Why does it seem most of people will optimize the downlink rate,not the uplink rate? I search for some papers about energy harvest,SWIPT and optimization.And i found that there is just one paper to optimize the uplink rate,the others are for optimizing the harvested power,power budget in the transmitter or downlink rate.

So i want to ask why ? why do most of researchers won't optimize the uplink rate?is there any reason or difficulty?

Because in IoT,we may control lots of things,and of course we do need to know some information of the devices or what happened with the devices,that is ,we do need to know some feedback about the device,so we need  the device uplink the information back to the transmitter,so i think optimizing the uplink rate is still a worth research topic,why  why do most of reseachers optimize the downlink rate instead of uplink rate?

By the way,i also want to ask is the throughput the same as the rate?what is the difference between the throughput and capacity?
This simply reflects the load asymmetry of real world applications. On most networks, traffic is dominated by content streaming, which is a download activity. Netflix alone accounts for 15% of the world's entire Internet traffic.