.11b.

It can provide up to 4*4*4 data streams, which significantly improves data flow.

There are several advantages to this technology, including increased bandwidth, power conservation and antenna technology.

It is best for large networks but not for smaller networks.

2.Comparation of FHSS & DSSS

Direct Sequence Spread Spectrum and Frequency Hopping Spread Spectrum are the two types of frequency hopping spread spectrum (FHSS).

Frequency hopping Spread Spectrum uses frequency hopping. It is achieved through the division of large bandwidths to fit the data. The division is made in small channels (Alatabani & Abdalla (2015)).

Direct Sequence Spread Spectrum however uses pseudo noise to introduce signals and the phase can be altered due to this.

FHSS is ideal for large coverage installations and multiple collocated cells.

DSSS can’t be used if the collocated cells are overlapped.

DSSS is possible if the collocated cell are not overlapped. DSSS will also require directional antennas for use with collocate cells.

FHSS has a Signal to Noise Ratio(SNR) of 18 dB and DSSS has a Phase-shift Keying (PSK), of 12 dB.

FHSS can operate at greater distances than DSSS. However, DSSS operations have lower SNR (Hasan Thakur & Podder (2014)).

FHSS’ interference level is lower than DSSS’s because spectrum is 83.5 MHz and DSSS has 22 MHz.

FHSS and DSSS have the same issue with foreign transmitters. The difference is that FHSS signals won’t be heard, while DSSS signals will be heard.

FHSS is more efficient than DSSS.

Multipath issue in DSSS is more sensitive than FHSS.

Overall, DSSS has a higher capacity than FHSS, but FHSS offers more strength.

Two types of antennas are used in wireless network: Omni-directional or directional.

Omni-directional antennas can be used in 360 degree patterns, while directional antennas work only in one direction.

There are four types available for directional antennas. They are Yagi Dish, Sector, Grid and Grid (Khan Riaz & Bial, 2016).

Four types of Omni-directional antennas exist: Spider Omnidirectional antennas, Rubber duck antennas, ceiling mount Omnidirectional antennas, outdoor Omnidirectional, and ceiling mount Omnidirectional.

In the following paragraphs, we’ll discuss directional antennas.

Most commonly, yagi is used as an antenna in old television sets.

It can have multiple parallel lines.

It is used for high frequency frequencies (Bandyopadhyay Roy and Ueda (2016)

It can be used to communicate short to medium distances as well as point-to–point.

It is located outdoors.

It can be used to reach multiple frequencies, and is most commonly used for long distance applications.

Dish is another type.

It is commonly known as dish network, and it can be used as a parabolic reflector.

It is extremely directive.

Parabolic antennas can be used to direct radio waves at the narrowest possible form. The radio wave is only received in one direction.

It is commonly used for high frequency, sound and television.

Due to its large surface area, it is capable of collecting a lot of signals.

Sector antenna is a type or directional antenna that directs its beam in an extended shape.

It has a 30 degree to 120 degree range, which allows it operate in hemispheres (Rumsey 2014).

It is most commonly used to power base operations, such as cell phones, at station sites.

Grid antennas, a type directional antenna, have similar structures to dish antennas.

Grid antennas are equipped with a reflector, which is made of grid and can withstand severe wind conditions.

The frequency of the grid’s spaces is dependent on their frequency.

It’s used for long-distance transmissions over wifi.

Omni-directional antennas have 360 degrees coverage.

They are most commonly used within the office.

Because they have 360-degree coverage, these antennas can be used for walki-talkies or mobile devices.

Rubber Duck Antenna can be used as a router.

Spider Omni-directional Antennas are simple in design. They use a standard N-type connector. (Rusch & Potter (2013)

The ceiling mount Omni-directional Antennas are mounted on the ceiling, which is a benefit.

Outdoor Omni-directional Antennas also known by GP are weatherproof and waterproof.

A directional antenna can be used indoors for specific applications.

Directional antennas work well for long distances and are ideal for both point-to–point and point–to–multipoint links.

It reduces interferences caused by multiple unwanted signals.

Directional antennas can provide a better link quality to any network.

As they only operate in one direction, directions antennas will dominate the future.

Different types can be used to achieve different purposes.

Grid or Yagi will be required to connect two buildings.

Omni-directional antennas, however, are more suitable for use inside an office because they provide greater frequency range in small networks and have 360 degrees wireless coverage in small networks.

Only directional antennas can be used in an office environment or for industrial purposes.

Refer to

FHSS and DSSS Performance Evaluations for VSAT.

INTERNATIONAL JOINAL OF SCIENTIFIC & TECHNOLOGY RESEARCH. 4(09).

Smart antennas improve performance in ad-hoc wireless networks.

CRC Press.

MIMO wireless networks – Channels, techniques, and standards for multiantenna, multiple-user, and multi-cell systems.

Academic Press.

TCP Performance in IEEE 802.11 Wireless Networks: Link Layer Correction Techniques and Their Impact.

Communications and Network 6(2): 49.

Optimization of expert techniques used to analyze information security risk within modern wireless networks.

Life Sciences Journal 23, 1239.

Design and implementation of FHSS/DSSS for Secure Data Transmission.

International Journal of Signal Processing Systems.

A review on the Different Types of Antennas with Respect to their Applications:

International Journal of Multidisciplinary sciences and Engineering 7(3).

Frequency independent antennas.

Academic Press.

Analyse reflector antennas.

Academic Press.

Gigabit wireless networking with IEEE 802.11 ac – Technical overview and challenges.

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