The recently-released European Telecommunications Standards Institute’s (ETSI’s) report on Key Performance Indicators (KPIs) in the millimeter-wave and microwave backhaul promise to bring significant benefits to the Mobile Network Operators (MNOs) in managing the ever-growing need for more capacity as the number of subscribers with new services demanding high bandwidth continues to increase.
“A major benefit for the operator is the possibility of lowering the Total Cost of Ownership [TCO]. The 5G traffic is very mature, with many more users and new services, which requires a very massive increase in capacity. So let’s say tenfold or even more. Since there are limits to what we can do in improving spectrum efficiency, the lowest cost way to transmit more capacity is to use more spectrum so that means that we need to explore higher frequencies, which are more affected by rain attenuation and limited in terms of hop length. The use of new KPIs will permit operators to have a much lower total cost of ownership for the backhaul by avoiding over-engineering,” said Renato Lombardi, Vice President of Huawei’s Microwave Product Line, in an exclusive interview with Total Telecom.
Understanding new ETSI KPIs for Microwave Backhaul
He emphasized that the major philosophy behind the recently released ETSI’s KPIs for microwave backhaul is to not consider the microwave as a separated part of the network but to see it as a crucial part of an end-to-end network to provide a truly differentiated network experience to the end user.
There is a greater need to bring down the total cost of ownership because of over-engineering as the 4G and 5G traffic demand continues to rise. “Nowadays, with 4G and 5G traffic demand levels, the TCO impact due to link over-engineering is becoming bigger and bigger in terms of spectrum resources (license fees), size of antennas to be deployed, products to be used, etc. In other words, MNOs deserve a more suitable planning methodology in order to optimize MW/mmW backhaul links TCO,” says the ETSI report on New KPIs for Planning Microwave and millimetre Wave Backhaul Network.
The report further adds, “At the same time, this new planning methodology will ensure MNOs that MW/mmW backhaul links are properly serving RAN [Radio Access Network] traffic without impacting network performances, overall network KPIs and finally, the User Experience (most important aspect).”
Elaborating on the ETSI’s new KPIs, developed by Industry Specification Group (ISG), for the microwave industry, Renato Lombardi said, “The first point was to move from a concept of availability of capacity to the concept of availability of traffic. So the reason why we speak of availability for millimetre-wave link is that the propagation of radio waves at high frequencies is affected by rain, especially when we have stormy weather and heavy showers and we have to engineer the link in order to withstand fading coming from rain. Since microwave has a certain availability for different types of modulation, by moving from capacity to traffic, we wanted to link the probability of microwave being available together with the probability that the base station is requiring a certain capacity.”
The ETSI ISG has created a new metrics called Backhaul Traffic Availability (BTA), which represents the probability that the Microwave/millimeter wave backhaul link is capable of delivering the RAN traffic demand without any impact on the end-user experience.
“The second step in this direction in order to put together wireless backhaul and the wireless access to the radio access path was also to consider what level of reliability we need to provide, not just for the wireless backhaul segment itself, but for the end-to-end quality of experience for the end users. So we performed a lot of 5G RAN simulations, adding the models of the backhaul with an industry wide activity as several vendors and operators participated in this exercise,” says Renato Lombardi. The KPIs, which will impact the network planning and planning tools, involved two years of extensive work by several players of the major industry stakeholders.
“We have seen some simulations which we have full confidence that they will result in double the hop length, especially for the millimetre-wave resulting in an incredible cost advantage for the operators because the possibility to transmit multi gigabits over the E-band is definitely much lower cost, not only in terms of hardware but especially in terms of the cost of the spectrum.
Growing Importance of New Frequency Bands
It is important to explore new frequency bands since there is a need to increase the capacity in order to address the growing traffic because of 5G and 5G Advanced. “A few years back, we started working on the usage of the frequency bands above 90GHz, which we call W-band and D-band, which are two frequency bands that together can permit using more than 50GHz of spectrum. This will permit the allocation of huge capacity in one single channel, and this could also lead to potential applications not only for the backhaul but for the fronthaul itself,” says Renato Lombardi.
“So fronthaul is what is needed if the operators want to deploy a different type of architecture, what we call a centralized architecture. With the separation between baseband processing and the radio elements in a way that could lead to lower operational costs for the operators, especially in terms of power consumption, renting of sites and provision of mobile edge computing,” he added.
Even as new frequency bands are being explored, it is crucial to define licensing schemes and licensing fees to ensure that the telcos are able to deploy wireless backhaul and fronthaul cost-effectively. “For this reason, we propose a formula that takes into account the usability of the channels. We are about to publish a white paper on these concepts, especially on how to relate wireless backhaul costs to the penetration of 4G and 5G with benefits and their benefit on the country GDP. It is very important once again to underline the economical overall impact of 5G on the digital economy and how this is so tightly linked with the spectrum cost.”