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High Speed Cellular Technologies Over The Internet


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  • 1. High Speed Cellular Technologies over the Internet Guide : Prof. A. Sahoo
  • 2. Outline
    • Introduction to 1G and 2G Technologies.
      • GSM & CDMA.
    • 2.5G Technologies.
      • GPRS & EDGE .
    • 3G Technologies.
      • W-CDMA (UMTS), HSDPA & MBMS.
    • 4G Technologies.
      • LTE, UMB & WIMAX .
  • 3. 1G Technologies
    • Analog cellphone standard introduced in 1980.
    • Radio signal used were analog.
      • voice during a call is modulated to high frequency 150 MHz.
    • AMPS (Advanced mobile phone systems)
      • Based on FDMA.
      • Developed by Bell Labs and deployed in US in 1983.
      • No longer exists in the market.
  • 4. 2G Technologies
    • GSM.
      • Global System for Mobile communications.
      • Digital cellphone standard.
      • Operate in the 900 MHz or 1800 MHz bands.
      • Based on TDMA.
      • Generally offer data rates of 9.6 kbps.
      • Splits the frequency band into multiple channels and increases each channel bandwidth by dividing it into multiple time slots.
      • Modulation based on GMSK a variant of FSK.
  • 5. GSM Architecture Source :
  • 6. GMSK
    • In FSK the digital information is transmitted through discrete frequency changes of a carrier wave.
    • MSK is spectrally efficient form of FSK.
    • In MSK the difference between the higher and lower frequency is identical to half the bit rate. As a result, the waveforms used to represent a 0 and a 1 bit differ by exactly half a carrier period.
    • In GMSK the digital data stream is first shaped with a Gaussian filter.
  • 7. 2G Technologies
    • CDMA.
      • Code Division Multiple Access.
      • Data rates are 14.4Kbps to 115K bps.
      • Assign codes to seperate transmission which can then run at the same time on a single channel spread across a wide range of radio frequencies.
      • Each receiver decodes only the transmission it is supposed to work with.
      • CDMA permits several radios to share the same frequencies.
  • 8. 2.5G Technologies
    • Motivation
      • 2G Technologies are Circuit Switched in which bandwidth remains idle ample amount of time during communication.
      • Why not use this idle time to transfer packets.
      • Transfering Packets is Cheaper.
    • Use Existing infrastructure while adding some additional node which provide packet functionality to the network
    • Evolved During the transition of TDMA based 2G systems to 3G systems.
  • 9. 2.5G Technologies
    • Advantages
      • Provides data rate comparable to 3G.
      • Work on the same spectrum allocated to 2G.
      • provide an opporunity to players to compete who do not want to invest heavily in 3G.
      • GPRS & EDGE are the main drivers.
  • 10.
    • General Packet Radio Service.
    • GSM Infrastructure Enhancement.
    • Packet-oriented Data Service.
    • Allows IP packets to be sent and received across mobile networks.
    • Theoretical maximum speed: 171.2 kbps using all 8 time slots.
    • Developed for optimum usage of radio resource which is scrace.
    • Small step compared to building a totally new 3G IMT-2000 network.
  • 11. GPRS continued
    • Users will pay for actual data transmitted not for the connection time.
    • No change in air interface & modulation scheme this is also a limitation for even higher data rate.
    • Base Station Subsystem consist of Base Station Controller (BSC) & Packet Control Unit (PCU).
    • PCU support all GPRS protocols for communication over the air interface.
    • Introduced two new nodes SGSN & GGSN and HLR is enhanced with GPRS subscriber data and routing information.
  • 12. Source : WS 03/04, TKN TU Berlin, Cornelia Kappler
  • 13. EDGE
    • Enhanced data rates for GSM evolution.
    • GSM/GPRS-Network Enhancementr
    • Datarate compareable to UMTS Network (384 kBit/s and more).
    • Changing GSM Modulation from GMSK to 8PSK.
    • 16-QAM was also proposed for EDGE.
    • EDGE provide both PS & CS services.
    • QoS profile is defined for each sevice with QoS parameters include priority, reliability & delay.
  • 14. EDGE continued...
    • Link adaptation scheme is EDGE regularly estimate the link quality and select the appropriate modulation and coding scheme to maximize the user bit rate.
    • Incremental redundancy is also used.
    • RLC/MAC layer of GPRS need to be modified to accomodate features for multiplexing & link adaptation.
  • 15. PSK
    • Phase shift keying is a digital modulation scheme that conveys data by modulating the phase of the carrier wave.
    • PSK uses a finite number of phases, each assigned a unique pattern of binary bits (symbol).
    • The demodulator determines the phase of the received signal and maps it back to the symbol.
    • BPSK uses 2 phases to transmit data (0's and 1's).
      • Able to transmit 1 bit per symbol.
    • QPSK (4-PSK) uses 4 phases to transmit data thus forming 4 symbols (00,01,10,11).
    • 8-PSK uses eight phases forming 8 symbols and is the highest order PSK constellation
      • Able to transmit 3 bit per symbol.
  • 16. 8-PSK Source :
  • 17. Why 2.5G Provides Higher Data Rate
    • Packet data capabilities are added in GPRS.
    • Some additional nodes are added in architecture to facilitate IP functionality.
    • In EDGE the modulation scheme is changed to 8-PSK while GSM uses GMSK.
    • GSM uses GMSK modulation that can send 1 bit per symbol while EDGE uses 8-PSK which transmits 3 bits per symbol.
  • 18. 3G Technologies
    • Based on ITU standard IMT-2000
    • 3G capabilities mainly means supporting higher bit rates.
    • 3G capabilities implies the addition of
      • Packet Switched Services.
      • internet Access & IP Connectivity.
    • Provide service at 2 Mbps for stationary users and 384 Kbps for mobile users.
    • 3G standards are W-CDMA (UMTS) and CDMA-2000.
  • 19. IMT - 2000
    • International Mobile Telecommunications.
    • Operates at the frequency of 2000 Mhz.
    • Bandwidth upto 2000 Mbps.
    • Basic services of IMT-2000 network
      • High-quality voice transmission.
      • Messaging (e-mail, fax, sms, chat).
      • Multimedia (playing music, videos).
      • Internet access (surfing).
  • 20. UMTS
    • Universal Mobile Telecommunications System.
    • UTRAN - UMTS Terrestrial Radio Access Network.
    • UMTS system uses the same core network as the GPRS and uses entirely new radio interface UTRAN.
    • UMTS Multiplexing
      • Wideband CDMA for air interface.
    • Up/Downlink Frequency
      • Uplink: 1920 – 1980MHz.
      • Downlink: 2110 - 2170MHz.
    • The UE is connected to Node-B over high speed Uu (up to 2 Mbps) Interface.
  • 21. UMTS Architecture Source :
  • 22. UMTS Interfaces
      • The Core Network of UMTS is same as that of GPRS. The air interface is totally different.
      • Uu: UE to Node B (UTRA, the UMTS W-CDMA air interface.
      • Iu: RNC to GSM Phase 2+ CN interface (MSC/VLR or SGSN)‏
        • Iu-CS for circuit-switched data.
        • Iu-PS for packet-switched data.
      • Iub: RNC to Node B interface.
      • Iur: RNC to RNC interface, not comparable to any interface in GSM.
  • 23. UTRAN
      • The UTRAN is the new Radio interface of UMTS. Its constituting element are RNC, Node-B and UE.
      • RNC
        • The RNCs enables autonomous radio resource management (RRM) by UTRAN.
        • RNCs also assist in Soft Handover of the UEs.
      • Node B
        • The Node-B is physical unit of radio transmission /reception with cells.
        • It connects to UE via Uu W-CDMA radio interface and RNC via Iub ATM interface.
        • The main task of Node B is forward error correction (FEC), rate adaptation, W-CDMA spreading /despreading, and quadrature phase shift keying (QPSK) modulation on the air interface.
  • 24. W-CDMA
    • W-CDMA is the air interface of UMTS.
    • W-CDMA is coming from GSM side
    • Is a part of 3GPP and used in UMTS systems.
    • Utilizes the direct sequence Code Division Multiple Access signalling method to achieve higher speeds and support more users
    • Radio channels are 5MHz wide..
    • Release 5 came out in 2002 introduced improved support for downlink packet data (HSPDA).
    • Release 6 in 05 impoved packet capabilities in Uplink MBMS.
  • 25. Why 3G Provides Higher Data Rate than 2.5G
    • New radio interface UTRAN is added which connects to the CN via lu interface.
    • Introduction of IP based multimedia service in the core network.
  • 26. 4G Technologies
    • ITU-R will release the requirements of 4G in 2008.
    • Could go beyond the cell phone and provide mobile data services to consumer electronics & other devices.
    • Example are sending of photos from camera to printer.
    • All 4G technologies will be IP-based & packet-switched.
    • Spectrally efficient modulation schemes have been developed but they wont work with existing 3G as it requires recievers to work with more complex technology Example 64 QAM.
    • The 4G Technology would enable IP-based voice, data and streaming multimedia theoretically at the speed of 288 Mbps.
  • 27. 4G continued....
    • Motivation
      • The continuing growth of wireless usage.
      • Rise of household broadband internet subscription.
      • Users want wireless technolgy that approximate the experience they have at home.
      • Demand for better quality faster video viewing and quicker downloading even for mobile users with handheld devices.
  • 28. 4G continued....
    • According to ITU recomendations 4G should provide data rates of at least 100 Mbps and use OFDMA a multiuser version of OFDM.
    • OFDM increases bandwidth by splitting data-bearing radio signal into smaller signal sets and modulating each onto a different subcarrier, transmitting them simultaneously at different frequencies.
    • The subcarriers are spaced orthogonally.
    • 64 QAM is higher order modulation scheme in which each transmitted unit conveys 6 data bits compared to 16 QAM 4 and 8-PSK 3 bits.
  • 29. 4G and ITU
    • LTE, UBM and IEEE 802.16m are the principle 4G candidates.
    • They work with various antenna approaches including MIMO which uses multiple antennas at transmitter & receiver to improve performance.
    • ITU-R will select candidate technology in 2008 or 09 and develope detailed specifications in 2009-10.
    • Vendors begin implementation between 2010-12 with wide deployment occuring by 2015.
  • 30. Modulation Used in 4G.
      • QAM (Quadrature amplitude modulation)‏
        • QAM is a modulation scheme which conveys data by modulating the amplitude of two carrier waves.
        • These two waves are out of phase to each other.
        • Example of 4-QAM.
        • 64 QAM can send 6 bits at a time.
      • OFDM (Orthogonal frequency divison multiplexing)‏
        • OFDM is a is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers to carry data.
        • These sub-carriers typically overlap in frequency.
        • Each sub-carrier is modulated with a conventional modulation scheme as 64-QAM.
  • 31. OFDMA
      • Orthogonal Frequency Division Multiple Access (OFDMA).
      • In OFDMA frequency-division multiple access is achieved by assigning different OFDM sub-channels to different users.
      • OFDMA supports differentiated quality-of-service by assigning different number of sub-carriers to different users in a similar fashion as in CDMA.
  • 32. Long Term Evolution (LTE)‏
    • 3GPP is developing LTE.
    • LTE builds on GSM technology thereby easing migration for the many providers – but uses OFDM based air-interface.
    • Provides Spectrum flexibility i.e can be deployed in frequency band between 1.25 & 20 Mhz wide
    • Maximum data rate is expected to be 250 Mbps in a channel 20-Mhz wide.
  • 33. Ultra Mobile Broadband (UMB)‏
    • 3GPP2 is developing UMB
    • Could be deployed in frequency band between 1.25 & 20 Mhz wide.
    • UMB offers data rates for mobile users 288 Mbps downstream & 75 Mbps upstream using 20 Mhz channels.
    • The technology would provide a transition path for CDMA based carriers.
  • 34. IEEE 802.16m (WIMAX II)‏
    • Based of IEEE 802.16e (Mobile WIMAX)‏
    • Built on existing OFDMA technology.
    • Operates in frequencies between 10 and 66 Ghz.
    • Offer data rates upto 100 Mbps for mobile application and 1 Gbps for stationary users
  • 35. 4G 's Future
    • Barriers
      • Cost will hinder adoption
      • To achieve this higher speed the carriers would have to transmit over wide frequency slices which would be difficult because of limited spectrum availability.
      • Carriers are still recovering their cost they have invested in 3G.
    • Advantages
      • Transmission cost are lower for wireless technologies which are spectrally efficient as 4G promises to be.
  • 36. WiMax 802.16d
    • Worldwide interoperability for microwave access.
    • MAN technology based on standards in IEEE 802.16 specification.
    • Used for fixed wireless access with substantially higher bandwidth than most cellular networks.
    • Uses orthogonal frequency division multiplexing.
    • 802.16 will offer a mobile & quickly deployable alternative (Mobile Wimax) to cabled access networks.
    • 802.16 will provide mobilty upto 70/80 mi/hr.
  • 37. Physical Layer
    • Operates in the frequency band of 2-11 Ghz.
    • 256-carrier OFDM scheme is used
    • OFDM is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers to carry data
    • These sub-carriers typically overlap in frequency, but are designed not to interfere with each other
    • Each sub-carrier is modulated with a conventional modulation scheme (such as QAM).
    • Adaptive modulation and coding is used.
  • 38. Modulation Vs Bit Rate Source : References [1]
  • 39. Future Enhancements to 802.16
    • Spatial multiplexing
      • Also known as MIMO.
      • Increases the data rate in proportion to number of transmit antennas.
    • Hybrid ARQ
      • Uses an error control code in conjunction with the retransmission to ensure realiability.
      • Subsequent retransmissions are combined with the previous transmissions to improve reliability.
      • HARQ greatly increases the data rate.
  • 40. Conclusion
    • WiMax(802.16d/e) becomes a competitor against 3GPP 3.5G(HSDPA, High Speed Downlink Packet Access) for 4G wireless technology
      • WiMAXwill take over the 3G networks and become the 4G wireless technology –AT&T.
    • The high cost of adoption may cause hinderance initially but the 4G networks will capture the market by 2015.
    • To further increase the data rates above 4G we need to improve the modulation techniques as the spectrum is already congested and limited.
    • Backward compatability and Interoperability among different technologies & networks will be the important factor after the Introduction of 4G.
  • 41. References
      • A. Ghosh and D. R.Wolter SBC labs & J.G.Andrews and Runhua chen University of Texas, “ Broadband Wireless Access with WiMax/802.16,” IEEE Communication Magazine, Feb 2005.
      • Sixto Ortiz Jr , “4G Wireless Begins to Take Shape,” IEEE Computer Society Nov 2007.
      • S.Parkvall, E. Englund, Lundevall, and J. Torsner Ericsson Research, “Evolving 3G Mobile Systems WCDMA,” IEEE Communication Magazine Feb 2006.
      • TE Kolding, KI Pedersen, J. Wigard, F. Frederiksen & PE Mogensen Nokias Networks, “High Speed Downlink Packet Access: WCDMA Evolution, ” IEEE Vehicular Technology Society News FEB 2003.
      • GSM World : .
  • 42. References
      • UMTS World :
      • .