Ofcom s CFI on spectrum above 6 GHz for future mobile communications (January 2015)

Transcription

1 Ofcom s CFI on spectrum above 6 GHz for future mobile communications (January 2015) Background Ofcom plans to use the responses from stakeholders to inform its contributions to European preparatory meetings for WRC-15 at which the scope of a future WRC-19 agenda item on bands above 6 GHz will be considered. The output will also help Ofcom to inform the positions it will take at WRC-15 itself and in other European or international discussions addressing future spectrum requirements for 5G. Deadline for responses is 27 February Ofcom expects to publish a summary of responses and an update in Q This document In this document is the answer of ETSI ISG mwt to Questions raised, with a specific consultation, by Ofcom, on spectrum above 6 GHz for several aspects related to future mobile applications. ISG mwt is a recently approved ETSI Group, including leading telecommunications network operators, equipment manufacturers, and component manufacturers working towards the common goal to facilitate the use of the V-band (57-66 GHz), the E-band (71-76 & GHz) and in the future higher frequency bands (from 50 GHz up to 300 GHz) for large volume applications in the backhauling and front-hauling to support mobile network implementation, wireless local loop and any other service benefitting from high speed wireless transmission - Extensive answer was given especially to question 6 that is related to backhaul. Questions not specifically addressed or potentially impacting backhaul have not been considered. Answers took account the need of bandwidth necessary for backhaul, the possibility of such high RF portions sizes being available in RF bands, the current use of traditional RF bands and of V- and E- bands. Considering that E-band is felt now as the only possibility for operators to transmit multiple Gbit/s over a few kilometers at a reasonable cost, regulatory framework related to potential allocations of bands currently used for backhaul (mainly e-band) to 5G, (expected to be deployed around 2020) should take account the need no to endanger the capability of operators to have wireless backhaul for 4G, not excluding the possibility to deploy small cell broadband access in the longer term. ETSI ISG mwt answers are marked in blue colour 1/7

2 Ofcom questions and ISG mwt responses Question 1: Are there practical ways of achieving the very high performance that use of wide channels above 6 GHz could offer, for example using carrier aggregation of lower frequency bands? Section 2. Technology developments and spectrum implications to achieve significantly increased data rates for mobile broadband, such as the preliminary figures currently being discussed (10 50 Gbit/s), much higher bandwidths are expected to be needed, for example, bandwidths of 1 GHz are being discussed within the ITU-R... Bands above 6 GHz, where there are larger contiguous frequency blocks and spectrum is less fragmented, present a more realistic opportunity to meet these requirements than bands below 6 GHz. 2.4 Multiple lower frequency, narrow bandwidth channels aggregated together could, in principle, be an alternative to using contiguous spectrum above 6 GHz. However, there are likely to be technical constraints, which in practice limit the number of channels that can be aggregated efficiently in a mobile device. ETSI mwt ISG has no specific comment to offer for Question 1 since it s focused on frequencies above 50 GHz for large volume Question 2: What recent or emerging advances in technology may provide effective solutions to the challenges in higher frequency bands? For example can increased propagation losses be mitigated by using the high gains available with massive MIMO? Ofcom key points ( ): Mobile broadband systems are more complex at higher frequencies, particularly in terms of the radio frequency (RF) front end, antenna design, and the need to combat higher propagation losses. The power output of amplifiers and oscillator stability are particularly challenging. Increased propagation losses at higher frequencies may mean that the range of a cell could be 200 meters or less mobile devices will need to operate over a wide range of frequency bands, i.e. both below and above 6 GHz advanced antenna techniques... may allow the exploitation of higher frequency bands so far unused by current mobile broadband technologies by overcoming some of the associated propagation constraints Greater use of small cells may also support the use of higher frequencies there continues to be research in the use of higher bands including developments in semiconductor and antenna technologies. ETSI mwt ISG has no specific comment to offer for Question 2 since it s focused on frequencies above 50 GHz for large volume Question 3: Are there any fundamental/inherent frequency constraints of the 5G technologies currently being investigated with regard to: ETSI mwt ISG has no specific comment to offer for Question 3 since it s focused on frequencies above 50 GHz for large volume a) minimum contiguous bandwidth per operator? Will the spectrum for multiple operators need to be contiguous (ie a single band) or could multiple operators be supported through multiple bands? 2/7

3 b) frequency range over which the technologies are expected to be able to operate, for example due to propagation, availability of electronic components, antenna designs and costs of deployment? For example, is GHz better or worse than GHz and why? Question 4: Will 5G systems in higher frequency bands be deployed, and hence need access to spectrum, on a nationwide basis or will they be limited to smaller coverage areas? And if so, what sort of geographic areas will be targeted? 2.11 In addition, above 6 GHz, sharing of the spectrum may become easier due to the limited range of the systems and this could be further improved by the use of advanced antenna techniques with greater directionality. ETSI mwt ISG has no specific comment to offer for Question 3 since it Question 5: a) To what extent will 5G systems in higher frequency bands need dedicated spectrum on a geographical and/or time basis or can they share? Due to its scope, ETSI mwt ISG only submits a response on backhaul aspects, why there are no comments on question 5. Regarding sharing of Mobile Services with Fixed Services see the answer on question 12. b) If they can share, what other types of services are they likely to be most compatible with? c) What technical characteristics and mitigation techniques of 5G technologies could facilitate sharing and compatibility with existing services? d) Could spectrum channels be technically shared between operators? Question 6: a) Given the capacity and latency targets currently being discussed for 5G how do you anticipate backhaul will be provided to radio base stations? Are flexible solutions available where the spectrum can be shared between mobile access and wireless backhaul? b) What, if any, spectrum will be required? What channel sizes will be needed? Will the bands used be similar to those currently used for wireless backhaul? Microwave and millimeter wave backhaul is a key element of current backhaul networks and is expected continue to evolve with LTE and as part of the future 5G ecosystem. The millimeter wave spectrum bands are already being used and are growing importance to support multigigabit transmission in urban areas. The latency of a backhaul radio link is lower than that of the fibre-optic cable due to faster propagation and direct propagation. Thus the lowerst latency links can be built with backhaul radio links. The expected data volumes on the access require also high-capacity backhaul links, and aggregation of large number of nodes over a single backhaul link may not be desireable. For coverage building, however, multiple backhaul radio link hops aggregating traffic from a large number of nodes is more feasible due to statistical multiplexing. For both very high area capacity based on small cells, as well as wide high data rates area coverage, it is required a cost effective high-capacity backhaul, for which radio link is in many cases the only viable option. Assuming e.g. that 10 Gbit/s will be required by each operator for backhaul and 4 operators/country can be foreseen, at least two paired 5 GHz bands will be required (1 spare channel for coordination / reuse), possibly contiguous. 3/7

4 Such amount of contiguous band can today be available only in frequency bands higher than traditional frequency bands used by FS, i.e. above 50 GHz. In order to understand the requirement for fixed services to cover the need to transport wider capacities, ( both in backhaul but also in other usage), the correlation between required bandwidth and the achievable data rate is to be considered. Current technology for FS (including backhauling) is mature to allow covering capacity of 10GBit/s in 2 GHz. E-band appears the one RF band capable of allowing transmission of such capacities over few kilometres at reasonable cost and should be the ideal solution for backhaul of first aggregation signals (backhauling of macrocells / suburban areas ecc). Concerning backhaul for small cells (eg street level in urban areas,) ISG opinion is that V band, allowing practical BW of few hundred MHz, is expected to play a key role in next and mid-term future. An option discussed for 5G is to use the same radio access technology for both access and backhaul with dynamic sharing of the spectrum resources, a.k.a. self -backhauling. This might provide a complement to microwave backhaul in some specific ultra-dense deployments (indoor and also outdoor) by providing backhaul connectivity to/ between small cells. The ETSI mwt ISG is of the opinion that these flexible solutions are likely to present a challenge that may need particular attention, if considered for sharing spectrum between applications with very different behaviors, as (dynamic) mobile services and (static) fixed services can be. There is a need for long-term strategic planning also regarding fixed service spectrum. It is important to consider the future spectrum needs for all parts of a country, from remote rural to dense urban areas. Consideration has to take into account that 5G will have different backhaul performance needs in different areas, just as is the case in today s mobile backhaul networks. The ETSI mwt ISG is of the opinion that not only it is important to preserve sufficient already allocated spectrum for fixed services and is planning to work on bands around and above 100 GHz for additional future wide bandwidth spectrum for backhaul. Therefore, initiating the process for identifying the suitable bands would be beneficial. A CEPT Questionnaire to upgrade ECC Rep. 173 with new info related to millimetre waves use in next few years includes RF bands up to 175 GHz; moreover, preliminary lab tests are ongoing up to about 140 GHz, as far as is known to ETSI ISG mwt. ISG mwt suggests to extend the range of analyzes up to 175 GHz, when considering backaul allocations. Question 7: Should we expand the scope of bands being reviewed beyond the GHz range? Section 3. Overview of bands above 6 GHz ETSI mwt ISG has no specific comment to offer for Question 7 since it Regarding backhaul spectrum see the answer to question 6. 4/7

5 Question 8: Do you agree that it is likely to be necessary for bands to have an existing allocation to the mobile service? Does this need to be a primary allocation? Footnote 16: The Radio Regulations state whether services have a primary or secondary allocation. Stations of a secondary service shall not cause harmful interference to stations of primary services, and cannot claim protection from harmful interference from stations of a primary service. For the purposes of this document, we use global primary allocation to signify where there is a primary allocation to the mobile service in all three Regions. ETSI mwt ISG has no specific comment to offer for Question 8since it Question 9: Do you agree with the criteria we have used for our initial filter of bands, and are there other criteria that could also be used? 3.4 Two factors that we think are likely to be relevant are international harmonisation and availability of sufficient bandwidth. We have conducted some initial filtering of the spectrum between 6 and 100 GHz in order to highlight spectrum ranges that meet the following criteria: an existing global primary allocation to the mobile service in the Radio Regulations; and contiguous bandwidth of at least 1 GHz. ETSI mwt ISG has no specific comment to offer for Question 9 since it Question 10: Of the spectrum bands/ranges mentioned in this section, are there any that should be prioritised for further investigation? MHz GHz (excl GHz) GHz GHz GHz GHz GHz GHz (excl GHz) GHz GHz GHz Question 11: Are there any bands/ranges not mentioned in this section that should be prioritised for further investigation? If so, please provide details, including why they are of particular interest. Questions 12: Are there any particular bands/ranges that would ETSI mwt ISG has no specific comment to offer for Question 7 since it. The ETSI mwt ISG notes that the only Fixed Service bands that is not mentioned as a candidate for 5G access is the 32 GHz band ( GHz) which is little used today. The ETSI mwt ISG only submit a response on backhaul aspects. 5/7

6 not be suitable for use by future mobile services? If so, please provide details. Question 13: What additional information, beyond that given in Annex 5 would be useful to allow stakeholders to develop their own thinking around spectrum options?. The feasibility of spectrum sharing between different services is a topic of study within the 5G research community, and evaluation on a bandper-band basis is needed. Specific sharing criteria need to be defined when introducing access services in the existing fixed service bands, allowing protection of existing services (fixed) from harmful interference. The ETSI mwt ISG is of the opinion that Fixed Service bands that are expected to be heavily used in certain areas or regions are less likely to be suitable for 5G mobile deployment in such locations, in particular for urban scenarios. Regional and ideally globally harmonization of spectrum use is beneficial. It is therefore important to also consider the regional as well as global planned future use of Fixed Service bands. Note that there are today large regional differences where, for example, North East Asia and North America use much less Fixed Services than the rest of the world. There are also large variations of which Fixed Service bands that are most heavily used. The ETSI mwt ISG only submits a response on backhaul aspects. For more information on current deployment situation and future trends for Fixed Services, specific info related to effective use of RF bands are useful. For CEPT info, EFIS electronic database, in addition with ECC Report 173 (Fixed Service in Europe, Current use and future trends post 2011) provide detailed information As a general indication, some frequencies below about 26 GHz and about 38 GHz are densely used, often as backhaul for current mobile, constituting a high percentage of microwave equipment put in the market The millimeter wave Fixed Service bands (70/80 GHz and also the 60 GHz band) are of rapidly growing importance to support multi-gigabit transmission in urban areas. Question 14: What are the most important criteria for prioritising bands going forward? ETSI mwt ISG has no specific comment to offer for Question 14 since it. 6/7