  Non-orthogonal multiple-access (NOMA) is a leading technology which gain a
lot of interest this past several years. It enables larger user density and
therefore is suited for modern systems such as 5G and IoT. In this paper we
examined different frame-based codes for a partially active NOMA system. It is
a more realistic setting where only part of the users, in an overly populated
system, are active simultaneously. We introduce a new analysis approach were
the active user ratio, a system's feature, is kept constant and different sized
frames are employed. The frame types were partially derived from previous
papers on the subject [1][2] and partially novel such as the LPF and the
Steiner ETF. We learned the best capacity achieving frame depends on the active
user ratio and three distinct ranges where defined. In addition, we introduced
a measure called practical capacity which is the maximal rate achieved by
simple coding scheme. ETFs always achieve the best practical capacity while
LPFs and sparse frames are worse than a random one.
