PRIN2005 – Women Overall research

1. PRIN2005 – WomenOverall research University of Florence Research Unit PRIN Women

2. Research Activity • WP3 Space division multiple access for QoS guaranteed wide-band connection • WP4 Mesh Networking Protocol • WP5 Secure applications, development and trials PRIN Women

3. WP3 - Space division multiple access for QoS guaranteed wide-band connection • Link Adaptation strategy in a wireless multipath-fading affected environment • OFDMA TDD Scenario • Adaptive modulation and coding based on: • Received power • Error rate • Adaptive subcarrier allocation • IEEE 802.16 Scheduling in OFDM mode • Data & VoIP traffic • Heterogeneous Scenario with IEEE 802.11 hot-spots • IEEE 802.16d Centralized Scheduling in for mesh networks • Data & VoIP traffic • Heterogeneous Scenario with IEEE 802.11 hot-spots • Scheduling procedures in OFDMA mobile environment • Adaptive modulation & queue monitoring PRIN Women

4. Adaptive Modulation • It selects automatically the modulation order for: • minimize the error probability; • maximize the transmitting rate; Channel state adaptativity • The AM (Adaptive Modulation) techniques manage the adaptivity basing on: • channel state information and received power • receiver quality in terms of error rate PRIN Women

5. Adaptvity management Error rate adaptivity CSI Adaptivity PRIN Women

6. Following the hypotheses of the IEEE 802.16e standard we have considered to use QPSK, 16 QAM and 64 QAM. For what concerns the coding operation we have introduced a block coder with rate ½ e ¾, with the last one obtained by puncturing the ½ coded word. Proposed system The modulation and coding order is selectted by comparing the CSI for each subchannel with a threshold already calculated in a theoretical way. • Two different adaptation techniques have been studied, reflecting two differet approaches. They differs on the threshold values: • “Target Block Error Rate” • Maximum throughput PRIN Women - 5th Meeting

7. User 1 User 2 User 3 Slot adaptive allocation User 1 • In the oldsystems the allocationwasfixed Channel response • The slot allocationtoeachuser can bedoneadaptively subcarriers User 2 Channel response • Eachuser can haveitsownchannelcharacteristics subcarriers User 3 • The aimisto allocate the slotsto the usersbyfollowing the channelconditions Channel response subcarriers PRIN Women - 5th Meeting

8. Quality of Service – Application to WiMAX Managed traffic types: UGS, rtPS, nrtPS, BES BS Scheduler Priority: 1 = Max 4 = Min Strict semi-preemptive priority UGS rtPS nrtPS BES 1 2 3 4 PFQ Type Connection IDentifier PBRR EDF Priority Enhanced WFQ CID CID CID CID CID CID PRIN Women

9. Application environment Joint management of Best-Effort and VoIP traffic in a PMP uplink scenario with a central Base Station and a variable number of user terminals Voice over Internet Protocol (VoIP): very sensible to transmission delays and queue waiting time no request UGS Class  guaranteed bandwidth PBRR scheduling Best-Effort: low sensibility to delays and with low constraints contention requests BES Class  not guaranteed bandwidth WFQ scheduling PRIN Women

10. Proposed system VoIP traffic Data traffic UGS class BES class A guaranteed bit rate is reserved on each frame in order to preserve a target QoS. A contention procedure is done for requesting the bandwidth that is divided among the different MSs; the assigned resources depends on the scheduling policy. The MS can use different modulation levels according to the received power (inverse proportion to the distance) Accordingly with the IEEE 802.16e standard, the nodes are mobile. PRIN Women

11. Scheduling policies EDF (Earliest Deadline First): the deadline is referred to the maximum delay threshold VoIP traffic WFQ (Weighted Fair Queueing): the weight is referred to the amount of traffic in the queue. PQ (Priority Queueing): the k-th class MS cannot be served until all the k-1class MS queue are empty Data traffic RR (Round Robin): the bandwidth is devided in equal parts between the classes. WPQ (Weighted Priority Queueing): the bandwidth is divided between the three classes with a certain weight PRIN Women

12. BS: Base Station SS: Subscriber Station IEEE 802.16-2004 • Last mile coverage in metropolitan are network with broadband wireless access • Elevated coverage range (up to about 50 Km) • Two working freqency intervals: • 10 – 66 GHz • 2 – 11 GHz • PMP and Mesh architectures PMP 2-11 GHz 10-66 GHz MESH 2-11 GHz PRIN Women

13. Mechanism for entrance/exit from the network Bandwidth requests propagation Resource allocation mechanism Analyzed centralized scheduling policy PRIN Women

14. WP4- Mesh Networking Protocol • Interoperability Issues with 802.11 • Two bridging solutions • MAC direct interconnection • Ethernet Bridge interconnection PRIN Women

15. Bridging solutions MAC direct interconnection Ethernet Bridge interconnection PRIN Women

16. WP5 - Secure Applications, Deployment and Trials • Firewalling in mesh networks • Bloom filters • Bloom filtering applied in mesh environments • Analysis of WiMAX security • IEEE 802.16d-2004 • IEEE 802.16e-2005 • Mesh mode • PmP mode • Security analysis in IEEE 802.11a/b/g • Security development in IEEE 802.11i protocol • Development of security mechanism in a mesh network scenario PRIN Women

17. Security in computer networks • A firewall is a device that filters packets between two networks • It can be implemented in almost every device Router Packet filtering Parameters: IP address and socket number Distributed firewall: each device has all the rules PRIN Women

18. A Bloom filter is an abstract structure for representing a set of elements in a compact way in order to do queries exploiting hash tables principles A Bloom filter is represented in the memory with a m bit array At each elements of the generating set k independent hash functions (h1,h2,..., hk) are applied For each element x  S (with dim{S}=n), the resulting bit from the hash application are set to 1 The query are done by applying the same hash functions to the element to be analyzed and verifying that bit are set to 1 also in the filter 0 0 1 0 1 0 1 0 1 0 0 1 1 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 1 1 1 1 h1(x1),h2(x1) h1(x2),h2(x2) h1(y2),h2(y2) h1(y1),h2(y1) Bloom filters Disadvantage: possible positive false • Bloom filters in Forward chain • The rules define how t generate the filter; they are not inserted in the filter • Higher security: the security policy is hidden inside the filter • The filtere generator set is designed from the filtering parameters Design a filter from two elements x1≠x2 Verify if the elements y1 ≠ y2 ≠ x1≠ x2 belong to the filter Negative false are not possible Positive false PRIN Women

19. Security analysis of IEEE 802.16 • The authentication scheme used in Wimax, Privacy Key Management (PKM) has already been criticized for insecurities revealed in the authentication protocol. • Some of them have been addressed in the e amendment that become IEEE 802.16-2005. • Some insecurities have not been addressed and deal with: • authentication in mesh mode • management frames PRIN Women

20. Mesh authentication • NLE is used to avoid another multi-hop authentication, note that PMP authentication is a time consuming, certificate based authentication. • A→B: HMAC{OSS, frame number, A Node_ID, B Node_ID} • B→A: HMAC{OSS, frame number, B Node_ID, A Node_ID} • A→B: Accept, Random unused link ID PRIN Women

21. Security enhancement in IEEE 802.11i • Agents and protocols: • The Authentication Server (AS) is introduced • EAP-TLS • PMK moving • 4-way handshake, PTK generation • Security: • Solved problems in IEEE 802.11a/b/g • The session concept is introduced (PMKSA) • Not efficient in the ad-hoc mode PRIN Women

22. Development of a secure mesh network • Scenario: • Mesh network constituted of Access Point (AP) • Each AP manages an infrastructured network • The problem is to manage a secure handoff • Security requirements • Secure network against external attacks • Against the internal attacks there is: • Attack localization • Access control PRIN Women

23. Software & Tools • Development of a Cross-layer simulator based on IEEE 802.15e (OFDMA/TDD) scenario • MAC Layer • NS2 CMU Monarch Project • Scheduled access vs random access • PHY Layer (Outside this scope) • Channel variation & BER analysis (& other PHY layer characteristics…) • Based on C++ libraries developed by own • MuDiSP simulation tool PRIN Women

24. Publications • R. Fantacci and D. Tarchi, “Bridging Solutions for a Heterogeneous WiMAX-WiFi Scenario”, Journal of Communications and Networks, vol. 8, no. 4, pp. 369-377, Dec. 2006. • R. Fantacci, D. Tarchi and M. Bardazzi, “Performance Evaluation of the MAC Protocol in IEEE 802.16 Systems with Data and VoiP Traffic Scheduling”, submitted to Wiley Wirel. Commun. Mob. Comput. • D. Tarchi, R. Fantacci, and E. Bonciani,“Analysis and Comparison of Scheduling Techniques for a BWA OFDMA Mobile System”, submitted to Wiley Wirel. Commun. Mob. Comput. • R. Fantacci, D. Tarchi, and M. Bardazzi, “Quality of Service Management in IEEE 802.16 Wireless Metropolitan Area Networks”, in Proc. of IEEE ICC 2006, Istanbul, June 2006 • L. Maccari, R. Fantacci, T. Pecorella, and F. Frosali, “Secure, fast handhoff techniques for 802.1X based wireless network”, in Proc. of IEEE ICC 2006, Istanbul, June 2006 • D. Marabissi, D. Tarchi, F. Genovese, and R. Fantacci, “A Finite State Modeling for Adaptive Modulation in Wireless OFDMA Systems”, in Proc. of COST 289 4th Workshop, Apr. 2007, Gothenburg, Sweden • L. Maccari, R. Fantacci, P. Neira, and R. M. Gasca, “Mesh network firewalling with Bloom Filters”, Proc. of IEEE ICC 2007, Jun. 2007, Glasgow, United Kingdom • L. Maccari, M. Paoli, and R. Fantacci, “Security analysys of IEEE 802.16”, in Proc. of IEEE ICC 2007, Jun. 2007, Glasgow, United Kingdom • D. Marabissi, D. Tarchi, R. Fantacci, and F. Genovese, “Adaptive modulation algorithms based on finite state modeling in wireless OFDMA systems”, in Proc. of IEEE PIMRC 2007, Sep. 2007, Athens, Greece • D. Marabissi, D. Tarchi, F. Genovese, and R. Fantacci, “Adaptive Modulation in Wireless OFDMA Systems with Finite State Modeling”, in Proc. of IEEE Globecom '07, Nov. 2007, Washington, DC, USA • D. Tarchi, R. Fantacci, and E. Bonciani, “On the Ranging and Scheduling of Data Traffic in OFDMA Mobile Environments”, accepted for publication in Proc. of IEEE WCNC 2008. • D. Marabissi, D. Tarchi, A. Biagioni, and R. Fantacci, “Adaptive Subcarrier Allocation Algorithms in Wireless OFDMA Systems”, accepted for publication in Proc. of IEEE ICC 2008. • D. Marabissi, D. Tarchi, F. Balleri, and R. Fantacci, “Efficient Adaptive Modulation and Coding techniques for WiMAX systems”, accepted for publication in Proc. of IEEE ICC 2008. PRIN Women - 3rd Meeting