While the NEX10 and 2.2-5 connectors are available in a single port, the better use of the connector is as a multiport cluster. The Next Generation Mobile Networks (NGMN) Alliance recently recommended the Huawei Technologies MQ4/MQ5 cluster connector to support TDD 8T8R 5G RRU and antenna configurations. This was one of four connector systems submitted to the NGMN Alliance:
- 2.2-5
- MLOC (CommScope)
- MQ4/MQ5
- NEX10
Following aggressive lobbying efforts by Huawei, the MQ4/MQ5 solution was chosen (see Figure 4). The Rosenberger NEX10-4 cluster connector is shown in Figure 5, and CommScope’s MLOC-4 cluster connector, designed to be compatible with the NEX10, is shown in Figure 6. Unlike the others, the CommScope MLOC cluster solution is agnostic to a specific connector design and can be used with the 2.2-5, NEX10 or MQ4/MQ5. The MLOC solution is unique because it eliminates the need to use a torque wrench in the field, preventing issues from hand tightening the RF connectors.
Figure 5 Rosenberger NEX10-4 cluster connector. Source: Rosenberger.
Figure 6 CommScope MLOC-4 with NEX10 compatible cluster connector. Source: CommScope.
One unresolved issue with the current NGMN Alliance recommendation: it only covers the TDD mode, not FDD. 4-port multiport cluster connectors for FDD systems are quickly approaching, given the continued increase in the number of frequency bands, as well as 8 x 8 MIMO FDD.
5G NR DRIVES PASSIVE ANTENNA PORTS AND CONNECTORS
For 5G applications using a 1+1 antenna configuration for each sector, one position will be occupied by a high port count (>20) passive antenna supporting FDD and FDD + TDD modes, while the other position will be occupied by a mMIMO antenna radio system (MM-ARS), typically 32T32R or 64T64R (see Figure 7).
Figure 7 5G 1P + 1MM-ARS antenna configuration, each sector.
Figure 8 5G 1P + 1P antenna configuration, each sector.
Figure 9 Base station antenna RF connector port shipment trends, 2008–2018.
5G MM-ARS equipment is not inexpensive and is extremely power hungry. Considering capital and operating expenses, the least expensive way for a mobile operator to deploy 5G is to use a 1+1 configuration, replacing the MM-ARS with a traditional passive antenna (8T8R) and RRU (see Figure 8). This second antenna will only support the 5G frequency bands (typically, Band 41 at 2.5 GHz and Band 42 at 3.5 GHz). Current deployments in Europe and Asia are using 5G passive antennas in both dense urban and rural areas where the mobile traffic does not require an MM-ARS solution. A single band 5G NR passive antenna typically uses single-port connectors, for a total of nine: eight RF ports and one calibration port. Nine jumper cables are also required for this configuration. Either N-type or, more likely, 4.3-10 DIN connectors will be used for the antenna connectors, the jumper cables and the RRUs, the latter depending on the equipment manufacturer. A 5G NR 8T8R passive antenna requires a total of 36 RF connectors per sector to support the RRU, antenna and jumper cables - in addition to the multitude of RF connectors for the legacy antenna configuration.
MARKET TRENDS
EJL Wireless Research has been tracking base station antenna shipments and port counts since 2008. We believe we have the most extensive database of base station antenna shipments globally. From this, we extracted the total RF antenna port shipments each year to create a view of shipments over the past 10 years (see Figure 9). The dip in 2015 and 2016 largely reflects the completion of the 4G network in China. The rebound in 2017 and 2018 shows the emergence of 4 × 4 MIMO FDD LTE and dual-mode FDD/TDD antennas.
Figure 10 Relative RF cluster connector shipments, 2017–2018.
While 4.3/10 DIN connector shipments nearly tripled in 2018, legacy 7/16 DIN also increased by 10 percent. While all new antenna designs are using 4.3/10 DIN connectors, legacy antennas still use 7/16 DIN connectors; antenna manufacturers did not redesign and upgrade their legacy antennas with the new 4.3/10 DIN connectors as an option. Nearly all new RRU designs are using 4.3/10 DIN connectors, with some equipment manufacturers opting for the smaller NEX10 or 2.2/5 connectors.
Cluster connector shipments for the base station market have more than doubled from 2017 to 2018 (see Figure 10), and we expect continued growth from 2019 due to shipments of dual-mode FDD/TDD antenna solutions. The jumper cables to support RF cluster connectors are in a pigtail configuration, with one cluster connector at the antenna and single connectors at the RRU.
The following trends over the next five years will drive single-port and multiport cluster connectors in the base station infrastructure market:
- Migration from 2 × 2 MIMO (2T2R) RRUs to 4 × 4 MIMO (4T4R) RRUs supporting FDD LTE.
- Emergence and adoption of FDD 8 × 8 MIMO RRU technology for mid-band (1800 to 2700 MHz) frequencies.
- Adoption of high port count (>20) dual-mode, multi-band FDD/TDD antennas.
- Adoption of single- and dual-band TDD 5G NR 8 × 8 MIMO beamforming antennas.
- Use of the Citizens Broadband Radio Service (CBRS) spectrum in the United States, supporting 4 × 4 MIMO FDD.
The RF connector market, whether single connectors or multiport clusters will thrive. While the crossover point for unit shipments of the 4.3/10 DIN connector compared to the legacy 7/16 DIN connectors will eventually occur, we believe that 2020 or 2021 may be the time, as 2018 RF connector volumes heavily favored 7/16 DIN.
