Proposal to develop a draft new ITU-R WP 5D Report on IMT-2020 for remote sparsely populated areas providing high data rate coverage
ITU-R WP5D July 2019 meeting contribution by LM Ericsson
Ericsson proposes that ITU-R WP 5D develops a Report that addresses the specific needs for high data rate coverage for sparsely populated and under-served areas using suitable frequency spectrum bands.
[This author thoroughly agrees with Ericsson’s proposal!]
IMT-2020 networks have the capacity of satisfying the need for high data rate coverage for enhanced mobile broadband services in under-served and remote, sparsely populated areas. In this contribution we are suggesting that work be started on a Report giving details on prospects associated with the provisioning of enhanced mobile broadband services to remote, sparsely populated and underserved areas, proposing enhancements of user equipment (UE) as well as for networks in suitable frequency bands
- for user equipment, possible solutions based on affordable user deployed equipment combined with access to local spectrum at user premises could be considered and examined, and
- for network equipment, possible solutions based on high gain massive MIMO antennas could be reviewed.
A significant part of the global population is currently connected to existing cellular and mobile broadband sites. As a complement, users in remote sparsely populated and under-served areas could be connected to higher tower sites.
The proposed Report could, for example, consider an existing GSM cellular site grid designed for voice coverage, which could be estimated to reach high downlink data rates at a cell edge of IMT-2020 coverage ranges using conventional UE and network equipment. The Report would need, however, to focus on and consider the uplink performance characteristics which may be regarded as not being satisfactory without further elaborations on policy, spectrum and other aspects. For example, consider suggesting enhancements on UE and network equipment as well as consider using high tower installations that may provide coverage reach far beyond that is currently supported by typical GSM sites.
With regard to current perceptions, it is easy to get the impression that IMT-2020 is primarily targeting a shorter-range network build using millimeter wave (mmW) bands supporting extremely demanding requirements on latency, capacity, and very high peak data rates.
However, it is suggested that IMT-2020 is designed to operate in frequency bands ranging from low-bands to high-bands and can be configured to perform better or on-par with IMT-Advanced in every aspect, also in rural sparsely populated areas. IMT-2020 has evolved from IMT-Advanced, adding significant improvements to an already capable and proven design. IMT-2020 provides two fundamental benefits relevant for longer-range coverage
- Firstly, it is designed to fully utilize massive MIMO, and
- Secondly, it is based on a flexible and lean design reducing energy consumption.
To achieve longer-range, earlier cellular and mobile broadband systems have relied on low-bands. System operated in bands around the frequency range 450 MHz having excellent coverage, but with the limitation of available bandwidth. Pushing uses to higher and higher frequency bands is clearly resulting in increased capacity, but also in reduced coverage range.
For IMT-2020 massive MIMO configuration there is no longer a simple relation between low-band use and longer-range coverage. Using high-band frequencies the size of individual antenna element decreases, resulting in reduced efficiency of each antenna element. However, with massive MIMO this effect can be compensated for by adding antenna elements, effectively keeping the physical antenna size constant while moving to higher frequency bands.
Long-range cellular coverage is very much about using higher towers, higher power, and high gain antennas. In previous cellular systems, higher radio frequency (RF) power resulted in larger network energy consumption. IMT-2020 efficiently supports lean-design and massive MIMO as it provides the right tools to deploy longer-range systems supporting high peak data rates with lower average network energy consumption.
One offered solution to achieve both good coverage as well as high capacity is to use two or more frequency bands from low-band, mid-band and / or high-band, in an aggregated configuration. This approach has proven to be very effective in dense urban areas when deploying IMT-2020 in mmW bands in combination with a low-band or mid-band that can provide improved coverage.
When combined in an effective way, the high-band off-loads the traffic from the low-band and / or mid-band, resulting in significantly improved coverage as well as capacity. This could potentially also be a promising solution for bringing IMT-2020 to underserved rural sparsely populated areas. Combining IMT-2020 using a band in the range 3.5 GHz and IMT-Advanced in a band below the frequency 1 GHz on a GSM cellular grid can provide superior capacity compared to a standalone IMT-Advanced network deployment below 1 GHz. The reason being that in mid-bands in the range 3.5 GHz there is access to more bandwidth, and the low-band on a band below 1 GHz, provide coverage for cell edge users at the same time.
Considering the above, the proposed Report could review, discuss and assess the feasibility for potential enhancements for both network equipment and UE, it may consequently be viable to deploy IMT-2020 network in a band in the range 3.5 GHz providing high capacity and long-range coverage in underserved rural sparsely populated areas. This could be more feasible and economical than deploying new sites in these areas.
IMT-2020 could potentially provide high peak data rate and high capacity mobile broadband services in underserved rural sparsely populated areas by utilizing a band in the range 3.5 GHz, where typically 100 MHz bandwidth is available compared to 20 MHz that can be expected to be available in band in the range below 1 GHz. The Report could elaborate several possible enhancements using higher towers for extended range coverage. Further contribution based on studies, within the context of the proposed Report, would be required to find a technically as well as economically best practice solution resulting in sufficiently long-range, cell-edge throughput, and capacity. Such a solution could be to consider and review the use of both the existing grid of cellular towers and possibly the higher but also sparser television towers in combination, as well as reviewing a standalone 3.5 GHz configuration, or possible aggregation between the range 3.5 GHz for downlink and low-bands for uplink.
In addition, spectrum and policy aspects having a possible impact on a feasible network configuration may need to be addressed by a possible Report.
Ericsson proposes that WP 5D develops a draft new Report that addresses the specific needs for high data rate coverage for sparsely populated and under-served areas using suitable frequency spectrum.
Attachments 1 and 2 of Ericcson’s proposal, with more detailed proposals and time schedules, are only available to ITU member organizations and individuals with a TIES account.