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Status of Next Generation Cellular and Wireless Local Area Networks and Current Research Activities. Mohsen Guizani Computer Science Department Western Michigan University mguizani@cs.wmich.edu. Western Michigan University. WMU is located in Kalamazoo, Michigan

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Status of next generation cellular and wireless local area networks and current research activities l.jpg

Status of Next Generation Cellular and Wireless Local Area Networks and Current Research Activities

Mohsen Guizani

Computer Science Department

Western Michigan University

mguizani@cs.wmich.edu


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Western Michigan University Networks and Current Research Activities

  • WMU is located in Kalamazoo, Michigan

  • WMU is one of 15 Michigan state schools

  • WMU has more than 28,000 students

  • The Computer Science is home to about 400 students

  • CS has 18 faculty members, 5 full professors, 7 associate professors, and 6 assistant professors.


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Outline Networks and Current Research Activities

  • Introduction

  • Cellular Coverage in the United States

  • Current Problems in the Telecommunications Industry

  • Review of Cellular Technologies

  • Wi-Fi: Competing or Complementary Technology?

  • The Future

  • Current Research Activities

  • Conclusions


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Current Research Activities Networks and Current Research Activities

  • Research Goal

  • 1x EV-DV Architecture

  • Resource Allocations Techniques

  • Cross Layer Design Overview

  • Intelligent Network QoS Protocols

  • Intelligent Network QoS Validation Protocol

  • Wireless QoS Based Routing Protocol


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Introduction Networks and Current Research Activities

  • A combination of factors has led to the current wireless situation in the US, which is rather poor in many respects

    • Rapid technological change

    • Rapid change in way people use technology

    • Poor business and investment decisions

    • Unrealistic expectations for new technologies

    • Competition on features and packages rather than underlying infrastructure

  • More thinking and intelligent decision making in future should enable vastly improved wireless service


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Cellular Coverage in the US: Networks and Current Research ActivitiesReason for Poor Coverage

  • Coverage is similar (often poor) because all providers use the same antenna towers

  • Much of the engineering behind tower placement is done in the old days of 3 watt cell phones at 800 MHz in cars with external antenna; in this day and age, the is much lower-powered units inside buildings or cars with no external antennas

  • NIMBY (“not in my backyard”) syndrome: Wealthy neighborhoods refuse to allow unsightly antenna towers


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Cellular Coverage in the US (Continued) Networks and Current Research Activities

  • Call by one of the authors from Baltimore, MD to Washington DC Dulles International Airport interrupted seven times due to coverage gaps—partly ascribed to the fact that there are five major cellular providers each of which has to build an entire network

  • The Yankee Group estimates that it would take $50B to $100B to bring cellular system up to snuff

    • Carriers do not have that kind of money

    • Would not solve political problems

      • Convenience trumps service quality

      • Relatively few people have abandoned landline phones


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Cellular Coverage in the US (Continued) Networks and Current Research Activities

Source: Wall Street Journal, 4/15/04


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Cost Constraints Networks and Current Research Activities

  • Minimal revenue per minute of air time

    • Brutal competition

    • Availability of free airtime and long distance packages

  • No “killer app” has ever materialized

    • Not cameras and ability to send photos

    • People want dependable voice communications

  • Cellular phones unsuitable as wireless modems

    • Promoters did not consider human factors

    • E-mail already well-served by dedicated devices such as the popular Blackberry by RIM


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Cost Constraints (cont.) Networks and Current Research Activities

  • Access to the Internet is done while at rest

    • Coverage problems would interrupt most operations if in motion

    • Cannot really do anything while driving or walking

    • Screen is too small

  • Competing technologies such as Wi-Fi are much better


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Problems Networks and Current Research Activities


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Problems (Continued) Networks and Current Research Activities


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Problems (continued) Networks and Current Research Activities


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Problems (continued) Networks and Current Research Activities


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1G Cellular Technology Networks and Current Research Activities

Advanced Mobile Phone Service (AMPS)

  • Analog

  • Widest coverage, much wider than digital systems

  • Phased out by 2008

    • Of concern to users of OnStar, which employs it—digital systems’ coverage poor by comparison

    • Being phased out because newer systems can support more customers per unit of bandwidth—bandwidth is most precious resource


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2G: GSM, CDMA, IS-95-a, iDEN Networks and Current Research Activities

Global System Mobile (GSM)

  • Initially Group Speciale Mobile; renamed Global System Mobile to give it an international flavor

  • Combined TDMA/FDMA system

  • Offered by AT&T, T-Mobile, and Cingular in the US

  • Advantage: With unlocked tri-band phone, users can have cellular service worldwide

  • Problem: Outside the US, reciprocal agreements with US providers expensive—$~4 per minute for airtime

  • Better solutions: Get subsidy unlock code for phone used in US—buy SIM card when abroad from kiosk; buy cheap tri-band phone in the US, then buy SIM card when abroad


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2G (Continued) Networks and Current Research Activities

Coded Division Multiple Access (CDMA)

  • Offered by Sprint and Verizon in the US

  • Verizon recently launched high-speed data service based on Phase 1 Evolution Data Only (1xEV-DO) in Washington, DC and San Diego, CA

  • Can handle the largest number of users per unit BW; most economically attractive


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2G (continued) Networks and Current Research Activities

Time Division Multiple Access (TDMA)

  • Use declining

  • Offered by AT&T and Cingular in the US

    Integrated Digital Enhanced Network (iDEN)

  • Developed by Motorola

  • Based on TDMA

  • Offered by Nextel in the US

  • Likely to be phased out in favor of CDMA-2000


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2.5G Networks and Current Research Activities

  • So-called 2.5 or 3rd generation wireless technologies unlikely to be profitable, especially given prices paid for spectrum

    • Main thrust is higher speed data

    • Cannot compete with Wi-Fi

    • Nextel is planning to bypass altogether

    • What is needed is data rate of >2 Mbps


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Beyond Networks and Current Research Activities

  • Various generations of cellular telephony more important to providers than users

    • Maximize revenue per unit bw

    • Users care more about features, cost, dependability

    • Many features being pushed are of dubious value

      • Multimedia Messaging Service (MMS)

      • Short Messaging Service (SMS)

      • Walkie-talkie feature

        • Reduces connect time to ~2 second versus 15 second dial time

      • Games

      • Downloadable ring tones

      • Replaceable covers


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Wi-Fi: Is It Really a Good Idea? Networks and Current Research Activities

  • IEEE 802.11b

  • Caught on very fast; manufacturers incorporate Wi-Fi chips in laptops; hopes are that this will be the new “killer app”

  • Wireless LAN equipment sales have been growing—Gartner Group says 2002 spending on all vendors is ~$2.3B; end-user spending increasing by about 50 percent for the last two years


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Wi-Fi: Security Issues Networks and Current Research Activities

  • Algorithm is used, Wired Equivalent Privacy (WEP) discredited

    • Encryption key length too short

    • Initialization vector implementation flawed

    • Scheme can be cracked quickly

    • Successor, WPA, is patch—not a fix

  • Vulnerable to broadband jamming, unless it uses frequency hopping as does Bluetooth


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Wi-Fi: Security Issues Networks and Current Research Activities(Continued)

Users do not seem to care

  • 70 percent of installations have not even implemented what little security measures there are

  • Incompatibilities among vendor equipment mean that Wi-Fi hot spots must implement lowest common denominator, i.e., no security

  • Wi-Fi user sitting next to “me” at Starbuck’s can intercept all transmissions to/from my computer

    • Doctor files in “my” computer

    • Impersonate “me” after “I” have logged off


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Wi-Fi: Security Issues Networks and Current Research Activities(Concluded)

Lack of scalability

  • PKI has not provided desired solution

  • Efficiently and rapidly propagating information about revoked encryption keys through large networks

  • Problem of where to store private or secret key safely in a manner that hacking cannot compromise

  • Smart cards may be the only viable solution, but most laptops have no smart card reader

    • Could be added through USB port


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Wi-Fi: Business Model Networks and Current Research Activities

  • No clear business model

  • Nobody making money off of Wi-Fi

    • Not a cost center, but a gimmick to attract customers

  • Issue of illegal use of Wi-Fi connectivity—who is liable?

    • Maryland homeowner recently held liable when someone used his hot spot for an illegal act

  • Airports and other such places look to Wi-Fi to recoup money no longer received from pay phones

    • Travelers unlikely to agree to open yet another account unless all places they frequent use same account


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Wi-Fi: Setup Difficulties and Network Incompatibilities Networks and Current Research Activities

  • Complex Windows’ network setup menus and options to set the SSID for each hotspot provider’s Access Point

  • Most non-technical laptop users are disinclined to do so

    • Technical help from kid behind counter at Starbuck’s, etc., is a losing proposition

  • Proliferation of different Wi-Fi hotspot providers means that users must open a separate account for each

    • T-Mobile account at 2,100 Starbuck’s or Kinko’s

    • Cometa account at MacDonald’s

    • FatPort account in Canada

    • Surf & Sip account at Foley’s Irish pubs

    • Toshiba account at Arizona’s Circle K stores

    • Waypoint account at a few select hotels


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Wi-Fi: User Fees and Speed Problems Networks and Current Research Activities

  • User fees

    • Disinclination of users to pay more access fees

    • Many feel they are already paying their Internet dues through home subscriptions

    • Lots of free Wi-Fi access points

      • From businesses that want to attract customers for their main product

  • Speed problems

    • Chips implementing 802.11b with WEP force all users to speed of slowest user at the hotspot


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Wi-Fi: Incompatibilities and Spectrum Shortage Networks and Current Research Activities

  • Incompatibilities between WEP and WPA

    • Problem has not received much press because commercial hotspots have not enabled either—due to vendor incompatibilities

  • Spectrum shortage

    • 802.11a has more spectrum allocated to it (which allows it to accommodate more concurrent users)—however has not yet caught on

    • Dual 802.11b/a access points and especially client user’s PCMCIA cards are very expensive; suffers from the same security vulnerabilities


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Wi-Fi: Standards and Scalability Networks and Current Research Activities

  • Standards

    • 802.11i, 802.11x, and 802.11e “standards” waiting in wings in various levels of agreement as to their final specs

    • Problem is that millions of deployed laptops and hotspots may make upgrade to better standards impossible

  • Scalability

    • Inherently not scalable

    • Operates in crowded unlicensed band with baby monitors, cordless phones, Bluetooth devices, microwave ovens

    • Limited number of channels—3 versus 8 for 802.11a


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Wi-Fi: Summary Networks and Current Research Activities

  • Wi-Fi has not really taken anything away from cellular

  • Cell phones are not as practical as wireless modems at 3 Kbps to 8 Kbps

  • Some CDMA systems (Sprint) encouraged use of cell phone itself for e-mail and messaging; however not practical due to the small size of the keyboard

  • Human factors: do people really want to make coffee shops another extension of their office?


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The Future Networks and Current Research Activities

  • Despite problems, wireless is here to stay

    • Convenience dictates that it users will demand it

    • Problems of “last mile” access

    • Need to set up and tear down networks quickly

      • Mobile ad hoc networks (MANETs) for military and for emergency responder use

  • Sets the stage for determining who will emerge victorious in future

    • Go beyond solving current problems and anticipate and solve future problems—foregoing; societal preferences, economics, scalability, and regulatory issues


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The Future (Continued) Networks and Current Research Activities

  • Realities of wireless solutions

    • Must be commercialized within months

    • Cannot hope for any regulatory protection given in the past to telecommunications monopolies

    • Will have to compete fiercely with other technologies for customer dollars—and hence for survival

  • Three issues of importance

    • Spectrum

    • Technology available to address problems

    • Socio-political issues


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The Future (Continued) Networks and Current Research Activities

  • Really is not a spectrum shortage

  • Even in areas such as Washington, DC, only about 20 percent of available cell phone spectrum used during peak hours

  • Real problem is more intelligent and efficient use of available spectrum


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Technology Available to address Problems Networks and Current Research Activities

  • Ultra-wideband

  • Wi-Max

  • Wireless mesh networks

  • Smart antennae

  • Software radios


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Technology Available to address Problems (cont.) Networks and Current Research Activities

Ultra-wideband

  • Uses short (~1 nsec) pulses which correspond to about 1 GHz bandwidth

    • Such pulses with 1 W peak power and repetition rate of 108 have average power of 100 mW spread over 1 GHz

      • Interference in a 1 kHz channel ~ 0.1 mW

  • FCC has allocated 3.1-10.6 GHz band

    • Currently in use by satellite uplinks and downlinks

  • Data rates up to 500 Mbits per second can be accommodated versus 700 kbps for Bluetooth


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    Technology Available to address Problems (cont.) Networks and Current Research Activities

    Ultra-wideband (Concluded)

    • UBW likely to become standard of choice for home networks

    • IEEE standard is 802.15.3a

      • Uses TDMA

      • Wireless Personal Area Network (WPAN)

      • 245 devices up to 90 m

      • Data rates 11 – 55 Mbps, declining with distance

      • AES encryption

      • Discussions now about dividing

    Expected shipments of UWB equipment


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    Technology Available to address Problems (cont.) Networks and Current Research Activities

    Wi-Max

    • Another emerging technology

      • Intended for distances up to 50 km at data rates up to 70 Mbps

      • Intended to provide broadband service to replace “last mile” where this is not cost-effective with conventional technology

      • May also take up some of the functions of Wi-Fi


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    Technology Available to address Problems (cont.) Networks and Current Research Activities

    Wireless mesh networks

    • Low-powered systems that pass messages from node to node on their way to their destination, not unlike what Internet nodes do with e-mail and other Transmission Control Protocol/Internet Protocol (TCP/IP) traffic

    • Any one node’s RF power output needs to be no more than what is required to close the link to the next nearest nodes

    • Redundant paths enhance the likelihood of end-to-end message integrity

    • Inherent is frequency reuse

    • Similar to old Ricochet network which went bankrupt because high costs of installation could not be recouped with small base of users


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    Technology Available to address Problems (cont.) Networks and Current Research Activities

    Smart antennae

    • Two stations communicating by wireless have absolutely no excuse for using omni-directional antennas

    • If each end could beam all of its RF energy towards the direction of the intended receiver, the RF spectrum would experience a massive increase in availability with no new frequency allocations

    • Beam forming can be computer-controlled for adaptive beam forming

      • In case of cellular base stations can be fast enough to accommodate vehicular users

      • In case of Wi-Fi can extend range; SF startup, Vivato, working on 128 beam implementation


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    Technology Available to address Problems (cont.) Networks and Current Research Activities

    Software radios

    • Software-configurable cell phones

    • To handle multiple systems, also Wi-Fi

    • Eliminate need to buy new cell phones every year or so


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    Socio-Political Issues Networks and Current Research Activities

    • Diverging international standards—China adopting its own wireless LAN standard, basically Wi-Fi with improved security

    • Ad hoc implementations—Some locations installing their own area-wide Wi-Fi to deal with problem of multiple accounts (Cerritos, CA)

    • Voice over IP

      • Currently a major trend, or at least major hyped trend

      • Promises many benefits

      • But many legal and regulatory issues unresolved, especially related to emergency response and USF


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    Conclusion Networks and Current Research Activities

    • Rate of change in telecommunications has been unprecedented

    • International cellular and wireless LAN industries have had two decades of gross miscalculations

      • Multibillion dollar bankruptcies

      • Endless miles of unused fiber optic cables

      • Digital cellular coverage in the US which is poor even by third world country standards

      • Wireless LAN standards whose lack of security has been an embarrassment

      • Hodge-podge of mutually incompatible cellular standards


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    Conclusion (continued) Networks and Current Research Activities

    • Industry now has the opportunity to plan wisely ahead

      • Forego the short-term gimmickry of downloadable ringing tones and designer-face-plates

      • Use US technological prowess in evolving technologies such as software radios, ultra-wideband, and smart antennas to forge standards that will with-stand the test of time and of consumer acceptance


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    Current Research Activities Networks and Current Research Activities

    • Research Goal

    • 1x EV-DV Architecture

    • Resource Allocations Techniques

    • Cross Layer Design Overview

    • Intelligent Network QoS Protocols

    • Intelligent Network QoS Validation Protocol

    • Wireless QoS Based Routing Protocol


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    Motivations Networks and Current Research Activities

    • High bit-rate applications (www, file transfer, full motion video) impose strong requirements/needs on the system capacity

    • Studies confirm a productive gain of between 7-8 hours a week when business users are equipped with mobile PCs and wireless access.

    • All-IP applications: end to end packet-switched network


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    Goals Networks and Current Research Activities

    • To develop a new dynamic and intelligent resource allocation technique for optimizing the average throughput of the wireless system.

    • Maximize the spectral efficiency and the number of users supported.

    • Develop QoS based protocol in the upper layer to assure the level of service required.


    Block diagram l.jpg

    Intelligent Network QoS Validation Protocol Engine Networks and Current Research Activities

    Network QoS

    MAC/Network QoS Mapping Layer

    MAC Layer

    Res. Alloc.

    Physical Layer

    Block Diagram


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    Competing technologies Networks and Current Research Activities


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    CDMA Family Networks and Current Research Activities

    • cdmaOne - IS-95A (2G)

      - IS-95B (2.5G)

    • CDMA 2000 1x (3G) 2000

    • CDMA 2000 3x MC (3G) 2001

    • 1xED-DO (3G) 2002

    • 1xEV-DV (3.5G) 2003


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    IS-95A Networks and Current Research Activities

    • 2G – 1995

    • Upto 14.4 kbps data rates

    • Used exclusively for circuit-switched voice

    • Used Convolutional channel coding

    • Used BPSK (fixed) modulation technique

      * BPSK: Binary Phase Shift Keying


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    IS-95B Networks and Current Research Activities

    • 2.5G – 1999

    • MAC layer enhanced over IS-95A

    • Up to 115 kbps data rates (64 kbps)

    • Up to 8 forward or reverse code channels can be simultaneously assigned to a MSU using Walsh codes and PN sequence masks

    • Code channels are transmitted at full data rates during a data burst.

    • Used Convolutional channel coding

    • Used BPSK modulation technique


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    CDMA 2000 1x Networks and Current Research Activities

    • 3G – 2000

    • Up to 307 kbps data rates (144 kbps)

    • Q-PCH enables to monitor F-CCCH and Paging Channel => improve battery life

    • Radio Configurations (RC) => additional data rates

    • Quality and Erasure indicator bit (QIB and EIB) on the reverse power control sub-channel.

    • Code channels are transmitted at full data rates during a data burst.

    • Used Convolutional and Turbo channel coding

    • Used QPSK modulation technique


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    CDMA 2000 3x MC Networks and Current Research Activities

    • 3G – 2001

    • Up to 2 Mbps data rates

    • Using 3 standard 1.25 MHz Chs within a 5 MHz band

    • Used Convolutional and Turbo channel coding

    • Used QPSK modulation technique


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    1xEV-DO Networks and Current Research Activities

    • 3G – 2002 1st Evolution phase of CDMA2000

    • Up to 2.4 Mbps data rates

    • No backward-compatibility with CDMA 2000

    • 2 inter-operable modes: 1x and 1xEV modes

    • Adaptive Rate Operation with respect to channel conditions

    • Adaptive Modulation and Coding (AMC)

    • Macro diversity via radio selection

    • Always-on operation of 1xEV-DO terminals in the active state

    • Multi-level modulation format (QPSK, 8-PSK, 16-QAM)


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    1xEV-DV Networks and Current Research Activities

    • 3.5G 2003

    • Forward peak data rate: 3.072 Mbps

    • Reverse peak data rate: 451.2 kbps

    • 3 new Chs to the forward link for the packet data operation (F-PDCH, F-PDCCH0, F-PDCCH1)

    • 3 new Chs to the reverse link to support operation of F-PDCH (R-RICH, R-CQICH, R-ACKCH)

    • Adaptive Modulation and Coding on the forward link in real time to adapt to the RF environment (QPSK, 8-PSK, 16-QAM)

    • Variable RF frame duration (1.25, 2.5 and 5 ms)

    • Fast selection of base station to serve forward link

    • No soft handoff on F-PDCH or F-PDCCH0 and F-PDCCH1


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    Tracing the DR Evolution Networks and Current Research Activities


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    CDMA Evolution Path Networks and Current Research Activities


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    1xEV-DV Architecture Networks and Current Research Activities


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    Logical and Physical Channels Networks and Current Research Activities

    • Physical Layer Interface

      • Control Information

    • MAC Layer

      • User’s control

      • Bearer Data

    • Other Layers

      • No new service interfaces


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    Forward Packet Data Channel Networks and Current Research Activities

    • Traffic channel combinations

      • operate in both mixed voice and data services and data-only services in the forward and reverse links.


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    New Physical Channels Networks and Current Research Activities

    • Reverse Link

      • Control Channel

        • R-ACKCH

        • RCQICH

    • Forward Link

      • Traffic Channel

        • F-PDCH

      • Control Channel

        • F-PDCCH


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    Adaptive Modulation and Coding Networks and Current Research Activities


    Adaptive modulation and coding63 l.jpg

    The base station assigns users the best modulation and coding rate for the instantaneous channel conditions (SINR).

    Reverse Link Feedback (R-CQICH)

    Base Station (Tx)

    Modulation and Coding Scheme

    Mobile Station (Rx)

    Channel Quality

    CHANNEL

    Adaptive Modulation and Coding


    Adaptive modulation and coding64 l.jpg
    Adaptive Modulation and Coding coding rate for the instantaneous channel conditions (SINR).

    • Provides higher data rate services by varying

      • The RF frame duration (1.25, 2.5 or 5 milliseconds)

      • The number of bits per RF frame (between 408 and 3864 bits)

      • The coding algorithm

        • QPSK (Quadrature Phase Shift Keying)

        • 8-PSK (8-states Phase Shift Keying)

        • 16-QAM (16-state Quadrature Amplitude Modulation) .


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    F-PDCH Data Rates coding rate for the instantaneous channel conditions (SINR).

    • Data rates depending on F-PDCH packet size and RF frame duration.

    • The RF frame duration

      • “Number of Slots per Sub-packet” (1 slot = 1.25 ms)


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    Hybrid ARQ coding rate for the instantaneous channel conditions (SINR).

    • Automatic Repeat reQuest (ARQ)

      • Immigrates from MAC layer to Physical layer for improving performance

      • A mechanism supporting retransmission of frames received in error

    • Hybrid ARQ

      • Chase combining, each retransmission repeats the first transmission or part of it.

      • Incremental redundancy (IR), each retransmission provides new code bits from the mother code to build a lower rate code


    Amc and hybrid arq l.jpg
    AMC and hybrid ARQ coding rate for the instantaneous channel conditions (SINR).

    • On a single carrier, 1xEV-DV can efficiently serve both data and legacy services (e.g., voice) by combining of Fast AMC and Hybrid ARQ

      • Fast AMC is a link adaptation scheme where the base station assigns users the best modulation and coding rate for the instantaneous channel conditions.

      • Hybrid ARQ improves throughput and enables fast AMC by making the initial modulation and code rate selection process tolerant to selection error.


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    F-CPCCH coding rate for the instantaneous channel conditions (SINR).

    F-CPCCH

    R-PICH

    F-PICH

    F-PICH

    R-PICH

    (F-DCCH/FCH/SCH)

    R-CQICH

    (R-DCCH/FCH/SCH)

    F-PDCCH

    MOBILE

    F-PDCH

    BTS 1

    BTS 2

    R-ACKCH

    (F-DCCH/FCH/SCH)

    (R-DCCH/FCH/SCH)

    Cell Selection

    • The mobile station selects one base station from its active set

    • The selection based on the RF quality measured (SINR) by the mobile station


    Flexible tdm cdm multiplexing l.jpg
    Flexible TDM/CDM Multiplexing coding rate for the instantaneous channel conditions (SINR).

    • 1xEV-DV was designed to support all services

      • Services that use large packets

      • Services that use small packets

    • To reach the goal, TDM and CDM are included into the 1xEV-DV specifications

    • TDM/CDM multiplexing allows the selection of both the number of timeslots and the number of Walsh codes allocated to a user.


    Tdm cdm l.jpg

    TDM coding rate for the instantaneous channel conditions (SINR).

    TDM/CDM

    Code Space

    Waste

    Used by other

    traffic

    Required

    Required

    Frame Duration

    TDM/CDM

    • The TDM/CDM in 1xEV-DV system maximizes system throughput by providing optimal modulation and coding rate assignments to all services while maintaining frame fill efficiency.

    • A small packet may receive a few of the Walsh codes, and the remaining Walsh codes can be used by another user, improving overall system capacity


    Modulation and coding schemes mcs l.jpg
    Modulation and Coding Schemes (MCS) coding rate for the instantaneous channel conditions (SINR).


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    AMC Fixed Threshold Method coding rate for the instantaneous channel conditions (SINR).

    • AMC has a set of n MCS levels

    • MCS set has a corresponding throughput vs. av. Channel SINR denoted by

    • These throughput values can be graphically represented, where the curves intersect with each other.

      SINR at intersection points are threshold values, denoted by


    Amc fixed threshold method73 l.jpg
    AMC Fixed Threshold Method coding rate for the instantaneous channel conditions (SINR).

    • These threshold points partition the range of SINR into n regions, denoted by

    • The kth MCS, namely Mk is assigned to the region

      if the following condition is satisfied


    Amc fixed threshold method74 l.jpg

    SINR coding rate for the instantaneous channel conditions (SINR).

    MCSi

    Threshold values, fixed

    Channel Estimate

    γi

    }

    AMC Fixed Threshold Method

    • With this corresponding between the MCS’s and the average SINR, Mk is selected for the next frame if the average channel SINR in the current frame lies in the region


    Disadvantages of tm l.jpg
    Disadvantages of TM coding rate for the instantaneous channel conditions (SINR).

    • Error in the estimation of average channel SINR can cause inappropriate selection of MCS resulting in a degradation of the performance

    • The threshold values associated with the MCSs are not jointly optimized based on the overall stochastic behavior of the users’ SINR  degrade the efficiency of the overall system resources.


    Optimized method l.jpg

    SINR coding rate for the instantaneous channel conditions (SINR).

    MCSi

    Threshold values, optimized

    Channel Estimate

    γi

    }

    Optimized Method

    The threshold values associated with the MCSs are jointly optimized based on the overall stochastic behavior of the users’ SINRs  The goal is:

    Higher overall throughput


    Percentage of users served by a mcsi l.jpg
    Percentage of users served by a MCSi coding rate for the instantaneous channel conditions (SINR).

    P1 + P2 +  + PN = 1

    • The SINR is a random variable (r.v.) achieved by an arbitrary user at a given instant

    • We prove ordinarily that Pi is a discrete random function that is dependent on the users’ joint SINRcumulative distribution function (CDF) and data rate granularity (N).


    Throughput optimization l.jpg
    Throughput Optimization coding rate for the instantaneous channel conditions (SINR).

    • Consider the event {SINRx} where x is a real number in the interval [0,). We write the probability of this event as

    • The function F(x) is the CDF of the r.v. SINR. In our case, F(0) ≡ F() = 0 and F(SINRN+1) ≡ F() = 1. Thus, we can rewrite Pi as


    Throughput optimization79 l.jpg
    Throughput Optimization coding rate for the instantaneous channel conditions (SINR).

    • In terms of discrete CDF functions, Piis expressed as


    Sinr i thresholds l.jpg
    SINR coding rate for the instantaneous channel conditions (SINR).i thresholds:

    • SINRi thresholds for variable bit rates: The SINRi threshold associated with a MCSiis determined by

    Bit rate can be calculated

    GP can be calculated

    RCi is given by


    Throughput calculations l.jpg
    Throughput calculations: coding rate for the instantaneous channel conditions (SINR).

    i represents the throughput that can be transmitted by a base station

    Let also eff_irepresents the effective throughput that can be received by the users who can achieve an SINR in the range [SINRi, SINRi+1)


    Simulation model l.jpg

    12 coding rate for the instantaneous channel conditions (SINR).

    11

    10

    13

    4

    3

    9

    14

    5

    1

    2

    8

    15

    6

    7

    19

    16

    17

    18

    Simulation Model

    • Assume there are M possible users’ realizations over a certain period of time, then P is a member in an M-size set {Pj: j = 1, 2, … , M}.

    • We consider 19 3-sector cells located on a hexagonal grid and used the SINR calculations as shown


    Effective throughput l.jpg
    Effective throughput coding rate for the instantaneous channel conditions (SINR).

    Effective aggregate throughput for 100 different realizations for users’ locations selected at random within the cell range


    User data rate vs users density l.jpg
    User Data Rate vs. Users Density coding rate for the instantaneous channel conditions (SINR).

    Effective aggregate throughput as a function of the users density. Here the radius was changing inversely proportional to the users density.


    Intelligent network qos validation protocol l.jpg

    Intelligent Network QoS Validation Protocol Engine coding rate for the instantaneous channel conditions (SINR).

    Network QoS

    MAC/Network QoS Mapping Layer

    MAC Layer

    Res. Alloc.

    Physical Layer

    Intelligent Network QoS Validation Protocol

    Interaction between the Physical/MAC layers and the

    Network QoS validation protocol


    Intelligent network qos validation protocol contd l.jpg

    Application coding rate for the instantaneous channel conditions (SINR).

    Bandwidth

    Delay

    Jitter

    Loss

    other

    MAC/Network QoS mapping

    MCS1

    MCSi

    candidates

    MCS2

    MCSi

    Intelligent Network QoS Validation Protocol (contd.)


    Qos classes l.jpg
    QoS classes coding rate for the instantaneous channel conditions (SINR).


    Intelligent network qos validation protocol contd88 l.jpg
    Intelligent Network QoS Validation Protocol (contd.) coding rate for the instantaneous channel conditions (SINR).

    • At the MAC layer

      • Network resources are allocated based on the MAC QoS

    • At the network layer

      • Network resources are validated based on the network QoS requirements, which are traffic type dependent


    Cross layer design l.jpg
    Cross Layer Design coding rate for the instantaneous channel conditions (SINR).

    • Goal

      • Provide efficient methods of allocating network resources and applications

      • QoS support in all layers

      • Dynamic protocol design

      • Jointly optimize the network performance

    • Tradeoff

      • Performance versus complexity and scalability


    Cross layer design contd l.jpg
    Cross Layer Design (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Why?

      • There exists direct coupling between physical layer and upper protocol layers

      • Several upper layer protocols do not get advantage of the wireless medium information available within the physical and MAC layer.


    Intelligent network qos protocols l.jpg
    Intelligent Network QoS Protocols coding rate for the instantaneous channel conditions (SINR).

    • At the network layer

      • Intelligent network QoS validation protocol

      • Wireless QoS based routing protocol


    Intelligent network qos validation protocol contd92 l.jpg
    Intelligent Network QoS Validation Protocol (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Approach

      • Model the system as an objective function to be maximized based on network QoS parameters

      • Not to violate the MAC QoS constraints.

      • Optimizing the objective function is an NP-Complete problem

      • Use heuristic techniques

        • Genetic algorithms

        • Fuzzy logic

        • Simulated annealing

        • Etc.


    Wireless qos based routing protocol l.jpg
    Wireless QoS Based Routing Protocol coding rate for the instantaneous channel conditions (SINR).

    • Features

      • Low overhead control traffic

      • On demand operation

      • Optimal route computation

      • Network configuration change

      • Distributed operation


    Wireless qos based routing protocol contd l.jpg
    Wireless QoS Based Routing Protocol (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Communication

      • An optimum size of the protocol update control messages

      • The frequency of neighbor update messages

      • Modified version of the route discovery protocol implemented by most of the distance vector routing protocol


    High level protocol design l.jpg
    High Level Protocol Design coding rate for the instantaneous channel conditions (SINR).

    • QoS based routing protocol suite high level design

      • Optimization of resource usage

        • Advertise resource information to all neighboring nodes

      • Graceful network performance degradation

        • Restrict the update message flooding to the neighboring nodes only

        • New neighboring information exchange policy techniques using some heuristic algorithms


    High level protocol design contd l.jpg
    High Level Protocol Design (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Adaptive routing protocol

      • In case of a change in the network or node resources, update messages will be triggered based on our neighboring information exchange policy

    • Granularity of the routing decision

      • Source and destination-based routing approach: the traffic between a given source and destination will be routed over the same route.

    • On the fly determination of feasible paths


    High level protocol design contd97 l.jpg
    High Level Protocol Design (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Performance objectives while computing QoS-based paths

      • Achieve better network throughput by achieving low route-request blocking probability while providing QoS based paths

    • Optimum routing overhead during the computation, communication, and routing information storage

      • Minimize the routing overhead caused by the rapid change of some of the network resources as well as the call setup frequency


    High level protocol design contd98 l.jpg
    High Level Protocol Design (contd.) coding rate for the instantaneous channel conditions (SINR).

    • Route computation

      • Use Kalman-filter or equivalent heuristic techniques in order to determine the best path

    • Routing information storage

      • Maintain a partial routing table


    Conclusion99 l.jpg
    Conclusion coding rate for the instantaneous channel conditions (SINR).

    • Improve the overall throughput of the wireless network

      • SINR AMC MCS Compute the best threshold

    • Use cross layer design technique

    • Design a new protocol at the network layer to assure better QoS based on the traffic type

    • Design a new QoS based routing protocol

      • Less control message overhead

      • Improve call blocking probability


    Future work l.jpg
    Future Work coding rate for the instantaneous channel conditions (SINR).

    • Simulation study using OPNET

    • Performance evaluation of the developed protocols (control message overhead, CBP, etc.)

    • Comparison study of the proposed QoS routing protocol with the existing protocols


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