Pierre Achaichia - Contributions to the Improvement of Multiuser PLC Home Networks

Transcript

1. Contributions to the Improvement of Multiuser PLC Home networks unrestricted Pierre ACHAICHIA Pierre ACHAICHIA Pierre ACHAICHIA Pierre ACHAICHIA, October 12, Orange Labs Rennes Orange Labs Supervisors Marie Le BOT Pierre SIOHAN Supélec Supervisor Jacques PALICOT
2. 1. Motivations & Objectives 2. HomePlug Specifications Overview 3. The HPAV Modulation Scheme PHY PHY PHY PHY Outline INTRO INTRO INTRO INTRO unrestricted 4. Windowed OFDM vs OFDM/OQAM: Capacity Analysis 5. PLC Networks Multicast Issue 6. OFDMA for Point-to-Multipoint Transmissions 7. Conclusion MAC MAC MAC MAC 2 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
3. Motivations & Objectives unrestricted 3 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Motivations & Objectives
4. Increased data rates offered to customers (FTTH), more and more networking devices within the Home area, leading to: – Increased Number of QoS demanding Services – Heterogeneous traffic: services need to be prioritized – Wi-Fi technology cannot answer all use cases: network coverage, not necessarily appropriate to deliver QoS demanding applications like IPTV… Thesis Motivations unrestricted 4 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 like IPTV… Powerline Communication (PLC) benefits: – "No new wire" and easy to access network – Quasi-static channels allowing fine link adaptation – Increased home network coverage and reliability – Low interference between neighboring networks FTTH: Fiber To The Home QoS: Quality of Service IPTV: IP Television
5. Thesis Objectives At the PHY layer: Bandwidth extension up to 100 MHz Show benefits of the OFDM/OQAM modulation for next-generation PLC networks Anticipate evolution of broadband PLC networks unrestricted 5 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 At the MAC layer: Identify lacks of current PLC standards (HPAV-based) Propose novel allocation techniques to improve network efficiency in a multi user context PHY: Physical MAC: Medium Access Control
6. HomePlug unrestricted 6 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Specifications Overview
7. A Little Background… The home power grid is a harsh communication medium: Multi-path channels due to impedance mismatch, resulting in reflection signals Quasi-static nature Severe attenuation, typically comprised between 20 and 60 dB unrestricted 7 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Various interference sources: • Colored background noise • Impulsive noise sources: home appliances, such as hair dryer, vacuum cleaner… Error bursts
8. • Windowed OFDM modulation in the [1.8; 30] MHz frequency range: 3072-point FTT size, 917 active subcarriers, up to 200 Mbps PHY rate • Fine channel adaption through the definition of tone maps (bit-loading) -> BPSK to 1024-QAM, various FEC rates, GI… • Beacon-based synchronization, controlled by a CCo (Central Coordinator), providing scheduled channel accesses (TDMA) HomePlug Specifications Evolution of Broadband PLC Specifications Capacity • OFDM modulation in the [4; 21] MHz frequency range • CSMA/CA : Distributed and prioritized channel Access, error detection and • Uses HPAV as baseline technology • Introduction of an ISP protocol to handle dual-PHY • Bandwidth extension up to 50 MHz (4096-point FFT), possibility to use 4096-QAM • Up to 500 Mbps PHY rate Bandwidth extension up to 86 MHz (8192-point FFT), combined with MIMO PLC Between 750 Mbps and 1.5 Gbps PHY rates, fully compliant with P1901 standard 1.5 1.5 1.5 1.5 Gbps Gbps Gbps Gbps unrestricted • Coexistence with HP 1.0 devices, but not backward compatible! 8 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 OFDM: Orthogonal Frequency Division Multiplexing CSMA/CA: Carrier Sense Multiple Access/Collision Avoidance FFT: Fast Fourier Transform BPSK: Binary Phase Shift Keying QAM: Quadrature Amplitude Modulation Years channel Access, error detection and Automatic Repeat Request (ARQ) mechanisms • Up to 14 Mbps PHY rate, further enhanced by Intellon with the proprietary HP 1.0 turbo • Up to 500 Mbps PHY rate FEC: Forward Error Correction TDMA: Time Division Multiple Access IEEE: Institute of Electrical and Electronics Engineers ISP: Inter System Protocol MIMO: Multiple Input Multiple Output 14 14 14 14 Mbps Mbps Mbps Mbps 200 200 200 200 Mbps Mbps Mbps Mbps 500 500 500 500 Mbps Mbps Mbps Mbps 2001: HP 1.0 2001: HP 1.0 2001: HP 1.0 2001: HP 1.0 2005: HPAV 1 2005: HPAV 1 2005: HPAV 1 2005: HPAV 1 2010: IEEE P1901 2010: IEEE P1901 2010: IEEE P1901 2010: IEEE P1901 2012: HPAV 2 2012: HPAV 2 2012: HPAV 2 2012: HPAV 2
9. The HPAV unrestricted 9 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Modulation Scheme
10. OFDM principles Multicarrier modulations are the appropriate answer to cope with the multipath nature of PLC channels Attenuation unrestricted 10 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 f f f fmin min min min f f f fmax max max max Frequency
11. OFDM principles Multicarrier modulations are the appropriate answer to cope with the multipath nature of PLC channels – OFDM: Orthogonal Frequency Division Multiplexing unrestricted 11 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 T0 (FFT Size) t T0 (FFT Size) t ISI+ICI t CHANNEL CHANNEL CHANNEL CHANNEL ISI: Inter-symbol Interference ICI: Inter-Carrier Interference
12. OFDM principles Multicarrier modulations are the appropriate answer to cope with the multipath nature of PLC channels – CP-OFDM: OFDM with Cyclic prefix unrestricted 12 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 t ISI+ICI t CHANNEL CHANNEL CHANNEL CHANNEL T0 GI T0 GI T0 GI t T0 GI T0 GI T0 GI ISI+ICI free GI: Guard Interval
13. OFDM principles CP-OFDM allows interference-free transmissions, thanks to the addition of a guard interval (counterpart: loss loss loss loss in the spectral in the spectral in the spectral in the spectral efficiency efficiency efficiency efficiency) However However However However, PLC equipments must comply with a restrictive spectral mask unrestricted 13 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Because of the bad spectral containment of the subcarriers,the classic CP CP CP CP- - - -OFDM OFDM OFDM OFDM scheme is not not not not suited suited suited suited for broadband PLC
14. The Windowed OFDM Modulation To improve the spectral containment of the subcarriers, HPAV introduces a Windowed OFDM modulation scheme Windowed OFDM Pulse-Shaped OFDM unrestricted 14 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Same Same Same Same spectral efficiency as CP-OFDM: RI: Roll-off Interval
15. The Windowed OFDM Modulation However However However However, , , , looking at the receiver side: unrestricted 15 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Problem Problem Problem Problem: : : : in strongly dispersive channels, an interference term remains present in the demodulated symbol The effective protection effective protection effective protection effective protection against interference is reduced reduced reduced reduced in proportion of the RI effective GI = GI effective GI = GI effective GI = GI effective GI = GI- - - -RI RI RI RI remaining interference
16. Link Adapation Broadband PLC specifications allow to adapt the signal to the transmission path, using bit-loading techniques: Signal to Signal to Signal to Signal to Interference Interference Interference Interference plus Noise Ratio plus Noise Ratio plus Noise Ratio plus Noise Ratio Noise variance Complex QAM symbol variance ISI+ICI power Channel Coefficient unrestricted 16 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 SINR gap: Capacity Capacity Capacity Capacity formula formula formula formula Tone Tone Tone Tone map map map map Ex: in HPAV, SER: Symbol Error Rate
17. Broadband PLC specifications allow to adapt the signal to the transmission path, using bit-loading techniques: – Ex. : HPAV OFDM bit-loading (917 subcarriers, [1.8: 30] MHz) Each tone map: • is defined on a specific link • is defined for a one-way communication Link Adapation Channel frequency response Dedicated Tone Map (TM) unrestricted 17 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Allows to approach the theoretical capacity of the channel
18. Windowed OFDM vs OFDM/OQAM: unrestricted 18 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 OFDM/OQAM: Capacity Analysis
19. OQAM: Offset Quadrature Amplitude Modulation Multicarrier Modulation with frequency spacing F0 As classic OFDM systems, FFT-based implementation is possible Main Main Main Main principle principle principle principle: The transmissions of the real and imaginary parts of the complex The OFDM/OQAM Modulation unrestricted The transmissions of the real and imaginary parts of the complex symbols cm,n are delayed of one half symbol duration T0 /2 The constraint is to keep a phase shift of π/2 between adjacent symbols in time and frequency 19 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 T0 (FFT Size) t T0 (FFT Size) t Re{cm,n } Im{cm,n } Classic Classic Classic Classic OFDM OFDM OFDM OFDM OFDM/OQAM OFDM/OQAM OFDM/OQAM OFDM/OQAM real or imaginary part of cm,n prototype filter Phase term T0 /2
20. Main Main Main Main benefits benefits benefits benefits: : : : No GI same spectral efficiency as OFDM without CP with lower interference Relaxing the orthogonality constraint by only imposing it in the real field gives an additional degree of freedom to shape transmitted symbols For a distortion-free channel, the interference only affects the The OFDM/OQAM Modulation unrestricted For a distortion-free channel, the interference only affects the imaginary part of the symbols, and is therefore removed by the real-part extraction For a realistic channel, it can be well contained if the prototype filter is appropriately selected, and using a 3-tap (ASCET [Alhava et al., 2001]) Zero Forcing (ZF) equalizer 20 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 ASCET: Adaptive Sine/Cosine-modulated filter bank Equalizer for Transmultiplexer
21. How can we efficiently exploit the additional degree of freedom offered by OQAM in the particular context of PLC? Ex.: comparison between a prototype filter optimized upon the FS (Freq. Selectivity) criterion and the HPAV window The OFDM/OQAM Modulation unrestricted 21 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
22. How can we efficiently exploit the additional degree of freedom offered by OQAM in the particular context of PLC? The association of OFDM/OQAM with frequency selective filters allows to activate more than 917 subcarriers (windowed OFDM) FCC mask: windowed OFDM: 917 active subcarriers OFDM/OQAM + FS4: 968 active subcarriers The OFDM/OQAM Modulation unrestricted OFDM/OQAM + FS4: 968 active subcarriers CENELEC mask (draft standard) windowed OFDM: [503, 767] active subcarriers OFDM/OQAM + FS4: [632, 871] active subcarriers 22 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 FCC: Federal Communications Commission CENELEC: Comité Européen de Normalisation
23. Simulation parameters for the capacity analysis: 3 classes of PLC channels (Class 2, 5 and 9) [Tlich et al., 2010] with: Capacity (class 9)>Capacity(class 5)>Capacity(class 2) 100 channel realizations Colored background noise [Omega D3.2, 2010] Target SER=10-2 Windowed OFDM vs OFDM/OQAM: HPAV 1 Context unrestricted Target SER=10-2 FCC spectral mask: • 917 active subcarriers for windowed OFDM • 968 active subcarriers for OFDM/OQAM ZF per-channel equalizers: • 1-tap for windowed OFDM • 3-tap (ASCET) for OFDM/OQAM 23 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
24. Some results on class 9 channels (transmitted PSD is increased from -120 to -50 dBm/Hz ): Windowed OFDM vs OFDM/OQAM: HPAV 1 Context Transmission capacity (infinite granularity) unrestricted 24 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Achievable throughput (finite granularity) PSD: Power Spectral Density
25. How can we efficiently increase the capacity of PLC networks? Bandwidth extension: in the scope of OMEGA, simulations were conducted in the [1,8: 87.5] MHz bandwidth (~AV2) (3072 8192- point FFT) Enable higher modulation orders: the 4096-QAM (12 bits) is allowed by AV 2 Number of active subcarriers: Windowed OFDM vs OFDM/OQAM: HPAV 2 Context unrestricted Number of active subcarriers: • Windowed OFDM : 917 (HPAV) + 2428 = 3354 • OFDM/OQAM : 968 (HPAV) + 2440 = 3408 25 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
26. Some results on class 9 channels (transmitted PSD is increased from -120 to -50/-80 dBm/Hz ): Windowed OFDM vs OFDM/OQAM: HPAV 2 Context Transmission capacity (infinite granularity) unrestricted 26 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Achievable throughput (finite granularity)
27. Some results on class 2 channels (transmitted PSD is increased from -120 to -50/-80 dBm/Hz ): Windowed OFDM vs OFDM/OQAM: HPAV 2 Context Transmission capacity (infinite granularity) unrestricted 27 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Achievable throughput (finite granularity)
28. HPAV 1 context: a significant throughput gain can be achieved by OFDM/OQAM using a frequency selective prototype filter, together with a 3-tap equalizer (ASCET) Up to 20 % increase in the data rates using the FCC mask More than 40 % increase is shown considering the new CENELEC mask (cf. dissertation) HPAV 2 context: The OMEGA project has shown that Next- PHY Layer Contributions Summary unrestricted HPAV 2 context: The OMEGA project has shown that Next- generation PLC networks(HPAV 2) could reach the Gbps connectivity, thanks to the bandwidth extension (+MIMO) Main Contributions Main Contributions Main Contributions Main Contributions (cf. dissertation): Computation of the analytical expression of the interference term of the Windowed OFDM signal Generalized expression of the OFDM/OQAM interference power, analytical expression of the noise power at the output of ASCET 28 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
29. Multicast Issue in PLC unrestricted 29 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Networks
30. Multicast Issue Broadband PLC specifications allow to adapt the signal to the transmission path, using bit-loading techniques However However However However, a problem arises if we want to simultaneously reach several stations Tone maps allow to approach the theoretical capacity of the channel. unrestricted 30 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 HPAV / IEEE P1901: HPAV / IEEE P1901: HPAV / IEEE P1901: HPAV / IEEE P1901: Multicast/broadcast services must be handled as multiple unicast streams (unicast conversion) Stations are Stations are Stations are Stations are isolated isolated isolated isolated from from from from one one one one another another another another
31. Known solution: LCG (Lowest Channel gain) Computation of an equivalent channel among the K stations to reach In PLC networks, LCG can be directly applied at the transmitter side by computing a multicast tone map: LCG Solution unrestricted Ex: K = 4 HPAV 2 tone maps 31 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
32. Is LCG always better than the Unicast Conversion? From the PHY layer point of view: YES • Study conducted for the HPAV TWG (measured PLC channels in 3 countries): LCG Solution unrestricted However However However However, , , , from the MAC layer point of view: not necessarily 32 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 HPAV TWG: HPAV Technical Working Group
33. If we want each one of the K adressed stations to acknowledge the Multicast transmission: LCG Solution LCG LCG LCG LCG can can can can degrade degrade degrade degrade the MAC the MAC the MAC the MAC efficiency efficiency efficiency efficiency Unicast transmission Unicast transmission Unicast transmission Unicast transmission The transmission window is limited to 2.5 ms unrestricted 33 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Unicast transmission Unicast transmission Unicast transmission Unicast transmission Multicast transmission Multicast transmission Multicast transmission Multicast transmission The K 1 additional ACK frames must be taken into account MAC MAC MAC MAC efficiency efficiency efficiency efficiency decreases decreases decreases decreases as as as as K K K K increases increases increases increases
34. Idea Idea Idea Idea: Instead of defining a unique "multicast" tone map, the K K K K stations are classified into N N N N multicast subsets Each multicast subset is associated with an exclusive multicast tone map, contructed by applying the LCG principle among the tone maps contained in the subset A tradeoff must be made between the number of simultaneously Smart Merging Approach unrestricted A tradeoff must be made between the number of simultaneously addressed stations and the transmission window length A smart merging algorithm has been developped (cf. manuscript), considering both PHY and MAC layers: Assessing the correlation between tone maps before merging them Taking into account the reduction of the transmission window 34 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
35. Multicast tone maps allow major improvement of the transmission efficiency (cf. manuscript and the study conducted for the HPAV TWG) However However However However, special care must be taken when considering the MAC overhead: If we want the K adressed stations to acknowledge the frame, the transmission window is reduced Multicast Summary unrestricted transmission window is reduced The creation multiple multicast subsets may be more appropriate in such a case Complementary studies need to be made to assess: The multiple overhead sources: frame headers, segmentation, inter- frame spaces… The impact on system complexity and reactivity 35 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
36. OFDMA for Point-to-Multipoint unrestricted 36 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Point-to-Multipoint Transmissions
37. The Interest of Point-to-Multipoint STA 3: Bridge to STA 1: Bridge to set- unrestricted If More than 2 Stations in the network: Point-to-multipoint transmissions = Frequent use case 37 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Bridge to computer 1 Bridge to set- top box 1 STA 0 (CCo): Bridge to Home GW STA 2: Bridge to set- top box 2 Distant Services Home GW: Home Gateway
38. STA 3: Bridge to computer 1 STA 1: Bridge to set- top box 1 Taking advantage of the Multiuser Diversity unrestricted 38 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 STA 2: Bridge to set- top box 2 Distant Services STA 0 (CCo): Bridge to Home GW PLC channels have a multi-path nature, and are quasi-static: Bit-loading algorithms result in the creation of tone maps, specific to each link Home GW: Home Gateway
39. Taking advantage of the Multiuser Diversity unrestricted How can we take advantage of this multiuser diversity? OFDMA: OFDMA: OFDMA: OFDMA: distribution of the M M M M subcarriers subcarriers subcarriers subcarriers among among among among the K the K the K the K users users users users 39 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 OFDMA: Orthogonal Frequency Division Multiple Access
40. If we apply the σ permutation s.t.: increases increases increases increases on {1,..,M} How can we optimally orthogonalize tone maps? Ex.: K = 2 K = 2 K = 2 K = 2 tone maps to orthogonalize The Tone Maps Orthogonalization Problem unrestricted with: and 40 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
41. How can we optimally orthogonalize tone maps? K = 3 K = 3 K = 3 K = 3 ? The Tone Maps Orthogonalization Problem Problem: If K>2 If K>2 If K>2 If K>2, Finding a concave capacity region is far from being straightforward unrestricted 41 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 2 solutions were developped: A low-cost, nearly-optimal algorithm: TMSA TMSA TMSA TMSA (Tone Maps Splitting Algorithm) An optimal resolution based on a geometrical approach of the problem region is far from being straightforward
42. Geometrical approach: Allocation Allocation Allocation Allocation vector vector vector vector: : : : Capacity Capacity Capacity Capacity balance: balance: balance: balance: The Tone Maps Orthogonalization Problem unrestricted 42 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 The Tone Tone Tone Tone maps maps maps maps orthogonalisation orthogonalisation orthogonalisation orthogonalisation problem problem problem problem comes down to maximize maximize maximize maximize , a K-dimentionnal vector directed directed directed directed by FDM: Frequency Division Multiplexing
43. Geometrical approach: K = 3 Noticing that the projection of the optimal allocation vector onto the plane P2 , defined by vectors and is colinear to Starting from K = 2: K = 2: K = 2: K = 2: The Tone Maps Orthogonalization Problem unrestricted We extend the problem to K = 3 K = 3 K = 3 K = 3 to create 43 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Starting with the optimal allocation optimal allocation optimal allocation optimal allocation vector vector vector vector between links 1 links 1 links 1 links 1 and 2 2 2 2, Maximizing Maximizing Maximizing Maximizing comes down to reallocate reallocate reallocate reallocate subcarriers subcarriers subcarriers subcarriers maximizing maximizing maximizing maximizing the component component component component along basis vector , while minimizing minimizing minimizing minimizing the the the the cost cost cost cost on
44. Geometrical approach: K = 3 Intitialization: What is the loss on after allocating a capacity ε on link 3 ? The Tone Maps Orthogonalization Problem unrestricted 44 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
45. Geometrical approach: K = 3 Intitialization: What is the loss on after allocating a capacity ε on link 3 ? The Tone Maps Orthogonalization Problem unrestricted C2 increases with β2 , while C1 decreases with β2 By always choosing the subcarrier ensuring the minimal loss on , we maximize 45 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
46. Geometrical approach: K > 3 For K = 4, we can establish the following cost functions: The Tone Maps Orthogonalization Problem unrestricted with and 46 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
47. Geometrical approach: K > 3 From which we deduce a general expression of the cost function, for any K > 3. In the plane PK 1 , the cost on link n is expressed as follows: The Tone Maps Orthogonalization Problem unrestricted with and 47 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12
48. Point-to-Multipoint Summary The tone maps orthogonalization problem has been set and solved using a geometrical approach However However However However, this method remains too complex to be incorporated in real PLC systems. A fast orthogonalization algorithm has been then developed: the Tone Maps Splitting Algorithm (TMSA) TMSA has been integrated in a PLC network simulator, and we have proposed an HPAV-compliant OFDMA access scheme: unrestricted 48 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 have proposed an HPAV-compliant OFDMA access scheme: 20% to 30 % improvement of the data rates will generally be achieved using OFDMA (P1901, saturated throughput) In future HPAV 2.0 systems, as the number of subcarriers will be increased, so will be the multiuser diversity Better gains have to be expected in the future
49. Conclusion unrestricted 49 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Conclusion
50. Main Contributions: Main Contributions: Main Contributions: Main Contributions: On the PHY layer: On the PHY layer: On the PHY layer: On the PHY layer: • Within the OMEGA project, we have shown that PLC systems could benefit from a substantial troughput gain, by increasing the bandwidth (up to 87.5 MHz for OMEGA, 86 MHz for AV 2) • However However However However, another modulation scheme than windowed OFDM, called OFDM/OQAM, can further enhanced this capacity Conclusion unrestricted 50 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 called OFDM/OQAM, can further enhanced this capacity improvement • Thanks to the assocation of OFDM/OQAM with prototype filters optimized upon the FS criterion, it is possible to activate more tones while still complying with the spectral mask • Considering the CENELEC draft standard, the performance gap between the two modulation schemes will be even more important
51. Main Contributions: Main Contributions: Main Contributions: Main Contributions: On the MAC layer: On the MAC layer: On the MAC layer: On the MAC layer: • Since the release of the IEEE P1901 standard in 2010, the field of broadband PLC has stabilized • Yet Yet Yet Yet this thesis shows that current systems could still benefit from significant improvement The multicast issue The multicast issue The multicast issue The multicast issue has been firstly adressed, where we Conclusion unrestricted 51 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 The multicast issue The multicast issue The multicast issue The multicast issue has been firstly adressed, where we have shown that the definition of multicast tone maps could bring major improvement in the data rates Point Point Point Point- - - -to to to to- - - -multipoint multipoint multipoint multipoint transmissions have been then studied. In this work, we emphasize on the fact that the fine link adaptation could be better exploited by defining an OFDMA access mode
52. Contributions Conference papers – P. Achaichia, M. Le Bot, P. Siohan, "Windowed OFDM versus OFDM/OQAM: A Transmission Capacity Comparison in the HomePlug AV Context," International Symposium on Power Line Communications , ISPLC 2011, Udine, Italy, April 2011. – P. Achaichia, M. Le Bot, P. Siohan, " An Efficient Technique for Merging Transmissions in a Multicarrier Context ", IWCLD 2011, Rennes, France, November 2011. unrestricted 52 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 November 2011. – P. Achaichia, M. Le Bot, P. Siohan, "Frequency Division Multiplexing Analysis for Point-to-Multipoint Transmissions in Power Line Networks," International Symposium on Power Line Communications , ISPLC 2011, Udine, Italy, April 2011. – P. Achaichia, M. Le Bot, P. Siohan, " Point-to-Multipoint Communication in Power Line Networks: A Novel FDM Access Method", ICC 2012, Ottawa, Canada, June 2012. – P. Achaichia, M. Le Bot, P. Siohan, ``Impact of CENELEC Transmission Spectrum Mask on Current PLC networks,'' to be submitted, 2012.
53. Contributions Journal papers – P. Achaichia, M. Le Bot, P. Siohan, ``OFDM/OQAM: A Solution to Efficiently Increase the Capacity of Future PLC Networks,'' Power Delivery, IEEE Transactions on, vol. 26, no. 4, pp. 2443-2455, Oct. 2011. – P. Achaichia, M. Le Bot, P. Siohan, ``Adrdessing the issue of FDM Resource Allocation for Point-to-Multipoint Communication in PLC Networks'' to be submitted, 2012. unrestricted 53 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 Patents – P. Achaichia, M. Le Bot, P. Siohan, ``Procédé de regroupement de stations pour optimiser la diffusion d'un flux multicast/broadcast,'' 2011. – P. Achaichia, M. Le Bot, P. Siohan, ``Procédé de distribution des sous-porteuses d'un système multiporteuse entre différents liens de communication,'' 2011.
54. Contributions Technical Contributions – A. Tonello, S. D'Alessandro, M. Antoniali, M. Biondi, F. Versolatto, A. Maiga, J.-Y. Baudais, F. S. Muhammad, P. Siohan, M. L. Bot, H. Lin, P. Achaichia, G. Ndo, G. Mijic, B. Cerato, S. Drakul, E. Viterbo et O. Isson, " Performance report of optimized PHY algorithms ", rap. tech., projet OMEGA, June 2010. – P. Achaichia, M. Le Bot, P. Siohan, "Multicast Tone Maps: Gains to Expect," HPAV face-to-face meeting, Lannion, March 2012. unrestricted 54 Pierre Achaichia - Contributions to the Improvement of Mulltiuser PLC Home Networks – 10/12/12 – P. Achaichia, M. Le Bot, P. Siohan, "FDM to Improve Point-to-Multipoint Communications in Powerline Networks", HPAV face-to-face meeting, Lannion, March 2012. – P. Achaichia, M. Le Bot, P. Siohan and P.Pagani, "Multicast Tone Maps Performance on Measured PLC Channels", HPAV TWG, April 2012. – P. Achaichia, M. Le Bot, P. Siohan and P.Pagani, "Multicast Communications: Practical Use Cases", HPAV TWG, May 2012.
55. Thank you. unrestricted Questions?