TGah STA Analysis for Smart Grid Use Case Date: March 14, 2011 Authors:
Objective • This contribution analyses the suggested number of associated STAs for a particular TGah use case “Smart Grid” . • 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.  • 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(*) • Smart Grid • Number of IEEE 802.11ah STAs (point-to-multipoint)  • Coverage area and outage probability (range), NIST PAP2  • Suggested density of associated STAs: 6.800/km2  • Suggested number of associated STAs within coverage area: 21.384  • 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)  1 11ah STA 11ah AP km 1 Coverage area Coverage radius (TGah, up to 1km, outdoor, channel model undefined) Slide 5
Analysis associated STAs Note that the largest coverage area achievable by a specific technology typicaly requires transmission at the lowest data rate used by that technology. (*) under discussion in the TGah channel model ad-hoc group Slide 6
Some base data • Kawasaki, Japan • 144,35km2 (area)  • 1.385.003 (people), May 2008 • 9.465 people/km2 • Total number of households in Kawasaki • 661.949 (March 1, 2011)  • Density (households*) • 4.586/km2 • Similar range of density when compared with 6.800/km2  *density of households equals the density of meter gateways Slide 7
Proposal Summary • Number of associated STAs as proposed in  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  IEEE P802.11 Wireless LANs, ProposedIEEE 802.11ah Use Cases, IEEE 802.11-11/0017r5  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  IEEE P802.11 Wireless LANs, Association ID management for TGah, IEEE 802.11-11/0088r0  Kawasaki, Kanagawa, Wikipedia  The population of households in Kawasaki