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MOBILE COMPUTING IN DISTRIBUTED SYSTEM. Group Members: Shafinah KamarudinGS14607 Eizaireen Erma RamseGS14614 Fadzlina Mohammad AzmiGS14671 Siti Haslia Yaakob GS14710 Masliza Mhd. Ali ShahGS15374. MOBILE COMPUTING.

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MOBILE COMPUTING IN DISTRIBUTED SYSTEM

Group Members:

Shafinah KamarudinGS14607

Eizaireen Erma RamseGS14614

Fadzlina Mohammad AzmiGS14671

Siti Haslia Yaakob GS14710

Masliza Mhd. Ali ShahGS15374


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MOBILE COMPUTING

  • Mobile Computing, also known as ubiquitous computing and nomadic computing is an umbrella term used to describe technologies that enable people to access network services anyplace, anytime, and anywhere.

  • Mobile Computing systems can be viewed as a specialized class DS where some nodes can disengage from joint distributed operations, move freely in the physical space and reconnect to a possibly different segment of a computer network at a later stage in order to resume suspended activities.


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WHAT IS Wi-Fi?

  • Short for wireless fidelity, WiFi is the leading communication protocol for wireless local area networks (WLANs). .

  • Formerly, the term "Wi-Fi" was used only in place of the 2.4GHz 802.11b standard. The Alliance expanded the generic use of the term in an attempt to stop confusion about WLAN interoperability.

  • WiFi generically refers to any type of 802.11 network, whether 802.11b, 802.11a, 802.11g, or a dual-band combination of these IEEE protocols


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ADVANTAGES OF Wi-Fi

  • Unlike packet radio systems, Wi-Fi uses unlicensed radio spectrum and does not require regulatory approval for individual deployers.

  • Allows LANs to be deployed without cabling, potentially reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

  • Wi-Fi products are widely available in the market. Different brands of access points and client network interfaces are interoperable at a basic level of service.

  • Competition amongst vendors has lowered prices considerably since their inception.


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  • Many Wi-Fi networks support roaming, in which a mobile client station such as a laptop computer can move from one access point to another as the user moves around a building or area.

  • Many access points and network interfaces support various degrees of encryption to protect traffic from interception.

  • Easy to add on to an existing Ethernet network.

  • Easy to expand the number of users and OS.

  • Good operating range – 75 to 300 yards, depending on conditions.

  • Mix or match. Wi-Fi h/w interchangeable with other Wi-Fi h/w.

  • Different h/w platform – common medium of exchange.

  • Safety – output power of Wi-Fi equipment is much lower than cellular phone. Max output 1 watt of transmit power and send data in short bursts. So, nasty health effects.


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DISADVANTAGES OF Wi-Fi

  • Use of the 2.4 GHz Wi-Fi band does not require a license in most of the world provided that one stays below the 100mWatt limit and one accepts interference from other; including interference which causes your devices to no longer function.

  • Legislation is not consistent worldwide; most of Europe allows for an additional 2 channels; Japan has one more on top of that - and some countries, like Spain, prohibit use of the lower-numbered channels.

  • Power consumption is fairly high compared to other standards, making battery life and heat a concern.


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  • The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum, which is crowded with other devices such as Bluetooth, microwave ovens, cordless phones (900 MHz or 5.8 GHz are, therefore, alternative phone frequencies one can use if one has a Wi-Fi network), or video sender devices, among many others. This may cause a degradation in performance. Other devices which use microwave frequencies such as certain types of cell phones can also cause degradation in performance.

  • Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g might have a range of 150 ft (46 m) indoors and 300 ft (92 m) outdoors.


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  • The most common wireless encryption standard, Wired Equivalent Privacy or WEP, has been shown to be easily breakable even when correctly configured. Although newer wireless products are slowly providing support for the Wi-Fi Protected Access (WPA) protocol, many older access points will have to be replaced to support it.

  • The adoption of the 802.11i (aka WPA2) standard in June 2004 makes available a rather better security scheme for future use — when properly configured. In the meantime, many enterprises have had to deploy additional layers of encryption (such as VPNs) to protect against interception.

  • Rogue access points could be used to steal information transmitted from Wi-Fi users.


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WIRELESS LAN AND IEEE 802.11

A wireless LAN (WLAN) is a data transmission system designed to provide location-independent network access between computing devices by using radio waves rather than a cable infrastructure. In the corporate enterprise, wireless LANs are usually implemented as the final link between the existing wired network and a group of client computers, giving these users wireless access to the full resources and services of the corporate network across a building or campus setting.


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.

  • The major motivation and benefit from wireless LANs is increased mobility. Network users can move about almost without restriction and access LANs from nearly anywhere.

  • The 802.11 specification as a standard for wireless LANS was ratified by the Institute of Electrical and Electronics Engineers (IEEE) in the year 1997. This version of 802.11 provides for 1 Mbps and 2 Mbps data rates and a set of fundamental signaling methods and other services. Like all IEEE 802 standards, the 802.11 standards focus on the bottom two levels the ISO model, the physical layer and link layer .


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802.11 STANDARD IN OSI MODEL


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IEEE WIRELESS

STANDARDS

  • The most critical issue affecting WLAN demand has been limited throughput. The data rates supported by the original 802.11 standard are too slow to support most general business requirements and slowed the adoption of WLANs.

  • Recognizing the critical need to support higher data-transmission rates, the IEEE ratified the 802.11b standard (also known as 802.11 High Rate) for transmissions of up to 11 Mbps.

  • After 802.11b one more standard 802.11a has been ratified and in January 2002 the draft specification of another 802.11g has been approved.


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IEEE 802.11b STANDARD

  • With 802.11b WLANs, mobile users can get Ethernet levels of performance, throughput, and availability. The basic architecture, features, and services of 802.11b are defined by the original 802.11 standard. The 802.11b specification affects only the physical layer, adding higher data rates and more robust connectivity.

  • The key contribution of the 802.11b addition to the wireless LAN standard was to standardize the physical layer support of two new speeds,5.5 Mbps and 11 Mbps.

  • Nowadays, most widely use IEEE 802.11b standard.


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  • More prone to interference than 802.11a, but lower frequency gives longer range, estimated at between 75 to 300 meters.

  • Faster at 54Mbps and less vulnerable to radio noise.

  • Greater capacity – wireless streaming video

  • Significant disadvantage of 802.11b is that the frequency band is crowded, and subject to interference from other networking technologies, microwave ovens, 2.4GHz cordless phones, and Bluetooth.

  • Other drawbacks including lack of interoperability with voice devices, and no QoS provisions for multimedia content.

  • Interference and other limitations aside, 802.11b is the clear leader in business and institutional wireless networking and is gaining share for home applications as well.


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IEEE 802.11a STANDARD

  • All wireless LANs use unlicensed spectrum; therefore they're prone to interference and transmission errors. To reduce errors, both types of 802.11 automatically reduce the Physical layer data rate. IEEE 802.11b has three lower data rates (5.5, 2, and 1Mbit/sec), and 802.11a has seven (48, 36, 24, 18, 12, 9, and 6Mbits/sec). Higher (and more) data rates aren't 802.11a's only advantage.

  • It also uses a higher frequency band, 5GHz, which is both wider and less crowded than the 2.4GHz band that 802.11b shares with cordless phones, microwave ovens, and Bluetooth devices.


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  • Also used a modulation scheme – Orthogonal Frequency Division Multiplexing (OFDM), makes possible data speed as high as 54Mbps and cut down on cross-channel and reflected-signal interference.

  • One big disadvantage is that it is not directly compatible with 802.11b, and requires new bridging products that can support both types of networks. Other clear disadvantages are that 802.11a is only available in half the bandwidth in Japan (for a maximum of four channels), and it isn't approved for use in Europe, where HiperLAN2 is the standard.


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IEEE 802.11g STANDARD

  • Though 5GHz has many advantages, it also has problems and one of them is compatibility. The different frequencies mean that 802.11a products aren't interoperable with the 802.11b base.

  • To get around this, the IEEE developed 802.11g, which should extend the speed and range of 802.11b so that it's fully compatible with the older systems.

  • The obvious advantage of 802.11g is that it maintains compatibility with 802.11b (and 802.11b's worldwide acceptance) and also offers faster data rates comparable to 802.11a.

  • Disadvantage of 802.11g is that it also works in the 2.4 GHz band and so due to interference it will never be as fast as 802.11a.


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Wireless standards and their networking environment


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802.11 in Malaysia

  • Recently started employing the 802.11g standard replacing 802.11b.

  • Market place is very competitive since:

    • Wi-Fi usage is still in its infancy.

    • Providers do not need special license to provide Wi-Fi services as long as Internet access is supplied by licensed Internet Access Service Providers.


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According to IDC Malaysia – 480 hotspots with 12,000 subscribers as of Dec 03.

Figure is expected to increase by 58% throughout 2004 – 2008 reaching 120,000 subscribers.

Among some Wi-Fi providers are:

TMNet

TIME

Celcom

Maxis

802.11 in Malaysia (cont.)

  • Jaring

  • Airzed Network

  • Gold Information Systems


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INTRODUCTION OF WiMAX

  • The term WiMAX stand for ‘Wireless Interoperability for Microwave Access.

  • Technology that involves microwaves for the transfer of data wirelessly.

  • Can be used for high-speed, wireless networking distances up to a few miles up to 30 miles.

  • It is similar to Wi-Fi that use the same core technology of wireless modulation developed way back in 60’s and 70’s.

  • Also known as OFDM (Orthogonal Frequency Division Multiplexing)

  • Use IEEE 802.16 standard addresses frequencies from 10GHz to 66GHz.


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INTRODUCTION OF WiMAX (Cont.)

  • Can run signals very close to each other on wireless channels.

  • Can super narrow lanes, can put a lot of traffic over them and they don’t disrupt each other

  • Channel sizes range from 1.5 to 20 MHz.

  • Supports ATM, IPv4, IPv6, Ethernet, and VLAN services.

  • Provide a rich choice of service possibilities to voice and data network providers.


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BENEFIT OF WiMAX TECHNOLOGY

  • Cost effective

  • Ability to get higher connection speeds farther away from the transmitter

  • Much easier to install – enable self installation

  • More scalable and multi-access capabilities to the fixed OFDM technology.

  • Other advantages – robust security features, good QoS and mesh and smart antenna technology that will allow better utilization of the spectrum resources.


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The WiMAX Wireless Architecture


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Wi-Fi vs WiMAX

  • How Do Wi-Fi and WiMAX Relate? Wi-Fi and WiMAX are actually complementary technologies.

  • As WiMAX is a "last mile" technology, meaning that it connects businesses and homes to the high-speed Internet.

  • Wi-Fi provides the wireless LAN connectivity within a building or a home. In the notebook computer of the future, we may have both WiMAX and Wi-Fi technology to make connections to the broadband Internet. These two technologies have been architected as close cousins, and will work together to provide the best connection for user needs.


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1G

  • Short for 1st generation mobile technology.


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2G

  • Short for 2nd generation mobile technology.


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2.5G / 2.75G

  • Stepping stone between 2G and 3G cellular wireless technologies.

  • Are not officially defined; invented for marketing purposes.


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2.5G / 2.75G (cont.)

  • Some protocols, such as EDGE and CDMA2000 1x-RTT, officially qualify as 3G services (because they have a data rate of above 144kbps), but are considered by most to be 2.5G or 2.75G services because they are several times slower than "true" 3G services.


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3G

  • Short for 3rd generation mobile technology.

  • Refers to pending improvements in wireless data and voice communications through any of a variety of proposed standards.

  • Immediate goal – to raise transmission speeds from 9.5K to 2M bps.


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3G (cont.)


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3G: System Capabilities

  • Capability to support circuit and packet data at high bit rates:

    • 144 Kbps or higher in high mobility (vehicular) traffic.

    • 384 Kbps for pedestrian traffic.

    • 2 Mbps or higher for indoor traffic.

  • Interoperability and worldwide roaming capability


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3G: System Capabilities (cont.)

  • Common billing/user profiles:

    • Sharing of usage/rate information between service providers.

    • Standardized call detail recording.

    • Standardized user profiles.

  • Capability to determine geographic position of mobiles and report it to both the network and the mobile terminal.


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3G: System Capabilities (cont.)

  • Support of multimedia services/capabilities:

    • Fixed and variable rate bit traffic Bandwidth on demand.

    • Asymmetric data rates in the forward and reverse links.

    • Multimedia mail store and forward.

    • Broadband access up to 2 Mbps.


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3G in Malaysia

  • Malaysia – still relatively new.

  • based on W-CDMA standard, similar to the system used by European countries.

  • licences awarded to:

    • Telekom Malaysia Bhd. (July 02)

    • Maxis Communications Bhd. (July 02)

    • DiGi Telecommunication Sdn. Bhd. (Nov 04)


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3G in Malaysia (cont.)

  • July 03 – 14 Jan 04: TM conducted pilot testing.

  • Jan – Dec 04: 300 TM customers were introduced to subscribe to a limited set of 3G services provided in various parts of the MSC and Klang Valley.

  • 2005: TM (through Celcom) and Maxis are set to fully launch their 3G services in major cities first.


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4G

  • Short for 4th generation mobile technology.

  • Still undergoing a lot of research and development processes.

  • Key players – Japan, Korea, China, Europe.

  • ITU’s 4G definition:

    • 1Gbps standstill

    • 100Mbps when moving at train-like speeds


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4G (cont.)

  • June 2004 – Japan’s NTT DoCoMo revealed results from new 4G test system:

    • peak – 300 Mbps

    • average rate – 135Mbps

      in a car moving at 30kmph; at a distance of 800m to 1km from base stations.


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Comparison: 3G - 4G


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Conclusion

  • Mobile data communication has become a very important and rapidly evolving technology as it allows users to transmit data from remote locations to other remote or fixed locations.

  • This proves to be the solution to the biggest problem of business people on the move – mobility.

  • With current developments and upcoming technologies, mobility will no longer be a big issue.


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