1 / 30

“A dynamic rate allocation technique for wireless communication systems”

“A dynamic rate allocation technique for wireless communication systems”. Romano Fantacci Full Professor Francesco Chiti Ph.D. Daniele Tarchi Ph.D. Department of Electronics and Telecommunications University of Florence Via di S. Marta, 3 I-50139 Florence, ITALY

saman
Download Presentation

“A dynamic rate allocation technique for wireless communication systems”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. “A dynamic rate allocation technique for wireless communication systems” Romano Fantacci Full Professor Francesco Chiti Ph.D. Daniele Tarchi Ph.D. Department of Electronics and Telecommunications University of Florence Via di S. Marta, 3 I-50139 Florence, ITALY E-mail: {fantacci,chiti,tarchi}@lenst.det.unifi.it

  2. Outline • Motivations • 3G systems features • UMTS-HSDPA • ALC Protocol Proposal • Physical channel • Proposed rate allocation protocol • System block diagram • Traffic sources • Overall Markov model • Analytical model • Numerical Results • N(), T() theoretical and simulated • Gain • Conclusions and further developments

  3. 1. Motivations Future wireless networks features • Global coverage by means of: • Efficient internetworking with existing wireless and wired standards by resorting to a cooperative approach rather than competitive • High mobility and variable traffic load management through dynamic Radio Resource Management policies (RRM): • cell planning • system reconfiguration • Services integration • Multimedia traffics with real time (voice, audio/video streaming) and data (Web services, Data Base queries) applications • Different Quality of Service (QoS) requirements (bandwidth, error rate, delays) • Asymmetric connections handling

  4. 144 Kbps 500 Km/h 384 Kbps 120 Km/h 2 Mbps 10 Km/h 1. Motivations Universal Mobile Telecommunications System UMTS/HSDPA cdma2000/1xEVDO IEEE802.11x TETRA2

  5. 1. Motivations High Speed Downlink Packet Access 3GPPRelease 5 (2001) arranges a further downlink access scheme to handle asymmetric, high bit rate, bursty data services in an indoor environment. This purpose could be achieved by, eventually, joint selection of the following strategies: • Adaptive Modulation and Coding (AMC) schemes • Hybrid Automatic Repeat reQuest (H-ARQ) techniques • Fast scheduling algorithms • Multiple Inputs Multiple Outputs (MIMO) channel modelling • Fast Cell Selection (FCS) algorithms Constraints: • Peak bit rate up to 10 Mbs • No QoS degradation

  6. I II III 2. ALC Protocol Proposal Modulation and Coding Schemes

  7. BAD GOOD GOOD BAD 2. ALC Protocol Proposal Physical Channel Model

  8. 2. ALC Protocol Proposal Physical Channel Model Exponential (memoryless) hypothesis [Gupta84] Tgood,Tbad: exponentially distributed PT : threshold power level PR : average received power level

  9. Bad 0 Good 1 • channel transition probability between i state and j state within a slot: • exponentially (geometrically) distributed • mean value related toreceived signal poweranduser mobility 2. ALC Protocol Proposal Physical Channel Model Discrete Memoryless Channel (DMC)

  10. 2. ALC Protocol Proposal Proposed Protocol • Base Station (BS) manages downlink streams according to a FIFO scheduling policy • Whenever an End User (EU) is selected, BS discretely monitors EU physical channel conditions • Depending on channel state, a proper AMC scheme is chosen • BS allocates to this EU both: • Dedicated Physical Channel (DPCH) • Downlink Shared Channel (DSCH) with a variable shared capacity

  11. 2. ALC Protocol Proposal Proposed Protocol System Block Diagram (uplink/downlink)

  12. 2. ALC Protocol Proposal System Model Traffic Sources • Poisson packet arrivals • Poisson message arrivals: • Modified Geometricdistribution of packet within each message • Paretomessage length (constant length packets): simplified Web traffic • Paretopacket length and Exponential packet inter-arrivals:real Web traffic) 3. approaches 2. in the presence of an high capacity CN connection

  13. k packets arrival probability within a slot 2. ALC Protocol Proposal System Model Traffic Sources • Poisson packet arrivals: • Batchmessage arrivals • Geometrical message length: • Pareto message length:

  14. 2. ALC Protocol Proposal System Model DT Embedded Markov chain model [Neuts89] Vectorial state (i,j): • i : status of the transmission channel • j : number of packets in the queue

  15. 2. ALC Protocol Proposal System Model Steady State Equations probability of being in i phase with j queued packets probability of having k packets arrivals

  16. arrival generating function average queued packets average queuing time (by Little formula) 2. ALC Protocol Proposal System Model Transformed Domain Equations

  17. 3. Numerical Results Operative Assumptions • 3GPP standard compliant: • IPv6 fast backbone: • maximum message length equal to 5 MB (truncated Pareto pdf) • packet length equal to 1.5 KB • Time slot (TTI) equal to 2 ms • Bit rate equal to 1.92 Mbps • Worst case multipath fading: and r01 = r10 = 0.2 (duty cycle = 0.5) • Infinite shared memory buffer length: no dropping effect • ARQ policy belonging to GB class (RTT<TTI) • Poutage equal to 5%

  18. 3. STF 179 Proposal NePSi: a Network Protocol Simulator • NePSi (Network Protocol Simulator) is a Discrete Event Simulator • It is based on C++ programming language • Object oriented programming is used in order to model different entities in the system • S. Nannicini, T. Pecorella, L. S. Ronga, “IneSiS: Integrated Network Protocols and Signal Processing Simulator”, Sixth Baiona Workshop 1999, Vigo, Spain. • Available at http://lenst.det.unifi.it/INeSiS/ under GNU License.

  19. Poisson packet arrival: 3. Numerical Results HSDPA Gain: improvingtransport bit rate ornetwork capacity(QoS) or decreasing on board device complexity

  20. Poisson packet arrival: 3. Numerical Results HSDPA Gain: loweringexpected delay (QoS)

  21. Poisson packet arrival: 3. Numerical Results Moderate impact on protocol efficiency

  22. Geometrical Batch message arrival: 3. Numerical Results

  23. Pareto Batch message arrival (3GPP): 3. Numerical Results

  24. Traffic models comparison: 3. Numerical Results Increasing HSDPA Gain along with traffic burstiness

  25. 3. Numerical Results Traffic models comparison: N and ak are statically similar: few queued messages (protocol efficiency)

  26. Poisson packet arrival: 3. Numerical Results ARQ protocols less affect HSDPA performance

  27. 4. Conclusion & developments Conclusion • High QoS applications (high bit rate, time sensitiveness) feasibility within 3G networks has been investigated • Following 3GPP recommendations, as to novel HSDPA scheme, a new protocol has been proposed • Based on physical channel state observation, a dynamic bandwidth is allocated to users • Protocol efficiency has been tested under several traffic models, including Web services models (LRD) • A remarkable gain has been highlighted, if compared with M/D/1 systems

  28. 4. Conclusion & developments Further Developments More accurate channel monitoring (3 MCS allocation) • State 0: 4-QAM, Rc=1/2 • State 1: 16-QAM, Rc=1/2 • State 2: 64-QAM, Rc=1/2

  29. 4. Conclusion & developments Enhanced Link Adaptation Algorithm Steady State Equations (3 states)

  30. 4. Conclusion & developments Publications[1]F. Chiti, L. Caponi, R. Fantacci: “Dynamic Bandwidth Allocation in Wireless Communications Systems”, in Proc. of AIRO 2002.[2] F. Chiti, L. Caponi, R. Fantacci: “An Efficient Rate Allocation Technique based on Channel Status Observation for Wireless Communication Systems”,in Proc. of IEEE WCNC 2004.[3]F. Chiti, L. Caponi, R. Fantacci:“A Dynamic Rate Allocation Technique for Wireless Communication Systems”,in Proc. of IEEE ICC 2004.[4]F. Chiti, L. Caponi, R. Fantacci: “A Dynamic Radio Resources Allocation Technique for Wireless Communication Systems”, submitted to Trans. on Vehic. Tech.Founded Research ProjectsETSI STF 179 on TETRA Release 2 TEDS Adaptive Link Control

More Related