doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Draft ETSI ERM TG28 Liaison response on EN ] Date Submitted: [4 th March, 2010] Source: [Larry Taylor] Company [DTC (UK)] Address [UK] Voice:[], FAX: [], Re: [Response to IEEE Liaison letter to ETSI ERM] Abstract:[Draft ETSI Response & Notes] Purpose:[Provide answers to questions on the interpretation of EN ] 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

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 2 ETSI ERM TG28 Liaison Draft Response to IEEE Liaison letter to ETSI ERM on EN

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 3 IEEE Questions requested ERM to clarify –Whether Wideband transmissions using Forward Error Correction coding should or should not be considered as DSSS transmissions for the purpose of interpreting EN rules? –How FHSS is differentiated from Adaptive Frequency Agility In particular, should systems which transmit one or more entire bursts (preamble and all frame data) on a single channel within the dwell time limit of 400ms before changing operating frequency be considered FHSS or not? –Whether there is an additional duty cycle restriction over Rec and if so why it was introduced? In EN V2.3.1, section , appears to include a restriction that does not seem to be aligned with the current version of ERC Recommendation published on the ECO web site This restriction appears to place an additional duty cycle restriction of approximately 3% per 200 kHz on devices that implement both LBT and AFA

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 4 ETSI ERM TG28 Draft Liaison Reply V2.3.1 of this standard has been developed after much work on the subject of co-existence between multiple users and different types of equipment, particularly in the MHz band. In particular, studies within both CEPT and ETSI have shown that high duty cycle transmissions (for instance under LBT+AFA rules) can cause harmful interference to other users (for instance those operating under duty cycle rules). Accordingly, it has been necessary to introduce sharing procedures, such as those in clause The parameters have been chosen so that they will achieve the required purpose with the minimum inconvenience. To address your specific points: The use of Forward Error Correction in itself would not affect the classification of a transmission. Whether it were to be considered “wideband” or “spread spectrum” would depend on the nature of the signal. ETSI ERM TG28 is aware of potential difficulties in discriminating between FHSS, Frequency Agile and Adaptive Frequency Agile transmissions. The wording of the FHSS and other sections in EN V2.3.1 has been updated to bring their treatments into line. You raise the example of a system that completes a message within the 400 ms dwell time limit. Whether this were FHSS or not would depend on the time pattern and frequency pattern of the following transmissions. In some ways, it is unproductive to ask the question; the intention of V2.3.1 is that the parameters the transmission must meet would be similar for either interpretation. The general limits applying across 863 to 870 MHz are 25 mW and 0.1% duty cycle for both FHSS and non-FHSS. It is believed that in this case there is no advantage to be gained by declaring such a device to be FHSS rather than Adaptive Frequency Agile or frequency agile. Great care has been taken in CEPT and ETSI to align the harmonised standards and Recommendation There is now a January 2010 version of Rec that has just been published on the ERC website ( Annex 1 of this is closely aligned with the latest EN and refers to it for definitions, etc. Rec is a recommendation to the administrations of CEPT member states; it should not in itself be taken as a specification aimed at product developers. Please note that while clause may be seen as a duty cycle restriction, the limitations only apply per channel. High duty cycles are still possible, provided the frequency is adaptively changed. ETSI ERM TG28 has a current work item in which it is continuing to study these matters of co-existence and spectrum sharing. Any contributions you wish to make would be welcomed. One of the topics to be considered is whether FHSS devices need a separate section in future versions of the standard or whether they can be treated under the general heading of frequency agile devices.

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 5 ETSI ERM TG28 Draft Responses Q - Whether Wideband transmissions using Forward Error Correction coding should or should not be considered as DSSS transmissions for the purpose of interpreting EN rules? A - The use of Forward Error Correction in itself would not affect the classification of a transmission. Whether it were to be considered “wideband” or “spread spectrum” would depend on the nature of the signal

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 6 FHSS vs AFA Q - How FHSS is differentiated from Adaptive Frequency Agility –In particular, should systems which transmit one or more entire bursts (preamble and all frame data) on a single channel within the dwell time limit of 400ms before changing operating frequency be considered FHSS or not? A - ETSI ERM TG28 is aware of potential difficulties in discriminating between FHSS, Frequency Agile and Adaptive Frequency Agile transmissions. The wording of the FHSS and other sections in EN V2.3.1 has been updated to bring their treatments into line. –You raise the example of a system that completes a message within the 400 ms dwell time limit. Whether this were FHSS or not would depend on the time pattern and frequency pattern of the following transmissions. In some ways, it is unproductive to ask the question; the intention of V2.3.1 is that the parameters the transmission must meet would be similar for either interpretation. The general limits applying across 863 to 870 MHz are 25 mW and 0.1% duty cycle for both FHSS and non-FHSS. It is believed that in this case there is no advantage to be gained by declaring such a device to be FHSS rather than Adaptive Frequency Agile or frequency agile.

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 7 REC Q - Whether there is an additional duty cycle restriction over Rec and if so why it was introduced? –In EN V2.3.1, section , appears to include a restriction that does not seem to be aligned with the current version of ERC Recommendation published on the ECO web site –This restriction appears to place an additional duty cycle restriction of approximately 3% per 200 kHz on devices that implement both LBT and AFA A - Great care has been taken in CEPT and ETSI to align the harmonised standards and Recommendation There is now a January 2010 version of Rec that has just been published on the ERC website ( Annex 1 of this is closely aligned with the latest EN and refers to it for definitions, etc. Rec is a recommendation to the administrations of CEPT member states; it should not in itself be taken as a specification aimed at product developers. –Please note that while clause may be seen as a duty cycle restriction, the limitations only apply per channel. High duty cycles are still possible, provided the frequency is adaptively changed.

doc.: g Draft ETSI ERM TG28 Liaison response on EN March 2010 Larry Taylor, DTCSlide 8 Questions