Information Freshness in Uplink OFDM Based Multiple Access Networks in Flat Nakagami-$m$ Fading Channels

In flat Nakagami-
$m$
fading channels, we study the total information freshness maximization problem for an uplink orthogonal frequency division multiplexing (OFDM) based multiple access network. Without channel state information, each user transmits the freshest version of the file to the base station for information updating using the OFDM scheme. Considering the actual transmission durations, we theoretically derive the analytical expression for average information freshness. Furthermore, we propose an alternating optimization algorithm to solve the total information freshness maximization problem. In the proposed algorithm, the bandwidth allocation problem is solved using the majorization-minimization based iterative algorithm and transmission rate optimization problem is solved by the bisection search. Numerical results illustrate that our proposed updating scheme is superior to the rate proportional and rate inverse proportional updating schemes.