Making a case of beamforming for commercial deployments

By : BP Tiwari
I have been observing emergence of new 4G technologies for last couple of years and one of the most talked multi antenna concepts is beamforming. BF is one of the much awaited technologies that helps operators to increase capacity in network and also helps in overall network quality by reducing interference in network.
Alcatel Lucent and Cisco-Navini would definitely take the lead in whatever little commercial beamforming that we have in the industry. IF we observe the WiMAX infrastructure supplier closely, we will recognize that ALU and CISCO were bullish about BF technology and hence their first products in WiMAX line were based on Beamforming. Obliviously the cost to produce a beamforming based base station is higher due to additional RF components required in the base stations In contrast other supplier like Huawei, ZTE, Samsung, Motorola, Alvarion etc started with MIMO based systems with intentions to deploy Beam forming at capacity grows in networks.
I have observed Navini’s beamforming systems which were based on 8TRX chains and that of Alcatel lucent’s based on 4TRX chains. The beam forming gains for both the systems can vary from 6-9 db in downlink.As a rule of thumb an additional 1 db gain can reduce 10% cell sites in coverage based deployment. However, Beamforming gains can only be applied in data channels and most of the time our link budgets are control channels limited. But obliviously if we have 3-6 db additional gains it will improve overall network quality by increasing CINR of each subscriber and hence an overall improvements in capacity.
Observation reveals that most of the WiMAX networks were deployed based on coverage initially than capacity. Also most of the WiMAX operators got has 30MHz or more WiMAX spectrum to take care of their initial capacity and wanted to keep initial investment low.
Infrastructure supplier like Huwaei, Samsung, Motorola, Alvarion and ZTE on similar line started their WIMAX deployment with 2×2 MIMO systems and with extending flexibility to add additional electronics for operators to improve capacity in similar amount of channel at later stage. This capacity gains could be in the range of 15 to 20% over 2×2 MIMO systems.
The good part is that we are seeing a harmonization towards beamforming support in industry with Hauwe, ZTE , Samsung , Motorola and Alvarion has plans for commercial release in next 12-18 months. In later case supplier were more comfortable in developing MIMO A & B in 2×2 Mode initially and later migrated to add 4×4 MIMO + CDD (Diversity ) with final destination to Beamforming+MIMO profiles. I hope that we will see some commercial beamforming systems in early 2011.

Thanks