Abstract
In Long Term Evolution-Advanced (LTE-A), the signal quality in a wireless channel is estimated based on the channel quality measurements. The measurement results are used to select suitable modulation and coding scheme for each transmission, feedback, and processing delay, which can cause a mismatch between channel quality information (CQI) and current channel state at the base station. However, prospect delays in the reception of such CQI may lead to a system performance degradation. This study analyzes the impact of CQI feedback delay on joint user scheduling (JUS) scheme and separated random user scheduling (SRUS) scheme in LTE-A system over carrier aggregation. The analysis will be compared with the system having delayed channel and perfect knowledge at different deployment scenario. We will study the throughput performance of both scheduling schemes with different deployment scenario, and then recommend the suitable deployment scenario to keep the desired QoS for a specific number of users. Results show that, in main beam directed at sector boundaries and diverse coverage, JUS scheme performs better than SRUS, which can justify the intensive use of user equipment power and extra control signaling overhead.
Highlights
It has been suggested carrier aggregation (CA) as a technique in Long Term Evolution-Advanced (LTE-A), LTE-A system to enhance the data rate of the user [1,2,3,4]
The performance is evaluated in terms of per-UE average throughputs with channel quality information (CQI) feedback delay on both scheduling schemes separated random user scheduling (SRUS) and joint user scheduling (JUS) in CA deployment scenarios main beam directed at sector boundaries scenarios and diverse coverage scenarios
In main beam directed at the sector boundary deployment scenario, the eNB antennas for different component carriers (CCs) can have various beam directions patterns
Summary
It has been suggested carrier aggregation (CA) as a technique in LTE-A, LTE-A system to enhance the data rate of the user [1,2,3,4]. If separated random user scheduling algorithm is adopted, the eNB calculates the user throughput in single CC, so the complexity is smaller than JUS algorithm. It is measured from the reference symbols transmitted by e-Node-Bs. In the CQI measurement interval, resolution is measured in the frequency domain, reporting mechanisms, and so forth. The performance is evaluated in terms of per-UE average throughputs with CQI feedback delay on both scheduling schemes SRUS and JUS in CA deployment scenarios main beam directed at sector boundaries scenarios and diverse coverage scenarios. The paper recommends the suitable scenario, in which aperiodic CQI reports should be deployed to maintain the desired level of quality of service (QoS) for a given number of users. This study can provide an appropriate guideline for possible CA combinations and operations in upcoming beyond fourth generation mobile communications
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