In order to satisfy the requirements of future IMT-Advanced mobile systems, the concept of spectrum aggregation is introduced by 3GPP in its new LTE-Advanced (LTE Rel. 10) standards. While spectrum aggregation allows aggregation of carrier components (CCs) dispersed within and across different bands (intra/inter-band) as well as combination of CCs having different bandwidths, spectrum aggregation is expected to provide a powerful boost to the user throughput in LTE-Advanced (LTE-A). However, introduction of spectrum aggregation or carrier aggregation (CA) as referred to in LTE Rel. 10, has required some changes from the baseline LTE Rel. 8 although each CC in LTE-A remains backward compatible with LTE Rel. 8. This article provides a review of spectrum aggregation techniques, followed by requirements on radio resource management (RRM) functionality in support of CA. On-going research on the different RRM aspects and algorithms to support CA in LTE-Advanced are surveyed. Technical challenges for future research on aggregation in LTE-Advanced systems are also outlined.

A Survey of Radio Resource Management for Spectrum Aggregation in LTE-Advanced

With the design of data communications in mind, 3GPP LTE-advanced (LTE-A) is probably the most promising technology for Internet of Things (IoT). For IoT applications, continuous low-rate streaming data may be reported from devices over a long period of time, imposing stringent requirements on power saving. To manage power consumption, 3GPP LTE-A has defined the discontinuous reception/transmission (DRX/DTX) mechanism to allow devices to turn off their radio interfaces and go to sleep in various patterns. Existing literature has paid much attention to evaluate the performance of DRX/DTX; however, how to tune DRX/DTX parameters to optimize energy cost is still left open. This paper addresses the DRX/DTX optimization, by asking how to maximize the sleep periods of devices while guarantee their quality-of-service (QoS), especially on the aspects of traffic bit-rate, packet delay, and packet loss rate in IoT applications. Efficient schemes to optimize DRX/DTX parameters and schedule devices' packets with the base station are proposed. The key idea of our schemes is to balance the impacts between QoS parameters and DRX/DTX configurations. Simulation results show that our schemes can guarantee traffic bit-rate, packet delay, and packet loss rate while save energy of user equipments .

An Energy-Efficient Sleep Scheduling With QoS Consideration in 3GPP LTE-Advanced Networks for Internet of Things

Full length article: LTE-Advanced and the evolution to Beyond 4G (B4G) systems

Fiber-Wireless (FiWi) network, as an integration of optical fiber network and wireless access network, has attracted intensive research interest and enjoyed significant growth in its applications over the last two decades. Besides bringing great opportunities for the development of FiWi networks, the new applications and techniques, like the emerging Internet of Things (IoT), raise unprecedented challenges in different aspects of FiWi integration. Based on such observation, we provide in this paper a comprehensive survey of recent progress and ongoing research works in the aspects of network architecture, QoS provisioning, scalability improving, reliability enhancing, energy saving, as well as standardization activities and case studies. Furthermore, new trends and challenging issues on future smart FiWi networks are identified and discussed in details.

New Perspectives on Future Smart FiWi Networks: Scalability, Reliability, and Energy Efficiency

Discontinuous reception (DRX) saves battery power of user equipment (UE) usually at the expense of potential increase in latency in the Long Term Evolution (LTE) networks. Therefore, an optimization is needed to find the best tradeoff between latency and power saving. In this paper, we first develop an analytical model to estimate power saving achieved and latency incurred by DRX mechanism for active and background mobile traffic. A tradeoff scheme is then formulated to maintain a balance between these two performance parameters based on operator's preference for power saving and latency requirement of traffic. The analytical model is validated using system level simulation results obtained from OPNET Modeler. The results show that the proposed tradeoff scheme is efficient in keeping a balance between power saving and latency. The results also indicate that DRX short cycles are very effective in reducing latency for active traffic, while shorter inactivity timer is desirable for background traffic to enhance power saving. We also proposed a mechanism to switch DRX configuration based on traffic running at UE, using UE assistance procedure recently adopted by 3GPP in Release 11. DRX configuration switching increases the power saving significantly without any noticeable increase in latency of active traffic.

Device Power Saving and Latency Optimization in LTE-A Networks Through DRX Configuration

In order to meet the requirement of wider bandwidth in IMT-Advanced, carrier aggregation (CA) is introduced by 3GPP to support bandwidth up to 100MHz in its LTE-Advanced standards. An LTE Rel.10 UE can aggregate up to 5 component carriers (CCs) simultaneously, but may be assigned only part of the total available CCs depending on its capability or traffic load. Thus, a proper CC selection method is necessary. First, two traditional CC selection methods respectively named Random and Round Robin CC selection are investigated, which can well balance the load across different CCs. However, neither of them is suitable for non-continuous CA scenarios through our analysis. To solve this problem, an improved CC selection method for non-continuous CA is proposed in this paper. Simulation results demonstrate that the proposed method outperforms both of the traditional ones.

Improved Component Carrier Selection Method for Non-Continuous Carrier Aggregation in LTE-Advanced Systems

The discontinuous reception (DRX) mechanism is adopted by the Third Generation Partner Project (3GPP) Long Term Evolution (LTE) as a promising technology to extend the user equipment's (UE's) battery lifetime. From our simulation, it can be found that the decrease in power consumption resulted from LTE DRX is always at the price of deteriorated system utility. Thus, this paper focuses on the design of an improved DRX configuration method to provide higher power efficiency. The single threshold adaptive configuration DRX mechanism (S-ADRX) is proposed to guarantee the system utility at the cost of extra energy consumption. Based on S-ADRX, a novel multi-threshold adaptive configuration DRX mechanism (M-ADRX) is presented, which is able to save as much power as possible while maintaining the system utility without any additional signaling overhead. Simulation results indicate that the proposed M-ADRX mechanism outperforms the current LTE DRX.

A More Power-Efficient Adaptive Discontinuous Reception Mechanism in LTE

The invention discloses a method of adjusting a community coverage area in a communication system, a base station and a low-power node. The method includes obtaining first communication performance parameters of one or more users served by a first device through the first device, and receiving second communication performance parameters of one or more users served by a second device, wherein the second communication performance parameters are emitted by the second device, the first device and the second device are respectively one of the normal base station and the low-power node; obtaining a first threshold value and a second threshold value not less than the first threshold value by means of the first communication performance parameters, and respectively comparing the first threshold value and the second threshold value through the second communication performance parameters; when the second communication performance parameters are less than a first coverage adjusting threshold value, confirming an adjusting mode to be reducing an offset value in a current community coverage expansion scheme of the low-power node; or when the second communication performance parameters are larger than a second coverage adjusting threshold value, confirming the adjusting mode to be increasing the offset value in the current community coverage expansion scheme of the low-power node; and informing the adjusting mode to the second device.

Gao Songtao

Papers

Improved Component Carrier Selection Method for Non-Continuous Carrier Aggregation in LTE-Advanced Systems

A More Power-Efficient Adaptive Discontinuous Reception Mechanism in LTE

Method of adjusting community coverage area in communication system, base station and low-power node

Discontinuous reception control method

Method and device for allocating member carrier waves