1. TGah STA Analysis for Smart Grid Use Case
Month Year
doc.: IEEE yy/xxxxr0
TGah STA Analysis for Smart Grid Use Case
Date: March 14, 2011
Authors:
Name
Company
Address
Phone
Stefan Aust
NEC Communication Systems, Ltd.
1753 Shimonumabe, Nakahara-ku, Kawasaki, Kanagawa , Japan
John Doe, Some Company

2. 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.

3. About IEEE ah
This amendment defines an OFDM PHY operating in the license-exempt bands below 1 GHz, e.g., MHz (Europe), MHz (Japan), MHz, MHz, MHz, and MHz (China), MHz (Korea) and MHz (USA) and enhancements to the IEEE MAC to support this PHY, and provides mechanisms that enable coexistence with other systems in the bands including IEEE and IEEE P g. [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 WLAN user experience for fixed, outdoor, point to mulit point applications.

4. Smart Grid – Number of IEEE 802.11ah STAs(*)
Number of IEEE ah 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: [3]
Discussion
Does the suggested number of 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

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

6. 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

7. Some base data Kawasaki, Japan Total number of households in Kawasaki
144,35km2 (area) [4]
(people), May 2008
9.465 people/km2
Total number of households in Kawasaki
(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

8. 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 nodes as number of associated STAs for TGah Smart Grid Use Case.
Add statement:
“The number of ah associated STAs may vary due to given outage probability and channel characteristic. The number may also vary due to applied meter strategies.”
Slide 8

9. References
[1] IEEE P Wireless LANs, Proposed IEEE ah Use Cases, IEEE /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 P Wireless LANs, Association ID management for TGah, IEEE /0088r0
[4] Kawasaki, Kanagawa, Wikipedia
[5] The population of households in Kawasaki