Equivalent capacity analysis of LTE-Advanced systems with carrier aggregation

The Long Term Evolution - Advanced (LTE-A) standard is widely accepted for the 4th generation mobile systems to satisfy the explosive growth of high-data-rate demand. Carrier Aggregation (CA) is considered as one of the most momentous techniques adopted in LTE-A standard. Many studies have been done to analyze the performance of LTE-A systems with CA in terms of average user throughput. However, the system-level capacity analysis of LTE-A systems has not been well studied. In this paper, we explore the downlink admission control process in LTE-A systems with CA to compare the capacities between LTE users and LTE-A users, based on the metric - equivalent capacity. Specifically, taking into account the user heterogeneity, the system evolution is modeled as a birth-death process for each user class based on an effective user traffic generation model. A closed-form relationship between the equivalent capacity and system bandwidth is then derived for a single-carrier LTE-A system with the help of binomial-normal approximation. The relationship is further extended to multi-carrier case for both LTE users and LTE-A users. Finally, simulation results are provided to verify our analytical ones, and demonstrate that the equivalent capacity of LTE-A users surpasses that of LTE users significantly.