The stage is set for the biggest ever spectrum auction in India, a country where operators need new capacity more than anywhere in the world. But the largest MNOs have seen growth in data usage slowing recently, so they will need to use the new 4G spectrum to tempt consumers and businesses with strong new services, or risk yet another price war. The Indian government has approved the proposal, from regulator TRAI, for a huge auction, which would be held in September. It will cover seven frequency bands, including the much-coveted 700 MHz spectrum for LTE, plus the 800 MHz, 900 MHz, 1.8 GHz, 2.1 GHz, 2.3 GHz and 2.5 GHz bands. It could raise a record INR5.6 trillion ($85bn)…