1. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 1 Transmit Spectral Mask Changes Date: 2010-11-08 Authors:

2. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 2 Comment comment #10028 "TX mask limit should be softened. The strictness currently specified is not needed and imposes excessive constraints on designs. Existing 802.11a systems are built with a softer specification of -40 dBr and have not been shown to suffer from excessive interference issues in the field."

3. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 3 Comment comment #10028 "TX mask limit should be softened. The strictness currently specified is not needed and imposes excessive constraints on designs. Existing 802.11a systems are built with a softer specification of -40 dBr and have not been shown to suffer from excessive interference issues in the field."

4. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 4 Issues with comment 11n Transmit spectral mask was made after substantial discussion (one reason provided on slide 5) Relaxing the spectral mask leads to lower transmit power in the band edge channels. –FCC CFR47 part 15 Section.205: Restricted bands of operation, lists the channels part of the restricted band where OOB emission should not exceed -41.3dBm/MHz. Unequal transmit power capacity may lead to un equal sharing of unlicensed band

5. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 5 Comparison of Transmit spectral mask Proposed Change according to comment -40dBr 5dB

6. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 6 Effect of proposed spectral mask change on maximum Transmit Power 2390 2483.5 -40dBr fc = 2422 Channel 3 30 MHz -41.3 dBm/MHz -0.3 dBm/MHz “Regulatory + Mask change” Limits Band edge 20 MHz operation to < 13dBm Current transmit spectral mask allows 18dBm operation

7. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 7 Effect of proposed spectral mask change on Capacity 2390 -40dBr fc = 2422 Channel 1 30 MHz The relaxed spectral mask leads to 5dB loss in performance Loss in Capacity – 20MHz OBSS, 20 dB SINR using previous mask, 15dB SINR using new mask –C = BW x log2 ( 1 + SNR) –Loss in capacity = 32.6 Mbps OBSS 5 dB OOB Emission based on relaxed spectral mask 20 dB

8. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 8 Conclusion for comment 10028 The 11n transmit spectral mask was designed to allow operation at high transmit power and at the same time meeting the regulatory requirements. Technology has improved to allow lower power and cost PA designs which meets the current 11n Transmit spectral mask Relaxing transmit spectral mask requirement may lead to lower transmit power capability of future 11n devices operating at band edge channels Relaxing transmit power reduces performance of non adjacent channel BSS. No need to change the 11n transmit mask requirement

9. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 9 Comment comment #10088 "TX mask limits include an absolute value. This specification is not correct, and is also too stringent. It is not correct because the subbands of allowed operation in different regulatory domains have different absolute limits and this is not reflected by the single absolute limit that is provided. Secondly, the combination of an absolute and a relative limit is not correctly specified - the mask should be specified as requiring the device to meet the higher of the two values, relative and absolute. Same problems for 10 and 5 MHz masks."

10. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 10 What does 11n say 20.3.21.1 Transmit spectrum mask "When transmitting in a 20 MHz channel, the transmitted spectrum shall have a 0 dBr (dB relative to the maximum spectral density of the signal) bandwidth not exceeding 18 MHz, –20 dBr at 11 MHz frequency offset, –28 dBr at 20 MHz frequency offset and the maximum of –45 dBr and –53 dBm/MHz at 30 MHz frequency offset and above..“ “When transmitting in a 40 MHz channel, the transmitted spectrum shall have a 0 dBr bandwidth not exceeding 38 MHz, –20 dBr at 21 MHz frequency offset, –28 dBr at 40 MHz offset and the maximum of –45 dBr and –56 dBm/MHz at 60 MHz frequency offset and above”

11. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 11 How does 11n compute absolute OOB emission -45dBr 30 MHz -53 dBm/MHz 5 dBm = -8 dBm/MHz For 20 MHz, 30 MHz from fc –transmissions with transmit power greater than 5dBm shall have OOB emission 45dB lower relative to the transmit power –Transmissions with transmit power less than 5dBm shall have OOB emission not exceeding -53dBm/MHz For 40 MHz, 60 MHz from fc –transmissions with transmit power greater than 5dBm shall have OOB emission 45dB lower relative to the transmit power –Transmissions with transmit power lower than 5dBm shall have OOB emission not exceeding -56dBm/MHz 20 MHz -45dBr 60 MHz -56 dBm/MHz 5 dBm = -11 dBm/MHz 40 MHz

12. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 12 Conclusion for comment 10088 Relative power is clearly specified in IEEE 802.11n relative to the maximum spectral density of the signal. The absolute thresholds for both 20 and 40 MHz is specified correctly in the IEEE 802.11n specification. Any changes to the relative or absolute threshold may be considered to be –Out of PAR for Rev M –Considered by an expert group (PHY)

13. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 13 Questions ?

14. doc.: IEEE 802.11-11/0039r2 Submission Nov 2010 Raja Banerjea, Marvell SemiconductorSlide 14 Appendix – A (Restricted bands according to 15.205)