Since 2016, India has been trying its best to make contributions to the process of the global 5G technology development process. In alignment with this aspiration, it presented a concept titled low mobility large cell (LMLC) in the ITU meeting held in Geneva in Oct 2016 (WP 5D #25). This proposal was further sharpened (evaluation configuration & spectrum efficiency targets) in a follow-up meeting held in the same venue in Feb 2017 (WP 5D #26). Subsequently, these contributions got included in the final ITU documents – M2410, M2411 & M2412 at the end of 2017. These ITU documents lay the foundation for submission and evaluation of prospective 5G technologies proposed by stakeholders. India, through TSDSI, also submitted its technology, which later got evaluated by various stakeholders for suitability to be considered as 5G technology. The purpose of this note is to identify the opportunities and challenges being faced by India while it goes through this process.
What is LMLC?
In order for us to appreciate India’s current situation, we need to first understand what LMLC is all about. It is nothing but a toned-down requirement (configuration “c”) defined for evaluation in M2412 for rural eMBB settings only for the 700 MHz band (pages 23 and 24). The idea is to stretch the intersite distance (ISD) much beyond (6 kms) than what is possible under the conventional setting (1.732 kms) in the same band (configuration “a”). This is made possible by diluting some performance requirements like UE speed of interest (from 500 km/h to 30 km/h), thereby enabling stretching of the coverage of BTS compared to its counterpart (configuration “a”). By doing so the cost of deployment can be reduced significantly. Surprisingly, while doing so, the 5th percentile user spectrum efficiency number (evaluating network performance at the cell edge) was done away with. And for the evaluation purpose, only average spectrum efficiency (50th percentile number) was relied upon (table 1 page 4 of M2410). Here, it also important to point out that no discussion happened on 3.5 GHz band for LMLC at the time when evaluation, configuration, and spectrum efficiency numbers for LMLC were being frozen. Hence, one has to conclude that LMLC with 6 Kms ISD (defined in ITU) was only for the 700 MHz band and NOT for any other band.
