1. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Slide 1 Gains provided by multichannel transmissions Authors: Date: 2010-01-19

2. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Interests toward multi-channel Currently, the increase of bandwidth seems to be the only solution to increase the single user throughput. However, the probability of being allowed to transmit at 80MHz could be quite low in dense environment Interests of multi-channel –Multi-channel is an efficient solution to increase that probability and ensure an increase of single-user throughput compared to 11n. In [1], we proposed 3 different methods for multichannel transmissions

3. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Most favoured solution for multi-channel Non contiguous synchronous Aggregation of non contiguous channel wherever in the band –Only one CSMA-CA on the primary channel –Secondary, tertiary and quaternary can be on any channel of the band Primary Channel Secondary Channel time AIFS + backoff PIFS Ack Tertiary Channel time PIFSQuaternary Channel time PIFS SIFS 3030 2323 1717 Primary Secondary Tertiary Quaternary Ack

4. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Most favoured solution for multi-channel Non contiguous synchronous Without channel bonding within 80MHz With channel bonding within 80MHz Adj. BSS trans. Primary Channel Secondary Channel time AIFS + backoff Ack Tertiary Channel time PIFSQuaternary Channel time PIFS SIFS Adj. BSS trans. Primary Channel Secondary Channel time AIFS + backoff PIFS Ack Tertiary Channel time PIFSQuaternary Channel time PIFS SIFS Ack

5. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Most favoured solution for multi-channel Non contiguous synchronous Synchronous non contiguous implementation allows easy implementation of channel bonding Digital processing 5GHz 6GHz Transmitter I DAC IF RF DAC Segment 1 Segment 2 Seg 1 Busy channel Seg 1Seg 2 Seg 1

6. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Goal of this presentation Demonstrate the gains provided by multichannel to increase the probability to reach the desired bandwidth Clarify the advantages of multichannel transmissions  We ran some simulations for that purpose

7. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulation scenarios 30 23 56 52 48 44 4036 64 60 120116112108104100 128 124 132140 136 Simulate different load configurations on the whole 5GHz band –Select a number of busy channels among the 19 available in Europe: called density –Restrict the set of scenarios by setting a unique load for each busy channel (fixed to 0.3, 0.6 and 0.9) –For each density from 0 to 19, we simulate all possible configurations Example: density=8, load =0.3, one configuration among all possible

8. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulation scenarios Simulate different load configurations on the whole 5GHz band For each configuration, for each multichannel solution (non contiguous, bonding, nb of aggregated channels) and for each channel allocation, we calculate the equivalent bandwidth (bandwidth that you would be able to use 100% of the time) And select the best channel allocation and its corresponding optimal equivalent bandwidth Average the equivalent bandwidth for each density

9. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Calculation of the equivalent bandwidth Assume we have 4 aggregated channels, each with a specific probability Pi of being idle. We can calculate the probability to transmit at 20, 40, 60 or 80MHz P1, P2, P3, P4 Primary Without channel bonding P80 = P1*P2*P3*P4. P60 = P1*P2*P3*(1- P4) P40 = P1*P2*(1-P3) P20 = P1*(1-P2) With channel bonding P80 = P1*P2*P3*P4. P60 = P1*P2*P3*(1-P4) +P1*P3*P4*(1-P2) +P1*P2*P4*(1-P3) … P60

10. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Calculation of the equivalent bandwidth Assume we have 4 aggregated channels, each with a specific probability Pi of being idle. We can calculate the probability to transmit at 20, 40, 60 or 80MHz And calculate the equivalent bandwidth (bandwidth that you would be able to use 100% of the time) P1, P2, P3, P4 Primary

11. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulations Compare the equivalent bandwidth vs density for –Contiguous mode (with or without channel bonding) –Ideal synchronous non contiguous mode (with or without channel bonding) –Restricted* synchronous non contiguous mode (with or without channel bonding) * Restricted: only two non contiguous sets of contiguous channels Tested for different multichannel bandwidth (40, 60, 80MHz) Tested for different loads for busy channels: 0.3, 0.9 - 40MHz = 2*20MHz channels - 60MHz = 3*20MHz channels - 80MHz = 4*20MHz channels

12. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulation results: 80MHz, load=0.9 Significant improvements with ideal non contiguous Still very good gains with restricted non contiguous Importance of the channel bonding

13. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulation results: 80MHz, load=0.3 More compact results Still significative gains with restricted non contiguous Importance of the channel bonding

14. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Simulation results: Restricted non contiguous gains, load=0.9, 40MHz up to 80MHz Leads to a potential reduction of the bandwidth used by a BSS Example: Density 12, Eq bandwidth required 50MHz: - contiguous required used bandwidth: 80 MHz - non contiguous required used bandwidth: 60 MHz Example: Density 13, Eq bandwidth required 50MHz: - contiguous: saturated - non contiguous required used bandwidth: 60 MHz

15. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 Advantages of synchronous multi-channel (Conclusions) Clear increase of the probability to reach the desired bandwidth –Increase of the equivalent bandwidth –Or reduce the bandwidth occupied by a BSS for the same equivalent bandwidth Importance of the channel bonding –The implementation with two front-end segments enables easy channel bonding, even in contiguous mode Better use of the whole band –Assuming the knowledge of the 5GHz band occupancy, it offers a good flexibility in the use of the band: possible switch for the best channel allocation –The two front-end segments implementation enables the possibility to sound the band while maintaining the link

16. doc.:IEEE 802.11-10/0103r1 Submission Laurent Cariou January 19, 2010 References [1] Cariou, L. and Benko, J., Multichannel transmissions, IEEE 802.11-09/1022r0, Sep. 2010 Youhan Kim, AtherosSlide 16