As we are moving further into the 5G era, the 5G mobile networks rollout is moving at full speed. To serve the ever-increasing 5G traffic, mobile operators continuously work at densifying networks in urban areas and expanding the 5G coverage in sub-urban and rural areas.
A critical factor for cost-effective acceleration of 5G networks rollout is the availability of economical 5G capable transport systems and in particular of wireless backhaul networks that connect the 5G base stations to the central sites. Fortunately, mobile operators can rely on novel Dual-Core Microwave (MW) backhaul solutions that facilitate a fast rollout, especially at tail sites, offer exceptional capacity and carrier-grade performance, while enabling CAPEX and OPEX optimization.
Wireless transmission systems have been an important part in the transport network technology mix and are expected to continue to be in the foreseeable future. Microwave (MW) transmission remain the preferred solution for mobile backhaul networks in areas that have a challenging landscape, where fiber cannot be optimally deployed. Of course, the availability is not the sole criterion, MW technical features and capabilities are also evolving in line with mobile networks requirements.
Modern MW Point to Point (PtP) IP solutions in licensed frequency bands 6-42 GHz (like Intracom Telecom’s OmniBAS™) have already become part of the 5G ecosystem by offering multi-Gigabit IP capacity. In parallel, advanced IP MW Long-Haul (LH) backhaul solutions at lower frequency bands (6-11 GHz), have enabled reliable wireless connection at longer ranges, usually 30 Km to 50 Km or more, and brought 5G to remote areas and islands.
Today 5G is continuing to grow at full speed. More than 250 operators have already launched commercial 5G networks worldwide serving more than a billion subscribers. It is seen that the 5G subscription uptake is faster than for 4G and is estimated that 5G users will reach 5 billion by 2028, resulting in explosive growth of 5G data traffic. Therefore, in the coming years the 5G networks deployment will continuously expand worldwide in order to extend coverage in broader areas and also densify networks in metropolitan cities.
MW backhaul networks will have an important role to help accelerating the diverse 5G rollout cases, which may be in different deployment phases for different markets and regions. Especially for 5G network expansions in under-served rural and sub-urban areas where the vast majority of the newly deployed 5G base stations will be tail sites, the MW technology is perfectly suited to provide the last-mile backhaul, from both technical and economical point of view. Noticeably, MW is the dominant backhaul technology in the last mile of 5G networks across rural and urban areas, at medium to long ranges, with more that 50% of all radio sites today connected via MW.
The desired technical capabilities of MW last-mile backhaul systems in growing 5G networks are analyzed in the following Section.
The essential requirements of modern MW radio systems for last mile 5G backhaul can be grouped in the following main categories:
The backhaul capacity needed for 5G varies depending mainly on the spectrum available by different operators and their regional network deployment phases. Estimations regarding required 5G backhaul capacity per site (up to 2025) converge to the following throughputs:
Therefore, the MW system must provide Gigabit capacity, easily scalable to Multi-Gigabit. To achieve Gigabit throughput, wide channels 112 MHz or more must be supported. To double this throughput a second channel need be used (If available). Doubling the capacity should not be realized by adding a second similar radio system in parallel, because this would double the cost of deployment. Ideally, the radio system must be ready to support two wide channels or a single wide channel in XPIC configuration in one unit, resulting in substantial CAPEX/OPEX reduction.
MW spectrum especially in urban areas, is scarce and saturated. A flexible utilization of scattered bunches of MW spectrum that may be available within the range of a frequency band, in different or same polarization, would help to exploit optimally the available spectrum and increase capacity.
To maximize the RF performance and enable long-standing and high throughputs, MW systems need employ advanced radio techniques. As an example, aggregation of two radio channels over one logical transmission stream is an essential functionality, which when combined with a robust Adaptive Coding and Modulation (ACM) algorithm would boost the radio performance and increase link availability at higher modulations.
New MW link deployments would be greatly simplified when using all-outdoor radios because there will be no need to reserve expensive space in a telecom room located in a private property. In addition, the number of units to be installed on the pole should be minimized. It is worthwhile mentioning that mobile operators have recognized the value of all-outdoor MW systems over the legacy split-mount ones and as consequence, their market share over split-mount systems is continuously increasing (Source: Independent Analysts & Intracom Telecom), as shown in Figure 1. Note that it is anticipated that the share of multicore modems and radios over the total radio shipments will continue to increase and reach 50% in 2025.
Reducing power consumption of new MW radios is a key requirement of mobile operators in their effort to lower operational costs and reach carbon footprint reduction goals.
MW backhaul solutions need be fully interoperable with 5G nodes and other transport systems to ensure a uniform handling of the various IP traffic flows across different 5G network segments.
New MW links would ideally be managed by an advanced OSS system and/or SDN Controller that provides service automations and prompt corrective and optimization actions, therefore reducing the operator OPEX.
All the essential requirements described in this section ultimately contribute to reducing the total costs for 5G operators, CAPEX and OPEX, which is fundamental for successful long-term business operation.
An ideal MW radio system for 5G last mile backhaul should have certain characteristics and technical capabilities that are outlined in this section.
First, it should be an all-outdoor compact unit. In an all-outdoor system, all the electronic circuits for the baseband and RF processing functions are enclosed in a weather proof outdoor unit. With zero footprint requirements, all the MW equipment is installed easily on the pole thus eliminating the need for expensive indoor space rental. Therefore, all-outdoor radios can accelerate the 5G rollout and facilitate both networks expansion and densification while optimizing the operator CAPEX and OPEX.
To enable higher throughputs required for last mile 5G backhaul, the MW all-outdoor unit should have a cutting-edge dual-core broadband architecture to support simultaneously 2 TX / RX RF signals of wide channels 112 MHz each. The CAPEX and OPEX optimization benefits of such a design are apparent. One unit instead of two needs be purchased, installed and maintained. It is anticipated that the cost of a dual-core unit would be significantly lower than the cost of two single-core units, resulting in clear CAPEX savings. Furthermore, a dual core radio will have simpler installation and require less cabling and other ancillary material.
The backhaul capacity supported by such a unit is 2.5 Gbit/s, which in most cases will be more than sufficient for last mile backhaul especially in rural and suburban areas. In areas where operators would need more capacity and the wireless hop length extends many km, MW dual core radio could be seamlessly combined with E-Band radios to support Dual-Band Links that can extend capacity and availability at longer ranges.
Efficient MW spectrum utilization by a dual-core radio is of paramount importance because spectrum is scarce and is usually available in fragments of various bandwidths in the same or different polarization. Therefore, the radio must be capable of allowing various carrier arrangements such as:
As depicted in Figure 2, a dual-core radio can exploit optimally the spectrum and support various link configurations by just fitting two types of compact integrated coupling units between the radio and the antenna. Such an integrated overall design would not only greatly simplify installation and slash operational costs but moreover offer better RF performance. In addition, it will be very valuable for operators if the dual-core radio could accommodate adaptable carrier allocations with replaceable RF band specific parts (duplexers).
Dual core MW radios at licensed frequency bands 13 GHz to 38 GHz are typically used in wireless links ranging from a few km up to 30 km or more. In all cases it is imperative that the MW system empowers Gigabit speeds with the best possible availability at higher modulations (4096-QAM). To achieve this goal, the dual-core radio must have a superior system gain and employ sophisticated signal processing algorithms, such as:
Thanks to their dual-core optimized architecture and the use of state-of-the-art components, modern MW radios consume less power than legacy MW systems, offering substantial OPEX savings to 5G operators. When a dual-core radio operates in one carrier, consumption can be reduced by 50%. Furthermore, the Automatic Transmit Power Control (ATPC) algorithm reduces TX power to the minimum needed to keep the link stable considering the varying propagation conditions, resulting in additional power savings up to 40%. As an additional improvement, traffic aware algorithms may deactivate the second carrier in the MW radio when 5G traffic is low, as an example during night hours, and ensure that the system absorbs just the right energy needed to serve the actual traffic.
MW backhaul systems already employ advanced L2 and L3 control mechanisms to handle effectively the IP traffic coming from the 5G base stations. Modern dual-core MW radios following the evolving IP/MPLS networking standards and adapting to new open architecture paradigms like SDN, with embedded NETCONF/YANG support, are future proof solutions with a long lifecycle, thus protecting the operator investments.
New dual-core MW links can be managed by powerful OSS systems that enable simple and efficient control of devices and services and offer sophisticated tools through the entire MW system lifecycle, from planning to commissioning, day-to day operation, auditing and long-term optimization. In addition, embedded SDN support would allow SDN Controllers (Intracom Telecom’s uni|MS™ Network Lifecycle Automation Platform and/or 3rd party) to directly manage services in an E2E fashion. Thanks to the smart automations supported, the network is always fine-tuned and the operators OPEX is minimized.
The technical attributes and capabilities of dual-core all-outdoor MW radios outlined in this section will decidedly contribute to minimizing the last mile backhaul CAPEX and OPEX, thus enabling operators to expand swiftly their 5G networks.
Novel dual-core MW radios address completely the communication service providers need for cost-effective, all-outdoor multi-Gigabit IP backhaul solution for 5G networks. Operators can achieve substantial CAPEX and OPEX savings thanks to system’s cost-effective architecture and exceptional performance, while accelerating the 5G networks deployment and expansion.
