The Evolution & Economics of E-Band for Wireless Backhaul
The E-Band frequency spectrum is enabling a host of speed, capacity, and cost efficiencies for metro wireless networks.
The ongoing, rapid proliferation of wireless devices and accelerating demand for bandwidth-intensive data services is putting a strain on point-to-point and backhaul radio networks, and cellular base stations, particularly in densely populated metro environments. To mitigate this strain, mobile operators are embracing the E-Band frequency spectrum (71-76 GHz and 81-86 GHz) as a means to expand wireless network capacity at fiber-caliber data rates.
To date, the 6-38 GHz frequency bands have been attractive options for aggregated cellular backhaul, but spectrum in a number of these bands is growing congested. Offering a maximum allocated channel bandwidth of 56 MHz, owing to the limited spectrum available at these lower frequencies, more radios are required in order to continue scaling capacity, and this naturally raises equipment and installation costs while further intensifying the congestion problem.
The E-Band frequency spectrum, on the other hand, isn’t nearly as crowded, and the ample 10 GHz of available spectrum has allowed regulators to allocate relatively wideband channels. This yields a considerable capacity-per-radio ratio advantage, and enables the ability to scale to data rates from 1 Gbps today, up to 10 Gbps in the future. At these capacities, E-Band wireless infrastructure shrinks the performance gap against traditional fiber at a fraction of the capital expense required for fiber deployment.
Further, the cost of licensing E-Band spectrum is low compared to lower frequency spectrum, mainly because the demand for E-Band spectrum is low. Narrow transmission beams ensure that interference risk within the E-Band spectrum is minimal, enabling regulators to implement a ‘light’ radio licensing scheme. Under this model, licenses can be secured quickly and at low cost.
Going the Distance
E-Band wireless infrastructure is also ideal for backhaul in small cell networks, because it can support link distances of approximately between one and three miles. This is a considerably longer transmission distance than what is possible at 60 GHz at comparable data rates, distinguishing E-Band as a compelling, cost-effective means of filling the gaps between the fiber backbone and densely populated areas not accessible by fiber.
The evolution of E-Band wireless infrastructure is closely linked to the attendant economics. Sales and deployments of E-Band transceivers have been relatively low to date, but E-Band-focused design activity is accelerating, and volume ordering is expected to rise between 3 and 5 times in 2014.
This shift to higher volume is enabling (and being enabled by) reductions in the cost of radio components. Where previously only a limited number of vendors serviced this market, the field of competition is expanding, putting downward pressure on component pricing. As a result, E-Band transceivers are expected to achieve price parity with lower band (38-42 GHz) transceivers in upcoming years.
Meanwhile, the pace of vendor innovation is accelerating, particularly within the power amplifier domain. Significant gains in PA output power and linearity are yielding the fiber-caliber transmission speeds that make E-Band wireless backhaul so compelling. MACOM has introduced additional cost efficiencies with the recent introduction of the high power (Psat 25.5 dBm) PA to span the full E-Band spectrum (71-76 GHz and 81-86 GHz) in a single product. This enables point-to-point transceiver designers to maximize design, space, and cost efficiencies by eliminating the need to integrate two discrete amplifiers to provide full E-Band support.
This also introduces manufacturing process and cost efficiencies via a reduction in component count, and while today’s E-Band PAs are offered as bare MMIC dies, further manufacturing efficiencies will be realized in the near future when these devices become available in surface mount packages. Standard SMT assembly will enable customers to accelerate time-to-market by leveraging commercial best practices for high-volume manufacturing, ensuring a host of additional benefits including improved assembly yield and reduced touch labor.
E for Exciting
There are other macro dynamics in play that might further impact the evolution, economics, and deployment of E-Band wireless infrastructure in the years ahead.
In developing countries, the low frequency links that underpin metro networks are heavily saturated. Mobile operators in these countries, often unencumbered by the constraints of legacy network architectures, may come to embrace E-Band infrastructure for wireless backhaul servicing aggregated backhaul and small cell backhaul in terrain that’s ill-suited for fiber trenching.
In regions of the world where wireless infrastructure is already pervasive, E-Band links could one day supplant existing lower frequency links as a means to support higher data rates over longer distances, while minimizing the number of network nodes required to ensure carrier-grade service availability in cities. This transition could impact millions of existing links.
In all of these scenarios, E-Band wireless infrastructure provides clear benefits for bolstering data services in metro environments, offering capacity headroom to spare today and into the immediate future. With E-Band spectrum at our disposal, we are now in the early adoption phase of a wireless technology evolution that will unfold over the next ten to fifteen years, causing seismic shifts across the wireless technology and market landscape.
This article originally appeared in the January/February print issue. Click here to read the full issue.