Performance comparison of selected wired and wireless Networks on Chip (NoC) architectures

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1 Performance comparison of selected wired and wireless Networks on Chip (NoC) architectures Maria Komar Tampere University of Technology, Tampere, Finland P.G. Demidov Yaroslavl State University, Yaroslavl, Russia

Komar Tampere University of Technology, Tampere,

Motivation for NoC : CPU development 1/12 Earlier: single core CPUs o Benefits: simple o Drawbacks: no possible improvement Nowadays: multicore concept o Benefits:

2 Motivation for NoC : CPU development 1/12 Earlier: single core CPUs o Benefits: simple o Drawbacks: no possible improvement Nowadays: multicore concept o Benefits: increase in performance o Drawbacks: inefficient data exchange, bad scalability Solution: Network on Chip (NoC) concept o Many computational elements on a single chip

Benefits: increase in performance o Drawbacks: inefficient data exchange, bad

(Wireless) Network on Chip 2/12 Major problem: connections between nodes o (De)multiplexing issues Idea: Wireless Network on Chip (WNoC) o Wires Wireless links Benefits:

3 (Wireless) Network on Chip 2/12 Major problem: connections between nodes o (De)multiplexing issues Idea: Wireless Network on Chip (WNoC) o Wires Wireless links Benefits: o Lack of bus connections o Multicasting, broadcasting Drawbacks: o Additional challenges (media access control, collision control, etc.) Comparison of NoC and WNoC needed

Benefits: o Lack of bus connections o Multicasting, broadcasting Drawbacks: o

4 Studied topologies 3/12 vs? NoC Benefits: o Simple o Reliable o Simple routing Drawbacks: o High delay WNoC Benefits: o Low delay Drawbacks: o MAC o Interference o Reliability

5 4/12 Research task vs? NoC WNoC Metric of interests: delay Delay time spent from the start of a message transmission up to successful message reception Extremely important for CPU performance

Wireless channel peculiarities (1) 5/12 For WNoC we use THz band (0.1-0.

6 Wireless channel peculiarities (1) 5/12 For WNoC we use THz band ( THz) THz 1 st transparency window of THz band Transparency window part of THz band, where molecular absorption noise is negligible Plot form the paper On the communication range and throughput of nanomachines in terahertz frequency band by P. Boronin, V. Petrov, D. Moltchanov, Y. Koucheryavy

54 THz 1 st transparency window of THz band Transparency window part of THz band, where

7 Antenna size, λ/2 Wireless channel peculiarities (2) 5/12 For WNoC we use THz band ( THz) o Channel capacity 5Tbps o Throughput for the simplest MCS 0,31Tbps o Antennas must be as small as possible 0,15 mm 1,5 mm 2,5 mm 1 THz 100 GHz 60 GHz THz band subthz band (mm waves) CPU size (1 dimension) 4 cm

54 THz) o Channel capacity 5Tbps o Throughput for the simplest MCS 0,31Tbps

8 Wired channel peculiarities 6/12 We used a bus with realistic characteristics According to this characteristics data packet transmission time was computed It takes 2 ns to transmit packet to the neighbor core Transmitted data packet size: 64 Byte for data + 8 Bytes for address

transmission time was computed It takes 2 ns to transmit packet to

9 NoC delay analysis 7/12 N number of nodes δ delay via single hop D delay D ( N 1) 4 2 N 4 ( N 1), N is odd, N is even

10 WNoC delay analysis 8/12 T s symbol duration, two different scenario o Obtained from channel capacity (minimum T s value) o Obtained using simple MCS (OOK) L addr address size (8 bytes) L data data block size (64 bytes) D delay D T s ( L L ) data addr

o Obtained using simple MCS (OOK) L addr address size (8

Numerical results: average delay 9/12 Wired system is useful for the small and medium number of cores (up to approximately 60) Wireless system is better for the high number of

11 Numerical results: average delay 9/12 Wired system is useful for the small and medium number of cores (up to approximately 60) Wireless system is better for the high number of cores (more, than approximately 60) For the extremely small number of cores wired system is better that all possible wireless system that were taken into account in this study

of cores (more, than approximately 60) For the extremely small number of cores wired

12 Numerical results: delay distribution 10/12 We take into account points, where delay is approximately equal for wires and wireless systems Delay in wireless system is more stable even for small number of cores Delay stability is very important for CPU design

wireless systems Delay in wireless system is more stable even

13 Summary 11/12 NoC and WNoC initial comparison was made in terms of delay According to our study o NoC is useful for small and medium number of cores o WNoC is useful for huge number of cores o Delay for WNoC is more stable Collisions, MAC, Interference, etc. were not taken into account

number of cores o WNoC is useful for huge number of cores o Delay for

14 12/12 Thank you for your attention! Maria Komar Tampere University of Technology, Tampere, Finland P.G. Demidov Yaroslavl State University, Yaroslavl, Russia

CROSS LAYER BASED MULTIPATH ROUTING FOR LOAD BALANCING

CHAPTER 6 CROSS LAYER BASED MULTIPATH ROUTING FOR LOAD BALANCING 6.1 INTRODUCTION The technical challenges in WMNs are load balancing, optimal routing, fairness, network auto-configuration and mobility