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TECHNICAL UNIVERSITY OF CRETE DEPARTMENT OF ELECTRONICS & COMPUTER ENGINEERING

TECHNICAL UNIVERSITY OF CRETE DEPARTMENT OF ELECTRONICS & COMPUTER ENGINEERING Laboratories of Telecommunications and Information & Computer Networks. THESIS TITLE “Energy-Conserving Access Protocols for Transmitting Data in Unicast and Broadcast Mode” Papadimitriou Ioannis

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TECHNICAL UNIVERSITY OF CRETE DEPARTMENT OF ELECTRONICS & COMPUTER ENGINEERING

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  1. TECHNICAL UNIVERSITY OF CRETE DEPARTMENT OF ELECTRONICS & COMPUTER ENGINEERING Laboratories of Telecommunications and Information & Computer Networks THESIS TITLE “Energy-Conserving Access Protocols for Transmitting Data in Unicast and Broadcast Mode” Papadimitriou Ioannis Supervisor : Prof. Paterakis Michael Select Committee : Prof. Maras Andreas Prof. Triantafyllou Panagiotis

  2. 1. Introduction 1 / 1 • AIDC (Automatic Identification & Data Capture) systems • ·    Very large number of tags • ·    Small-size and low-cost tags • Repeated recharge/replacement of battery not feasible  Problem of energy saving

  3. 2. Problem Definition 1 / 1 Unicast/Broadcast packets from base station to tags Requirements : ·Minimization of packet delays ·Energy conservation Approach : ·Wake-up schedule at tags (“pseudo-random”) ·Transmission (of packets) scheduling strategy

  4. 3. Metrics 1 / 1 • ·Average total (Unicast/Broadcast) packet delay E(D) • ·Quotient of standard deviation to average total • (Unicast/Broadcast) packet delay σD / E(D) • ·Throughput of an algorithm • (Maximum arrival rate of packets λmax)

  5. 4. Broadcasting Case 1 / 6 Algorithms’ description : A) FCFS (First Come First Served) · Examination of packets according to their “age” · Worst performing algorithm – Wasted slots · Analytical performance evaluation B) FCFS-NES (First Come First Served with No Empty Slots) · No wasted slots (examination of next packet)

  6. 4. Broadcasting Case 2 / 6 Algorithms’ description (cont’d) : C) MDFm (Most Destinations First)m · Examination of m oldest packets · Transmission of the one with most destinations awake · Better usage of each time slot D) (DxW)m · Examination of m oldest packets · Transmission of the one with maximum DxW, where D : number of packet’s destinations, W : the “age” of packet · Better usage of each time slot + fairness

  7. 4. Broadcasting Case 3 / 6 Algorithms’ description (cont’d) : E) P-MDFm andP-(DxW)m (Preemptive MDFm and(DxW)m) · Modified versions of MDFm and (DxW)m · While examining the m oldest packets, if one is found that can be transmitted to all tags that have not received it yet, then this packet is selected for transmission during the current slot · No additional delay for a packet that can be deleted from base station’s queue

  8. 4. Broadcasting Case 4 / 6 Experimental results: Average total packet delay (slots) vs. λ (packets/slot) Figure 4.1 (N=500 , p=0.3 λmax , FCFS = 0.051164 )

  9. 4. Broadcasting Case 5 / 6 Quotient of standard deviation to average total packet delay vs. λ (packets/slot) Throughput of an algorithm λmax (packets/slot) vs. p Experimental results (cont’d): Figure 4.2 Figure 4.3

  10. 4. Broadcasting Case 6 / 6 The parameter m: For the algorithms MDFm, (DxW)m, P- MDFm, and P- (DxW)m there is an optimum value of m for each value of λ (giving the minimum average total delay), which increases with λ. (Table 4.1 : algorithm P-(DxW)m , maximum improvement 9%) Table 4.1

  11. 5. Mixed case Unicasting-Broadcasting 1 / 6 · Percentage of Broadcast packets higher than Unicast · Higher priority for Unicast packets · Uniform distribution for destinations of Unicast packets

  12. 5. Mixed case Unicasting-Broadcasting 2 / 6 Algorithms’ description : A) FCFS (First Come First Served) · Unicast/Broadcast packets stored in common buffer · Packets are examined according to their “age” · Worst performing algorithm – Wasted slots · Analytical performance evaluation B) FCFS-NES (First Come First Served with No Empty Slots) · Unicast/Broadcast packets stored in common buffer · No wasted slots (examination of next packet)

  13. 5. Mixed case Unicasting-Broadcasting 3 / 6 Algorithms’ description (cont’d) : C) 2L-(FCFS-NES) (Two Lists – First Come First Served with No Empty Slots) · Two different buffers for Unicast/Broadcast packets · Higher priority for Unicast packets · FCFS-NES algorithm is applied to Broadcast list of packets D) 2L-[P-(DxW)m] (Two Lists – Preemptive (DxW)m) · Two different buffers for Unicast/Broadcast packets · Higher priority for Unicast packets · P-(DxW)m algorithm is applied to Broadcast list of packets

  14. 5. Mixed case Unicasting-Broadcasting 4 / 6 Average total Unicast packet delay (slots) vs. λ (packets/slot) (Ν=500 , p=0.5 , Χ=0.3) Average total Broadcast packet delay (slots) vs. λ (packets/slot) Experimental results: Figure 5.1 Figure 5.2

  15. 5. Mixed case Unicasting-Broadcasting 5 / 6 Quotient of standard deviation to average total Broadcast packet delay vs. λ (packets/slot) Experimental results (cont’d): Quotient of standard deviation to average total Unicast packet delay vs. λ (packets/slot) Figure 5.3 Figure 5.4

  16. 5. Mixed case Unicasting-Broadcasting 6 / 6 Average total packet delay (slots) vs. λ (packets/slot) E(D)=X*E(Du)+(1-X)*E(Db) Throughput of an algorithm λmax (packets/slot) vs. (p , Χ) Experimental results (cont’d): Figure 5.5Figure 5.6

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