1. July 2010
doc.: IEEE xxxx
July 2010
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Proposal for TG6 Clause 9 Comment (ACPR S9-43, S9-41) Resolution -
Date Submitted: 14 July, 2010
Source: Peter Bradley, Zarlink Semiconductor
Re: Response to IEEE Letter Ballot comments
Abstract: This document proposes resolutions for Letter Ballot 55, for the Narrowband PHY section (comments related to increased hub ACPR S9-43, S9-41).
Purpose: For discussion by IEEE TG6
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
Peter Bradley, Zarlink Semiconductor
Anuj Batra and Mark Dawkins, TI and Toumaz

2. ACPR (Comment-Resolution)
July 2010
doc.: IEEE xxxx
July 2010
ACPR (Comment-Resolution)
Comment(s): S9-43, S9-41
“The ACPR levels for MICS band operation are not adequate to prevent hubs from interfering with implants (nodes) communicating in an adjacent channel.”
Proposed Resolution:
Add second column in table 48 such that we have two columns “ACPR (Node)” and “ACPR (Hub)”. Column ACPR(Node) will correspond to the existing column and values. Column ACPR (Hub) will be identical to ACPR (Node) with all values being -26 dB except for the MICS band where the value -35 dB applies to ACPR (Hub)
Peter Bradley, Zarlink Semiconductor
Anuj Batra and Mark Dawkins, TI and Toumaz

3. ACPR (Discussion) Discussion:
July 2010
ACPR (Discussion)
Discussion:
The ACPR specified for the MICS band is not low enough to prevent excessive interference from hub devices. There is a very large difference in signal strengths in air between nodes (-38 dBm, based on data from FCC filings (160 nW for FCC ID RAISJMRF, 200 nW for FCC ID LF5MICSIMPLANT2) and a maximum of -40 dBm for low duty cycle mode) and hubs (-16 dBm, base on regulatory limits) in typical MICS applications. This creates two effects (i) ACPR in nodes is not as critical as hubs (ii) the worst case interference scenario is a neighboring hub interfering with the weak node to hub transmission. Ideally, the desired ACPR for a hub is -48 dB whilst for a node under equivalent assumptions it is -26 dB. As a balance between ideal requirements and reasonable practical values a value of -35 dB for hub ACPR is recommended.
Peter Bradley, Zarlink Semiconductor

4. ACPR (Discussion) Red is interferer, green is wanted
July 2010
ACPR (Discussion)
The worst case interference scenario is a neighboring hub interfering with the weak node to hub transmission (Case 4)
Red is interferer, green is wanted
Peter Bradley, Zarlink Semiconductor

5. July 2010
ACPR calculation
ACPR = -(Phub-Pnode+SNR+margin) = -(-16-(-38)+SNR+9) = -48 dB (D8PSK) eg for D8PSK SNR=17 dB = -36 dB (DBPSK) eg for DBPSK SNR=5 dB
Assumes 9dB margin corresponding to 0.5 dB degradation in sensitivity
Use ACPR = -35 dB as a balance between ideal requirements and reasonable practical values
Peter Bradley, Zarlink Semiconductor