THE NEED FOR UBIQUITOUS CONNECTIVITY
As terrestrial networks evolve to 5G to meet the ever-increasing need for ubiquitous connectivity, many operators are realizing that mobile networks cannot by themselves achieve global coverage without assistance from satellite constellations. This is especially true at the network edge, over the oceans and in remote land areas. Such ubiquity is becoming essential in how industries compete and generate value, how people communicate and interact and how militaries pursue security for their citizens. As the number of subscribers, uses and requirements of connectivity continue to grow exponentially, so does the importance of extending terrestrial 5G networks beyond the urban and densely networked communities. We believe the result will be a unified network infrastructure that incorporates terrestrial 5G networks and large multi-orbit constellations to increase the scale and scope of access to communications networks.
In a 5G terrestrial network, satellites serve as an ideal means of providing additional backhaul, incorporating redundancy to critical segments and delivering greater connectivity to remote and rural areas. The 3GPP standards body considers non-terrestrial networks (NTNs), including high-altitude platform systems, drones and non-geostationary and geostationary equatorial orbit (GEO) satellites as an area of expansion for 5G. They feel this is important enough to include support for NTNs in Release 17.
THE CHALLENGE OF MERGING TECTONIC FORCES
In recent years, NTNs have matured rapidly with help from the advances of multiple industries including cost reduction of satellite launches, new and disruptive business models in low earth orbit (LEO) and GEO constellations, cost reductions of ground terminals and the global initiative to break down the “digital division” of connected and non-connected areas. Meanwhile, terrestrial networks across the globe are migrating from 4G to 5G. With the inclusion of NTN in 3GPP Release 17, the grand vision of merging terrestrial telecom networks and NTN is starting.
For this grand vision of convergence to become a reality, the industry needs to address the following:
- Satellites will need to play a far more central role within telecommunications networks going forward with both terrestrial and space-based components working in tandem for a wider diversity of functions at price points that are acceptable for mass market adoption
- Coordinating and selecting NTN spectrum managed and owned by different entities and managed by different countries
- Adding technology to today’s smartphones to communicate with LEO satellites located 500 km above the earth without increasing the cost of the handset.
- A new 3GPP standard revision is needed to tolerate various unique attributes of NTN networks including long signal delays to and from the satellite, the doppler shift due to the satellite’s speed and the large cell size (~30 km2 per cell area for LEO)
- Solving the NTN and terrestrial networks spectrum puzzle to effectively re-use spectrum already assigned to each segment to avoid interference between the space and the terrestrial segments
- A holistic network architecture to accommodate and connect different terrestrial service providers in different countries.
One common intersection of terrestrial networks and NTNs is that both require advanced phased array active antennas to drastically increase antenna gain in the gNB, handset, LEO satellite and satellite ground terminal radios. Low-cost, high performance active electronically scanned antennas (AESAs) will be the key enabler to the merging of terrestrial and NTNs.
SOLVING THE PRICE QUESTION FOR MASS MARKET ADOPTION
To reach attractive consumer price points, the industry must leverage the cost reductions learned from Wi-Fi technology introduced in the early 2000s and apply them to 5G and satcom networks. Silicon for mmWave ICs is the technology that achieves the delicate balance of cost and performance for commercial deployment of phased array antennas in 5G and satcom systems. Active antennas follow a typical volume curve of cost decreasing with increased volume, very similar to other consumer electronics, where the best value comes from a flexible solution that can meet the needs across all market segments.
Silicon ICs built on a commercial silicon process designed for volume RF device production is a key enabling technology. This technology helps to make electronic beam steering in flat panel active antennas commercially viable at both volume and cost points. Planar phased arrays utilizing a multi-layer commercial printed circuit board (PCB) construction with standard surface-mount assembly is the finishing technology needed to build commercially viable antennas in volumes that meet consumer price goals.
SOLVING THE TECHNICAL QUESTIONS
To create the phased array of the future that is cost-effective and enables convergence and coexistence, one must consider several factors:
The many satcom and 5G use cases lead to differing power, noise and cost requirements for the antenna. Active antennas are naturally a good technical solution as they are inherently scalable in size with the right design implementation. Anokiwave’s mmWave Silicon IC portfolio offers a complete RF signal chain solution for 5G mmWave arrays with system-level performance optimized for each 5G use case. This enables OEMs to rapidly design arrays to meet any given use case within a scalable platform. This platform offers proven capabilities in handling use cases with different EIRP requirements, from low to the maximum allowed under the FCC. Figure 1 demonstrates how an array based on the quad-channel beamforming architecture scales in EIRP and frequency to address multiple use cases in multi-region markets. For very large satcom terminals, scaling is achieved through scalable sub-array building blocks. This is based on the same concept as 5G arrays and it allows systems to be designed and easily sized based on the application requirements.
Silicon ICs used in phased array antenna designs offer high performance, application flexibility and ease of integration, high energy efficiency and compelling economics. For the highest performance in any radio system, the power amplifier and low noise amplifier need to be placed as close to the antenna as possible to minimize front-end feed loss. In phased array antennas this means that the Tx/Rx and beam steering functions need to be placed right at the radiating element. Since the distance between radiating elements in the array (the lattice) is typically one-half wavelength, this means the real estate available for the phased array antenna electronics is quite limited, especially at higher frequencies where the wavelengths are very short. Silicon beamformer ICs (BFICs) provide the optimum balance of integration of the RF, analog and digital functions all within a single IC. This results in an active antenna with significant cost savings and simpler planar construction. The underlying architecture for the BFICs in both 5G and satcom systems is the same, ensuring maximum economies of scale from each market.
Active antennas for both 5G and satcom must be designed to support a wide range of temperature environments, with satcom terminals having the most stringent requirements. Satcom airborne user terminals are a good example of the temperature extremes experienced by all terminal types in all markets. They must operate on the tarmac where temperatures can reach well over 120°C with solar loading and at -46°C to -62°C when the altitude of the aircraft is over 40,000 ft.
This temperature range requires good thermal designs with stable performance of the electronics over temperature. BFIC architectures can be a significant driver depending on the implementation. Phase shifter circuits implemented with vector modulators will require significant amplitude and phase calibration across temperature as their performance varies with temperature. Anokiwave avoids this challenge by using propriety structures that have stable amplitude and phase performance over temperature.
A misconception in the industry is that satcom terminal receive ICs require dual-beam implementations to support a make-before-break connection. Currently, none of the LEO providers support multi-beam handoffs. The make-before-break connections are managed in the network, enabled by the inherently fast beam steering capabilities of the active antenna.
For future satcom terminals to benefit from the volumes of the 5G market and for the convergence of the two networks to be commercially viable, the underlying architecture needs to remain constant. This is true, not only for the devices but also for the PCB design. Single-beam architectures come with significant savings that result from removing the requirement to integrate a second analog beamforming network or include more complicated and costly digital beamforming to achieve the dual-beam architecture. The result is savings in complexity, power and cost.
THE FUTURE OF CONNECTIVITY AND CONVERGENCE IS NOW
Market trends predict market convergence in the very near future. These are the trends that we are seeing:
Megatrend 1: Connecting the unconnected with the most economical solution that makes the business case for operators and consumers commercially viable.
Megatrend 2: Ubiquitous connectivity requires satellite systems to meet the full spectrum of demands placed on 5G networks. These include increasing the traffic and the number of connections outside city centers, providing coverage for devices on the move and seamlessly connecting the asset at the edge of the network as it moves away from an area of dense connectivity.
Megatrend 3: Increasing energy efficiency in future networks as operators look to reduce their carbon footprint while increasing the capacity of their networks. By using satellites to connect low density areas, operators can eliminate large numbers of tower-mounted base stations that consume power and only serve a few subscribers.
Megatrend 4: NTN systems offer benefits to public safety by providing overlay networks that duplicate critical segments of terrestrial networks. In the event of a catastrophe, an NTN can provide additional resiliency through redundancy.
Figure 2 shows a graphic of the future of connectivity and convergence. To realize these mega market trends, we believe that commercial, high volume terminals communicating with multi-orbit satcom and 5G systems require low-cost antennas with extremely fast steerable beams. We believe these systems must be designed with IC architectures that enable stable temperature performance and a flexible polarization scheme. The Anokiwave silicon-based mmWave BFICs improve performance, reduce cost, simplify thermal management and provide a host of unique digital functionality to simplify overall system design and enable the optimal AESA solution for the future of convergence and coexistence.
Anokiwave has been in these markets for over 20 years. The company has developed multiple generations of both satcom and 5G products shipping in volume production and offer OEMs unparalleled application expertise. This allows customers to develop better arrays with faster time to market as well as, most importantly, the experience to support customers who are expanding their networks beyond traditional 5G or satcom use cases.