This paper studies optimal allocation of resources to users in a fading broadcast channel (BC) to support heterogeneous traffic. Resource allocation is done in a cross-layer manner for both deadline-sensitive (DS) and best-effort (BE) data to provide users guaranteed Quality of Service (QoS). Given the user queue-states, the proposed algorithm allocates the minimum resource to 'just' meet the deadlines for DS packets a fixed % of time. The remaining resources are then optimally split between the users for their BE data to maximize sum-rate, minimize buffer holding cost or any general utility function. The resource allocation problem is formulated as a linear program (LP) followed by a geometric program (GP) which can be solved very efficiently. Simulation results are presented for Poisson packet arrivals and exponentially distributed packet lengths on a Rayleigh fading channel for both the DS and BE traffic.