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

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Presentation on theme: "Next Generation (NextG) Wireless Networks 7/2/2004 Farid Farahmand."— Presentation transcript:

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, , 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 dont 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 BlocksBins Pack IP PktsTime 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 Wireless Internet Bkbone QoS Over Air


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