Because the CDMA system is the interference-limited system, directional antennas are usually used for spatial isolation, which reduces interference. In a multisectorized cell using directional antennas, the call blocking occurs not only due to the insufficient number of CEs available for traffic channels in BSs but also due to a limit on the number of concurrent users in each sector ^[1]. The CE performs the baseband spread-spectrum signal processing for a given channel. For trunking efficiency, all CEs are provided per cell, and any CE can be assigned to any user in the cell regardless of sector. Call blocking due to insufficient CEs available for traffic channels in the BS is defined as hard blocking. So far, we assumed that the CDMA system of our interest has a sufficient number of CEs and the system only suffers from soft capacity issues. For example, in Chapters 7 and 8, the Erlang capacity of CDMA systems is already investigated based on only soft blocking for the case of multiclass services and the voice and data services under the delay constraint, respectively.

In this chapter, we will investigate the effect of a limited number of CEs in BSs on the Erlang capacity of CDMA systems supporting multiclass services as an expansion work of Chapters 7 and 8. In addition, a graphic interpretation method also will be presented for the case of multiple FAs, where the required calculation complexity of the exact method is too high to calculate the Erlang capacity.