Issues and Challenges of Next Generation Mobile Communications

1. Issues and Challenges of Next Generation Mobile Communications Presentation slides for the course CSE 6065 – Advanced Mobile Communications Mohammad MamunElahi Assistant Professor Department of Computer Science and Engineering United International University mmelahi@cse.uiu.ac.bd Slides are adapted from book slides of J. Schiller and talk slides of Dr. Dharma P. Agrawal

2. Computers for the next decades ? • Computers are integrated • small, cheap, portable, replaceable - no more separate devices • Technology is in the background • computers are aware of their environment and adapt (“location awareness”) • computer recognize the location of the user and react appropriately (e.g., call forwarding, fax forwarding, “context awareness”)) • Advances in technology • more computing power in smaller devices • flat, lightweight displays with low power consumption • new user interfaces due to small dimensions • multiple wireless interfaces: wireless LANs, wireless WANs, regional wireless telecommunication networks etc. (“overlay networks”) Issues and Challenges of Mobile Communications

3. Mobile communication • Two aspects of mobility: • user mobility: users communicate (wireless) “anytime, anywhere, with anyone” • device portability: devices can be connected anytime, anywhere to the network • Wireless vs. mobile Examples stationary computer  notebook in a hotel wireless LANs in historic buildings  Personal Digital Assistant (PDA) • The demand for mobile communication creates the need for integration of wireless networks into existing fixed networks: • local area networks:standardization of IEEE 802.11 • Internet: Mobile IP extension of the internet protocol IP • wide area networks: e.g., internetworking of GSM and ISDN Issues and Challenges of Mobile Communications

4. Some Applications • Vehicles • transmission of news, road condition, weather, music • personal communication using GSM • position via GPS • local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy • Emergencies • early transmission of patient data to the hospital, current status, first diagnosis • replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc. • crisis, war, ... Issues and Challenges of Mobile Communications

5. Typical application: road traffic UMTS, WLAN, DAB, GSM, cdma2000, TETRA, ... ad hoc Personal Travel Assistant, DAB, PDA, laptop, GSM, UMTS, WLAN, Bluetooth, ... Issues and Challenges of Mobile Communications

6. Effects of device portability • Power consumption • limited computing power, low quality displays, small disks due to limited battery capacity • Loss of data • higher probability, has to be included in advance into the design (e.g., defects, theft) • Limited user interfaces • compromise between size of fingers and portability • integration of character/voice recognition, abstract symbols • Limited memory • limited value of mass memories with moving parts • flash-memory or ? as alternative Issues and Challenges of Mobile Communications

7. Wireless networks in comparison to fixed networks • Higher loss-rates due to interference • emissions of, e.g., engines, lightning • Restrictive regulations of frequencies • frequencies have to be coordinated, useful frequencies are almost all occupied • Low transmission rates • local some Mbit/s, regional currently, e.g., 9.6kbit/s with GSM • Higher delays, higher jitter • connection setup time with GSM in the second range, several hundred milliseconds for other wireless systems • Lower security, simpler active attacking • radio interface accessible for everyone, base station can be simulated, thus attracting calls from mobile phones • Always shared medium • secure access mechanisms important Issues and Challenges of Mobile Communications

8. Wireless systems: overview of the development cordlessphones satellites cellular phones wireless LAN 1980:CT0 1981: NMT 450 1982: Inmarsat-A 1983: AMPS 1984:CT1 1986: NMT 900 1987:CT1+ 1988: Inmarsat-C 1989: CT 2 1991: CDMA 1991: D-AMPS 1991: DECT 199x: proprietary 1992: GSM 1992: Inmarsat-B Inmarsat-M 1993: PDC 1997: IEEE 802.11 1994:DCS 1800 1998: Iridium 1999: 802.11b, Bluetooth 2000: IEEE 802.11a 2000:GPRS analogue 2001: IMT-2000 digital 200?: Fourth Generation (Internet based) 4G – fourth generation: when and how? Issues and Challenges of Mobile Communications

9. Network Network Simple reference model used here Application Application Transport Transport Network Network Data Link Data Link Data Link Data Link Physical Physical Physical Physical Medium Radio Issues and Challenges of Mobile Communications

10. service location new applications, multimedia adaptive applications congestion and flow control quality of service addressing, routing, device location hand-over authentication media access multiplexing media access control encryption modulation interference attenuation frequency Influence of mobile communication to the layer model Application layer Transport layer Network layer Data link layer Physical layer Issues and Challenges of Mobile Communications

11. Overlay Networks - the global goal integration of heterogeneous fixed andmobile networks with varyingtransmission characteristics regional vertical handover metropolitan area campus-based horizontal handover in-house Issues and Challenges of Mobile Communications

12. Problems and issues of mobile computing • Constraints of mobile computing and their impact on distributed systems • All constraints are intrinsic to mobility • Mobile elements are resource poor • Mobility is inherently hazardous • Mobile connectivity is highly variable • Mobile elements rely on a finite energy source • Solution lies in the mobile client being ADAPTIVE Issues and Challenges of Mobile Communications

13. Mobile Computing Properties • Wireless Communication • Network connectivity is essential for mobile computing platforms • Mobility • Issues relating to dynamic information change • Portability • What good is a device that only lasts 5 minutes on battery power? • Wireless Communication Issues • Lower bandwidth, higher error rates, signal path problems • Increased communication latency, retransmissions, and timeout delays • Mobility affords greater range of problems, e.g. moving from one coverage area to another Issues and Challenges of Mobile Communications

14. Low Bandwidth • There is a discernible difference in bandwidth between wireless and wired connections • Two techniques to improve bandwidth • (1) Install more wireless cells by overlapping cells on different wavelengths, or • (2) reduce transmission ranges • Other techniques: compression and logging • Available bandwidth is largely user-perceived, so tricks such as scheduling communication to ``improve” bandwidth utilization Issues and Challenges of Mobile Communications

15. Other Issues • High bandwidth variability • Applications should adapt to mobile devices changing from wired to wireless modes (and vice versa) • Heterogeneous networks • Moving from one service area to another Issues and Challenges of Mobile Communications

16. 3G / WLAN Integration Issues and Challenges of Mobile Communications

17. Heterogeneous Wireless Network Issues and Challenges of Mobile Communications

18. Why do you need Multi-Service ? Mobile Users are always best connected (ABC) to the IP-based core network through a heterogeneous wireless system for a variety of services with quality of service (QoS) guarantee and self-managing roaming capability Issues and Challenges of Mobile Communications

19. What is Multi-Service ? • Mobile Users must be able to access a large variety of services with seamless mobility and Quality of Service (QoS) guarantee. • Multi-service means a great variety of services: voice, multimedia, messaging, e-mail, information services (e.g., news, stocks, weather, travel, etc.), • Internet fax, m-commerce, entertainment, location-based services, health-care services, and so on. • Multi-service means that a user has the capability to simultaneously receive manifold services from the Internet. Issues and Challenges of Mobile Communications

20. What is Multi-Network ? • Legacy (e.g., cellular or WLAN single-hop networks) and new network paradigms, such as the Wireless Regional Area Network (WRAN), Wireless Personal Area Network (WPAN), Mobile Ad hoc Networks (MANETs), and Wireless Wide Area Network (WWAN) are also expected to coexist, interact, and interoperate. • Networks operated in different radios are distinguished by characteristics such as data transmission rate, delay, radio coverage, price etc. • Heterogeneous wireless networks must cooperate to provide an underlying “data transport service” that is transparent to applications and hence users. Issues and Challenges of Mobile Communications

21. What is in a Multi-mode Terminal ? • Multi-mode mobile stations (MSs) are expected to play a critical role in heterogeneous wireless network (HWNs). • Multi-mode terminals may include interfaces for WWAN, WLAN, WMAN, WPAN, and so on. • Multiple communication capabilities (e.g., connecting to two or more different wireless access networks simultaneously) must be opportunistically exploited to ensure the user always has “the best connectivity” at any given time and location for each type of service. • Multi-mode terminals has the capability to • migrate among multi-network. Issues and Challenges of Mobile Communications

22. Mobility Management Issues and Challenges of Mobile Communications

23. Mobility and Service Continuity A multi-mode terminal (cellular, IEEE 802.11a, and IEEE 802.11 b/g) executes two applications (voice and ftp) while it moves from position 1 to 5, and experiences cellular, IEEE 802.11 b/g, and IEEE 802.11a. Issues and Challenges of Mobile Communications

24. Seamless Handoff ( Horizontal & Vertical Handoff ) • Automatic network detect and seamless handoff management in a multi-network context. • A horizontal handoff migrates a connection between two homogeneous networks. • A vertical handoff deals with the migration between heterogeneous networks (e.g., from cellular to WLAN). • In a multi-network context, a handoff procedure is a complicated problem that involves multiple interfaces with multiple connections. Issues and Challenges of Mobile Communications

25. Cross-Layer Solutions • Mainly for handoff management • Provide network layer handoff with help of link layer • Obtains link layer information like signal strength, movement detection, etc in advance • Reduces packet loss and handoff latency Issues and Challenges of Mobile Communications

26. OSI Layers and Mobility Management Cross Layer (L3 + L2) Issues and Challenges of Mobile Communications

27. Adaptive QoS-based Network Selection A QoS-based network selection algorithm is implemented in the horizontal and vertical layer. Issues and Challenges of Mobile Communications

28. Open Issues in Network Selection • How to define the best connectivity opportunity? • How to quantify “Always Best Connectivity”? • Best QoS available (network condition) • Service requirements • Cost • User preferences • How to find a good trade-off among all the above factors? Issues and Challenges of Mobile Communications

29. Questions???? Issues and Challenges of Mobile Communications