Considerations on HEW Evaluation Methodology May 2013 doc.: IEEE 802.11-12/xxxxr0 July 2013 Considerations on HEW Evaluation Methodology Date: 2013-07-17 Authors: Name Affiliations Address Phone email Minho Cheong ETRI 161 Gajeong-dong, Yuseong-Gu, Daejoen, Korea +82 42 860 5635 minho@etri.re.kr Hyoung Jin Kwon +82 42 860 1698 kwonjin@etri.re.kr Jae Seung Lee +82 42 860 1326 jasonlee@etri.re.kr Sok-Kyu Lee +82 42 860 5919 sk-lee@etri.re.kr Minho Cheong (ETRI) Osama Aboul-Magd (Huawei Technologies)

Month Year doc.: IEEE 802.11-yy/xxxxr0 May 2013 Abstract This document tries to list up additional considerations on design of HEW evaluation methodology. Minho Cheong (ETRI) John Doe, Some Company

July 2013 PHY Impairments PHY impairments defined in 802.11ac Evaluation Methodology PA nonlinearity Carrier frequency offset For single user communications For Downlink MU-MIMO transmission For Uplink MU-MIMO transmission Phase noise Noise figure Antenna configuration (mix of vertically or horizontally polarized) Fluorescent light effect Timing offset for Uplink MU-MIMO transmission, [-100 100]ns with respect to reference Power difference needs to be considered due to non-ideal ranging For UL MU-MIMO transmission, [-TBD TBD] dB with respect to avg. power Minho Cheong (ETRI)

Network-Level Impairments July 2013 Network-Level Impairments In terms of topology and deployment of multiple BSS’s It may be desirable to newly introduce network-level impairments as well in addition to PHY impairments, which have a significant influence on the network performance Different from evaluation methodology till 802.11ac, HEW really wants to consider network-level evaluation taking multiple neighboring BSS’s scenario into account Such as Non-ideal deployment of AP and STA Hidden AP’s each other Non-ideal network sync. among multiple neighboring AP’s Minho Cheong (ETRI)

Network-Level Impairments (2) July 2013 Network-Level Impairments (2) How much is location of AP’s distorted from a originally expected location based on a fixed organized pattern design? One of key characteristics of Wi-Fi network is that it does not have a fixed pattern topology (such as hexagonal deployment) in real world, which is very specific feature of Wi-Fi compared to cellular network Location of STAs It seems OK to set in a purely random modeling over a area Location of AP Deviation from an expected location seems quite a more adequate design rather than just purely random positioning over an area, because every AP is likely to be deployed having some distance with others though it is not a well-organized design Example 3-D random deviation within [-V, V] + (X, Y, Z), where (X, Y, Z) is an originally expected location of AP based on design of hexagonal fixed pattern topology Minho Cheong (ETRI)

Network-Level Impairments (3) July 2013 Network-Level Impairments (3) How much portion of private AP’s or old-fashioned STA’s are existing in the simulation scenario? Private AP’s or old-fashioned STA’s are one of key reasons for big degradation on network performance We need to take into account several generations of Wi-Fi devices coexisting when try statistical modeling of multiple AP’s and STA’s in the simulation scenario Example X % of AP’s are private AP’s, which cannot be coordinated with other neighboring AP’s Y % of STA’s are old-fashioned STA’s [Y1 Y2 Y3 Y4] % for 11b/11g/11n/HEW STA’s in 2.4GHz Minho Cheong (ETRI)

Network-Level Impairments (4) July 2013 Network-Level Impairments (4) Timing offset among neighboring AP’s due to non-ideal network synchronization Irrespective of what level of AP-to-AP coordination we will really introduce, it may not be a bad idea to introduce non-ideal timing alignment offset among neighboring AP’s which may have a big impact on the performance of some coordination schemes Example When network synchronization is not applied Do not consider a specific range for timing offsets When network synchronization is applied Timing offset per each AP lies within [-t t] (ns) with respect to reference Minho Cheong (ETRI)

Simulation Scenarios Frequency allocation of neighboring BSS’s July 2013 Simulation Scenarios Frequency allocation of neighboring BSS’s We need to consider cases in which neighboring BSS’s have different frequency channels Also need to consider cases in which primary channels are not aligned with each other among neighboring BSS’s while supporting the same frequency resources in total In addition, we need to consider cases in which frequency channels of neighboring BSS’s are partially overlapped It is already introduced one in 802.11ac evaluation methodology reflecting the real world problem very common even now Minho Cheong (ETRI)

Simulation Scenarios (2) July 2013 Simulation Scenarios (2) Hidden AP’s each other while some of belonging STAs collide In most of HEW usage models, many BSS’s are likely to be much populated within a limited area So, there may be so many cases in which neighboring AP’s are hidden each other while those belonging STAs collide. So, we also need to take into account in the simulation scenarios. Minho Cheong (ETRI)

Channel Model Blockage effect in a dense scenario July 2013 Channel Model Blockage effect in a dense scenario In addition to general indoor (from 802.11n/ac channel model) or outdoor (from WINNER or ITU channel model), we need to consider the following environments as well Head-to-hand blockage effect Whenever a person watches his smart-phone, his own head is likely to block the link to AP many times, which has been a problem even in nowadays Other human body blockage effect In most of HEW usage models, many people are very crowded within a limited area with super high density more than 0.5 person/m2 or 1.0 person/m2. In these environments, we can hardly expect an LOS link between AP and STA due to blockage effect from other human bodies, which seems to require new channel modeling to solve this HEW-dedicated problem. Minho Cheong (ETRI)

July 2013 Channel Model (2) Different antenna direction depending on usage models In usual Wi-Fi hot-spot use scenario, physical direction of antennas equipped in the laptops or smart-phones may be purely random But, in some important scenarios of HEW usage models, such as super-dense urban usage model or exhibition hall in which most of people are very actively generating UGC and uploading/downloading Most of hand-held devices involved are likely to have a specific physical direction to the event in common. So, we also need to consider this characteristics of antenna direction effect depending on each specific usage model Because this also have a significant impact on network performance Minho Cheong (ETRI)

References [1] 11-09-0161-02-00ac-802-11ac-usage-model-document March 2012 doc.: IEEE 802.11-12/0330r0 July 2013 References [1] 11-09-0161-02-00ac-802-11ac-usage-model-document [2] 11-09-0451-16-00ac-tgac-functional-requirements-and-evaluation-methodology [3] 11-13-0554-00-0hew-Usage-models-for-HEW [4] 11-13-0657-03-0hew-hew-sg-usage-models-and-requirements-liaison-with-wfa [5] 11-13-0514-00-0hew-usage-scenarios-and-applications [6] 11-03-0802-23-000n-usage-models [7] 11-13-0840-01-0hew-HEW-functional-requirements-follow-up Minho Cheong (ETRI) Wookbong Lee, LG Electronics