浅谈5G中提到的的非正交接入技术(1)

An simple introduction for NOMA from power multiplexing to power diversity

Consider a downlink NOMA system, where a BS send a superimposed messages to two users simultaneously. Let $h_i$, $i=1,2$ denote the channel response of the users from the BS.

The received signal at user $i$ can be expressed as

$y_i=h_i(s_1+s_2)+n_i$,

where $s_i,i=1,2$ is the desired message of user $i$, and $n_i$ denote the noise at user $i$ and $n_i\sim \mathcal{C}\mathcal{N}(0,{\sigma }_i^2)$. Here, we assume that σ12=σ22=σ2\sigma_1^2 = \sigma_2^2 =\sigma^2σ12​=σ