TGah STA Analysis for Smart Grid Use Case Month Year doc.: IEEE 802.11-yy/xxxxr0 TGah STA Analysis for Smart Grid Use Case Date: March 14, 2011 Authors: Name Company Address Phone email Stefan Aust NEC Communication Systems, Ltd. 1753 Shimonumabe, Nakahara-ku, Kawasaki, Kanagawa 211-8666, Japan +81 44 435 1177 aust.st@ncos.nec.co.jp John Doe, Some Company

Objective This contribution analyses the suggested number of associated STAs for a particular TGah use case “Smart Grid” [1]. Proposal to include a high STA density for TGah “Smart Grid” use case.

About IEEE 802.11ah This amendment defines an OFDM PHY operating in the license-exempt bands below 1 GHz, e.g., 868-868.6 MHz (Europe), 950-958 MHz (Japan), 314-316 MHz, 430-434 MHz, 470-510 MHz, and 779-787 MHz (China), 917-923.5 MHz (Korea) and 902-928 MHz (USA) and enhancements to the IEEE 802.11 MAC to support this PHY, and provides mechanisms that enable coexistence with other systems in the bands including IEEE 802.15.4 and IEEE P802.15.4g. [1] The data rates defined in this amendment optimize the rate vs. range performance of the specific channelization in a given band. This amendment also adds support for: transmission range up to 1 km data rates >100 kbit/s while maintaining the 802.11 WLAN user experience for fixed, outdoor, point to mulit point applications.

Smart Grid – Number of IEEE 802.11ah STAs(*) Number of IEEE 802.11ah STAs (point-to-multipoint) [1] Coverage area and outage probability (range), NIST PAP2 [2] Suggested density of associated STAs: 6.800/km2 [3] Suggested number of associated STAs within coverage area: 21.384 [3] Discussion Does the suggested number of 21.384 associated STAs reflect any suggestions/requirements issued by some states/countries regarding metering interval? Meter interval may be state/country specific (15min./30min./1h, etc.) Channel characteristic in high dense areas (6.000 nodes/km2) and low transmit power (e.g., 10mW) may not allow a high number of STAs to be covered. Should be discussed in the TGah channel model ad-hoc group. (*) Single STA in the (following) equals a single (outdoor) meter gateway per household Slide 4

Density, coverage radius, coverage area km Density (number of associated STAs/km2) e.g., 2.000 (urban) [2] 1 11ah STA 11ah AP 1 km Coverage area Coverage radius (TGah, up to 1km, outdoor, channel model undefined) Slide 5

Analysis associated STAs Frequency Environment Density Coverage radius Number of STAs 2.4 GHz Urban 2000 113m (0.1% outage) [2] 80 [2] 900 MHz 6800 [3] 2 times 2.4 GHz (*), higher density than [2] 1091 <900 MHz 3 times 2.4 GHz (*), higher density [2] 2455 Note that the largest coverage area achievable by a specific technology typicaly requires transmission at the lowest data rate used by that technology.[2] (*) under discussion in the TGah channel model ad-hoc group Slide 6

Some base data Kawasaki, Japan Total number of households in Kawasaki 144,35km2 (area) [4] 1.385.003 (people), May 2008 9.465 people/km2 Total number of households in Kawasaki 661.949 (March 1, 2011) [5] Density (households*) 4.586/km2 Similar range of density when compared with 6.800/km2 [5] *density of households equals the density of meter gateways Slide 7

Proposal Summary Number of associated STAs as proposed in [2] reflects a realistic density High density of associated STas can be confirmed, e.g., Kawasaki prefecture However, reduced coverage range due to outage probability may reduce the number of associated STAs within the coverage area. Proposal Include 21.000 nodes as number of associated STAs for TGah Smart Grid Use Case. Add statement: “The number of 802.11ah associated STAs may vary due to given outage probability and channel characteristic. The number may also vary due to applied meter strategies.” Slide 8

References [1] IEEE P802.11 Wireless LANs, Proposed IEEE 802.11ah Use Cases, IEEE 802.11-11/0017r5 [2] NIST Priority Action Plan2, Guidelines for Assessing Wireless Standards for Smart Grid Applications, revision 1.0, 12/31/10, National Institute of Standards and Technology [3] IEEE P802.11 Wireless LANs, Association ID management for TGah, IEEE 802.11-11/0088r0 [4] Kawasaki, Kanagawa, Wikipedia [5] The population of households in Kawasaki