Browsing by Author "Su, Wun-Ci"

Now showing 1 - 5 of 5

Analytical Modeling and Design of Energy Efficient Class-Selection for Long Range Wide Area Networks
(2019-01-01)
Su, Wun-Ci
;
Wu, Tzu-I
;
Li, Pei-Rong
;
Feng, Kai-Ten
;
電信工程研究所
Long range wide area networks (LoRaWAN) is one of the novel specification for the applications of Internet-of-Things. Recent research focused on the propagation model and coverage discussion based on experimental measurement. In this paper, power-class analytical model is firstly proposed to model the operations of LoRaWAN end-devices for throughput and power consumption. Based on this model, the energy efficient class-selection algorithm (EECA) is proposed to achieve the optimal energy efficiency with the consideration of power consumption on end-devices by the suitable class selection scheme. A system level simulation has been conducted for performance evaluation. The simulation results provide the guideline for system parameters configuration and class selection on each end-devices under different scenarios.
Comprehensive Performance Analysis and Sleep Window Determination for IEEE 802.16 Broadband Wireless Networks
(2016-01-01)
Feng, Kai-Ten
;
Su, Wun-Ci
;
Chen, Chun-Yu
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
The IEEE 802.16 standard is developed to support services with high data rate and high mobility for the next generation broadband wireless access networks. There are existing sleep mode operations specified in the series of IEEE 802.16 standards in order to provide energy conservation for the mobile devices. In this paper, the analytical models for sleep mode operations of both the IEEE 802.16e and IEEE 802.16m standards are proposed, respectively. The effects of both downlink and uplink traffic are properly considered in the proposed models. Simulations are performed in order to validate the effectiveness of proposed system models. However, according to the performance evaluation for IEEE 802.16e/m system, inefficiency is observed which can be resulted from specific mechanisms within the sleep mode operations, such as frequent state transitions, under-utilized listening windows, and the adoption of binary-exponential growth of sleep window size. A POMDP-based sleep window determination (PSWD) approach is proposed in this paper, which stochastically determines the adequate length of each sleep window according to the traffic pattern. Based on the estimated traffic state, an energy cost-based sleep window determination policy is provided within the PSWD approach in consideration of tolerable network delays. Simulation results show that the proposed PSWD approach outperforms conventional IEEE 802.16e/m power-saving mechanisms in terms of energy conservation while the delay constraints are also satisfied corresponding to various traffic demands.
Design and Analysis of Traffic-Based Discontinuous Reception Operations for LTE Systems
(2017-12-01)
Feng, Kai-Ten
;
Su, Wun-Ci
;
Yu, Yu-Ping
;
電機工程學系
;
Department of Electrical and Computer Engineering
The 3GPP long term evolution (LTE) system is developed to enhance mobile services from the former 3G systems. In order to prolong the battery life time of mobile devices, the discontinuous reception (DRX) scheme is specified in the LTE standard to reduce the power consumption of user equipment. Existing analytical models did not comprehensively consider all essential sleep mode behaviors. Therefore, a performance analysis, including major DRX parameters is proposed in this paper for sleep mode operation. The correctness of proposed model is validated and the improvement can be observed via simulations. Furthermore, according to proposed analytical model, the DRX parameters can significantly influence the power-saving efficiency and quality-of-service (QoS) of LTE system. Hence, a traffic-based DRX cycles adjustment (TDCA) scheme is proposed to adaptively adjust the sleep cycles to balance the sleep ratio and mean packet delay based on traffic estimation. A partially observable Markov decision process is employed to conjecture the present traffic status. The policy for selecting DRX parameters can be constructed-based the evaluation metrics in TDCA scheme. Simulation results show that the proposed TDCA scheme can enhance the energy-saving efficiency while the QoS constraint is still satisfied.
QoS-Guaranteed Channel-Aware Scheduling and Resource Grouping under Non-full Buffer Traffic for LTE-A Networks
(2017-01-01)
Cheng, Ya-Hsuan
;
Su, Wun-Ci
;
Feng, Kai-Ten
;
Wang, Li-Chun
;
電機工程學系
Scheduler plays an important role for long term evolution-advanced (LTE-A) system to achieve high throughput performance. Existing research work on scheduler design did not fully consider non-full buffer capacity at the base station (BS) owing to the fluctuation on data volume. In this paper, we proposed a quality-of-service (QoS) guaranteed channelaware (QGCA) scheduler with the consideration of BS buffer status to improve system capacity. The proposed QGCA scheme fully considers the required components for LTE-A scheduler, including resource grouping along with modulation and coding scheme. Moreover, we proposed an adaptively channel-aware resource grouping (CARG) method within the QGCA scheduler for improving the performance of existing resource grouping schemes. Numerical results show that our proposed QGCA scheduler and CARG scheme outperform conventional methods, especially under non-full buffer and delay-sensitive VoIP traffic.
QoS-Guaranteed Power-Saving Configuration Prediction Scheme for 5G IoT
(2017-01-01)
Su, Wun-Ci
;
Feng, Kai-Ten
;
電機工程學系
;
Department of Electrical and Computer Engineering
The narrowband Internet-of Things (NB-IoT) standard has been developed to provide low data rate requirement for 5G IoT systems. To prolong the battery lifetime of user equipment (UE), the extend discontinuous reception (eDRX) and power saving mode (PSM) are specified in the standard for power efficient purpose. However, it is non-trivial to configure suitable power-saving parameters to achieve power conservation while reducing transmission latency. In this paper, we proposed a QoS-guaranteed power-saving configuration prediction (QPCP) scheme to effectively reduce system power consumption with guaranteed packet delay constraints. By adopting partially observable Markov decision process (POMDP) and scheduling of base station (BS), a feasible set of power-saving parameters can be obtained. Simulation results show that the proposed QPCP scheme outperforms other existing methods for power-saving of both UE and BS with guaranteed QoS constraints.