Equation (12) means that the system is stable only when the equivalent bandwidth occupied by all calls in the system is less than the system bandwidth.
Equation (20) as well as equation (12) expresses the equivalent spectral bandwidth restriction of LTE and WLAN systems: The prerequisite for guaranteeing the QoS of calls and stability of the systems is that the equivalent bandwidth occupied by all calls in the system should be less than the system bandwidth.
in] opt] into equation (18), we get the optimal equivalent bandwidth for a certain class of service:
statistical time slots in WLAN, power and sub-carriers in OFDMA, occupied by calls according to their QoS requirements have been mapped into equivalent bandwidth.
i] is the equivalent bandwidth requirement of service class [[PHI].
Therefore, this function, as a reference revenue function, is proved to be rational to reflect the difference between the allocated equivalent bandwidth and the equivalent bandwidth requirement.
In this condition, the residual system bandwidth resources calculated based on equivalent bandwidth in either RAT are sufficient to accept a new incoming call.
2 shows that the equivalent bandwidth occupied by a call increases with the rising of system load (in terms of number of voice users, where the number of data users is fixed at 10) .
3 depicts the equivalent bandwidth required for voice calls varying with their allocated power levels in LTE system.
For the collision reason, the required equivalent bandwidth for a single call in WLAN increases with the rising number of admitted calls.
In this paper, we firstly propose a new resource denotation method based on equivalent bandwidth mapping concept in order to uniform the expression of resources in WLAN and LTE heterogeneous networks.