Next Generation (NextG) Wireless Networks

1. Next Generation (NextG)Wireless Networks 7/2/2004 Farid Farahmand

2. Outline • Description of wireless networks • Wireless network evolution • Wireless key technologies • Current researches

3. Wireless Networks • Motivated by people-on-the-go • PCs availability, Internet usage, Mobile life • Aimed is to establish wide-area voice data communications • Includes mobile systems (cellular telecommunication systems)

4. Wireless Network Evolution • First generation (1G): Analog voice systems • No standardization • Second Generation (2G): Digital voice systems • Currently deployed systems • CDMA, GSM (Global System for Mobile communication), PDC (Japan) D-AMPS (Digital Advanced Mobile Phone System) • PCS Systems • Second Generation – advanced (2.5G): Combining voice and data communications • Providing enhanced data rate • Two basic technologies: • GSM-based (high baud rate) • GPRS (General Packet Radio Service) • Utilizes voice time slots to send packet traffic • An overlay over the existing voice system • Should really be called 2.1G!! • Any standards?

5. Wireless Network Evolution • Third Generation (3G): Digital voice and data communications • Developing a more general mobile network • Handling Internet access, email, messaging, multimedia • Access to any services (voice, video, data, etc.) • Requires high quality transmission • Forth Generation (4G): All-IP mobile networks • Ubiquitous wireless communications • Transparent to any services • Integrating multinetworks

6. Third Generation (3G) • Two basic proposals to handle voice and data • Ericsson: Universal Mobile Telecommunications systems (UMTS) • Compatible with European GSM • Backed by ETSI and Japan • Qualcom: CDM2000 • Not compatible with GSM (cannot hand off called to GSM-based cells) • Compatible for IS-95 (supported by U.S) • 3G Standards • 1999 UMTS took over and an agreement was made over setting some standards • A revolutionary technology with unlimited potential or not so great? • Major competing technologies • Bluethood • Wireless LAN (IEEE 802.x standards) – also known as WiFi • Short range wireless communications • Highly utilized and very popular: offices, airports, coffee shops, universities and schools • Two basic modes of operations: • Ad-hoc networking: computers send data to one another • Access point:: sending data to the base station

7. Forth Generation Wireless Networks • Otherwise known as NextG, Beyond 3G, 4G, and more! • Motivation • Providing all available services to highly mobile people (anytime anywhere) • Use your wireless device anywhere for listening to music, shopping (m-commerce) , downloading (file transfer), watching video (live streaming) • Multiple applications (talk and use Internet services at the same time) • Objectives • Total convergence of the wireless mobile and wireless access communications (developing a broadband wireless network) • Ubiquitous wireless communications and services • Integration of multi-networks using IP technology • Similar technology to the wired Internet where users are freed from their local networks • All-IP based wireless networks • Not just IP end-to-end but over-the-air packet switching • Supporting native wireless IP mode • Highly integrated • High bandwidth / high-speed wireless • Highly compatible with wired network infrastructures • ATM, IP, ATM

8. 4G Technology Challenges • Supporting heterogeneous multitude of systems • Includes multiple networks: • Cellular telecommunication systems • Digital video broadband • Digital audio broadband • Wireless LAB, Bluethood-based networks • Open communication network: infrastructure independent which can access to any services and applications (now and in the future!) • Complete compatibility between wireless and wired networks through gateways • Supporting statistical multiplexing of heterogeneous data over-the-air • Latency, noisy environment, unpredictable discontinuities and loss, etc. • High-speed wireless transmission over the air • High performance physical layer • 20Mbps (2G: 28Kbps, 3G: 2Mbps) • Scarce bandwidth availability • Efficient frequency spectrum utilization • Efficient hand off • Dynamic bandwidth allocation • Advanced digital transmission technology (modulation, low power devices, etc.)

9. 4G Key Issues - Research Areas • IP Addressing • Mobile IPv6 protocol provides unbroken connectivity between mobile nodes • Architecture • Horizontal communications between different access technologies using gateways • Including local-area access technology (3G only covers wide-area packet switched cellular technology) • Hand off • Fast hand off due to high-speed transmission • High reliability • QoS framework • Interoperability between wireless and wired networks • QoS classes: Conversational (most delay sensitive), streaming, interactive, background (least delay sensitive) • Fair bandwidth allocation • Class-based QoS over the air

10. 4G Key Issues - Research Areas • Security and billing • Essential in e-commerce • More than just authentication and encryption (as in 3G) • End-to-end security mechanisms between the Internet server (wired) and the mobile terminal • No translation and decomposition of the data at the gateways • Usage fee • Volume based or time-based? • TCP performance in wireless / mobile communications • Research shows unmodified standard TCP is not well aligned with cellular boundaries • New protocols have been developed: Snoop, Split connections, other end-to-end protocol families • Using Snoop agent the exchange of TCP packets and ACKs are monitored and performs local retransmissions as needed (OBS-like!) • Split-connections deals with wireless and wired network inconsistencies (gateways, translations, etc.) • Two separate connections between fixed and mobile hosts • End-to-end protocols deal with retransmission timeout causing the TCP window to shrink too often

11. QoS-enabled MAC Protocol- Scheduling Problem • Mac protocols: • Wirelines: FIFO, Generalized Processor Sharing (GPS) • Wireless: Random Access Protocols • Voice-based MAC protocols don’t work well for multimedia applications • No packet ordering is supported, no fair packet loss sharing • Multimedia traffic exhibit highly bursty traffic rates • Each class of traffic has a QoS requirement and traffic rate characteristics • A new MAC protocol with fair packet loss sharing scheduling for 4G is proposed • Assumes time-division/code-division multiple access wireless system with IP transmission • Objective (conflicting): • support as many users as possible (high channel utilization), • dropped packets between all users are shared fairly • Basic Idea: • Allocate minimum amount of resources to satisfy the QoS requirements • Maximize the total number of scheduled packets • How to calculate the number of packets dropped: • Give enough BW to meet the QoS guaranteed level, drop the rest • Maximize the number of packets sent: bin-packing problem Pack Blocks Bins IP Pkts Time Slots

12. Class-based QoS over Air Interface in 4G • Basic characteristics: • Flexible (support various services) • Effective (easy negotiation mechanism to handle QoS over air) • Basic Idea: • Check congestion over the air • When congestion occurs, users with lower QoS have to back off their transmission rate • The extent of the back off depends on the class it belongs to • Basic problem is possible under-utilization • Supports any number of QoS classes based on the specified resource assignment for each class QoS Over Air Wireless Internet Bkbone