Rumors indicate that the iPhone 6S won't look very different on the outside, but that Apple is keen on building it to be faster and more battery efficient.
It could push LTE download speeds from the current 150Mpbs max to a new 300Mbps ceiling. That's likely faster than your at-home router's maximum download speed.
Of course, as 9to5Mac correctly points out, the speeds are likely to be much lower in real-life tests due to unfortunate limitations of cellular networks, and upload speeds are slated to stay the same.
iPhone 6S battery life hints
Qualcomm's LTE chip is said to be more energy efficient, so leaving your home WiFi network won't put as much of a strain on the Apple smartphone.
Better yet, the purported iPhone 6S motherboard is also said to be smaller, which would give Apple extra room to fit a larger battery into the new phone.
The 4.7-inch iPhone 6 has a 1,810 mAh mAh capacity battery, while the 5.5-inch iPhone 6 Plus has a 2,915 mAh battery.