  In this paper, we develop optimal energy-bandwidth allocation algorithms in
fading channels for multiple energy harvesting transmitters, each may
communicate with multiple receivers via orthogonal channels. We first assume
that the side information of both the channel states and the energy harvesting
states is known for $K$ time slots {\em a priori}, and the battery capacity and
the maximum transmission power in each time slot are bounded. The objective is
to maximize the weighted sum-rate of all transmitters over the $K$ time slots
by assigning the transmission power and bandwidth for each transmitter in each
slot. The problem is formulated as a convex optimization problem with ${\cal
O}(MK)$ constraints, where $M$ is the number of the receivers, making it hard
to solve with a generic convex solver. An iterative algorithm is proposed that
alternatively solves two subproblems in each iteration. The convergence and the
optimality of this algorithm are also shown. We then consider the special case
that each transmitter only communicates with one receiver and the objective is
to maximize the total throughput. We develop efficient algorithms for solving
the two subproblems and the optimal energy-bandwidth allocation can be obtained
with an overall complexity of ${\cal O}(MK^2)$. Moreover, a heuristic algorithm
is also proposed for energy-bandwidth allocation based on causal information of
channel and energy harvesting states.
