5G Investment Accelerates but Telcos Cannot Ignore Their Antenna Upgrades

As we move firmly into the 5G era, the deployment and management of telcos’ antenna assets will become an essential element to building not only coverage but also capacity. The macro and roof-top cell sites are the mainstay of the mobile telco network, but the telco can experience constraints optimizing their deployments at the cell edge. The number of antenna mounts are limited at the top of the mast. Further, it is not just antennas being fixed to the mast. Engineers often need to install diplexers (which reduce the number of cables), tower-mounted amplifiers (which boost the transmission and reception of signals), remote radio heads (which reduce the coaxial feed line losses from long cable runs), and active antenna units (which can add potentially a 100 kilograms to the top of a tower). Six out of ten cell sites now belong to tower management companies that charge fees depending on antenna elevation, the length and weight of the antenna, and any antenna-associated equipment.

As a result, telcos need to consider consolidating stand-alone antennas to support various existing 2G (900 MHz), 3G (1.8 GHz), 4G (2.6 GHz), and 5G (3.5 GHz) frequency bands into (ideally) a single antenna unit. Further, these multiband antennas need to keep the main and side lobe coverage within predefined dimensions to reduce interference with other sectors or operators.

The original LTE deployments relied on two antennas on both the transmitter and the receiver (a 2×2 configuration). To deliver gigabit data rates, this has required the deployment of a 4×4 Multiple Input, Multiple Output (MIMO) antenna and 256 quadrature amplitude modulation in combination with carrier aggregation. In 2020, there has been an increasing number of LTE 8×8 MIMO antennas (3GPP Release 10) being deployed. In the 3GPP Release 11, the nature of antenna functions shifted from passive/fixed to active/adaptive. MIMO is capable of supporting adaption in the vertical plane to ensure better coverage in high-rise buildings (full-dimensional MIMO). In 3GPP Release 13, LTE Advanced Pro brought support up to 64 antennas as well as Multi-User (MU) MIMO. The addition of MU-MIMO allows the streams from an access point to be distributed to multiple devices at the same time. One consequence of increasingly complex MIMO will be the power draw needed to support transmissions. A 64T64R MIMO-integrated active antenna requires more than 800 watts.

Massive MIMO antennas, with their high gain capabilities, can help increase the link budget to end users who may be watching videos or playing games online; these antennas can also improve cell-edge performance. While high-order massive MIMO antennas (i.e., 64T64R or 32T32R) may be deployed in dense urban areas, lower-order massive MIMO antennas may be deployed in semi-urban and even rural areas as 8T8R or 16T16R configurations. These lower-order MIMO deployments can in fact maximize coverage for the minimum deployment of cell sites.

Vendors have been tackling these cell-site antenna challenges by developing a range of complementary antenna solutions. For the various Frequency Division Duplex (FDD) only, FDD/Time Division Duplex (TDD) combination, and multi-sector/MIMO antenna deployment scenarios, mobile operators need:

• a sub-3 GHz full-band 4T4R all-in-one antenna design in a side-by-side to minimize the antenna profile;
• a flexible antenna platform that can support either a full range of spectrum options in an FDD 4T4R or a TDD 8T8R antenna that can transmit/receive in the 2.3 GHz to 3.8 GHz range (dense urban scenarios require these to be under two meters);
• an ultra-wideband antenna that can operate between 1.8 GHz to 2.6 GHz and can support 1.8 GHz, 2.1 GHz, and 2.6 GHz 4T4R or an integrated low-band 2T4R with a high-band 4T4R three-sector for “all-in-one” configuration; and
• an active 5G active antenna unit and passive 2G/3G/4G antenna with a single antenna housing (markets such as Europe require the total height is constrained to two meters while supporting sub-6 GHz frequency bands—i.e., 2G, 3G, 4G and 5G).

Mobile telco radio-access-network departments are very much getting on with the business of upgrading their networks to support 5G. Through the successive generations (2G to 4G and now to 5G), the maturity cycle has been accelerating. 5G is likely to surpass 500 million subscriptions within three years; 4G took five years to reach this milestone. With operators needing to support not only the 900 MHz, 1.8 GHz, 2.3 GHz, and 3.5 GHz bands but also the 26/28 GHz and the 700 MHz bands, field engineers will need cost competitive, compact, and high-performance antenna solutions to meet the expectations of their customers—both consumers and enterprises.