LTE Advanced

About: LTE Advanced is a research topic. Over the lifetime, 4055 publications have been published within this topic receiving 74262 citations. The topic is also known as: Long-Term Evolution Advanced & LTE-A.

Experimental Evaluation on Throughput Performance of Asymmetric Carrier Aggregation in LTE-Advanced

Abstract: This paper presents laboratory experimental results on the throughput performance of asymmetric carrier aggregation between the uplink and downlink using an LTE-Advanced testbed. The implemented base station (BS) and mobile station (MS) transceivers have transmission bandwidth capability of up to 100 MHz (5 component carriers (CCs)) and 40 MHz (2 CCs) in the downlink and uplink, respectively. The testbed also features CC-specific adaptive modulation and channel coding (AMC) and hybrid automatic repeat request (HARQ) functionalities based on the actually transmitted control signaling. The experimental results show that, in the uplink, CC-based AMC using up to 64QAM high-order modulation is effective in increasing the user throughput in multipath fading channels and achieves a throughput greater than 100 Mbps using carrier aggregation with 2 CCs and 1-by-2 SIMO. The results also show that when the uplink control information (UCI) corresponding to 5 downlink CCs is multiplexed onto the uplink shared channel (PUSCH), the required block error rate (BLER) of the UCI below 10-2 is almost satisfied by appropriately setting the offset value, , for adjusting the channel coding rate of UCI although AMC with high-order modulation is applied to the UCI as well. Furthermore, we show that when carrier aggregation with 5 CCs and 2-by-2 MIMO multiplexing are applied in the downlink, high throughput greater than 500 Mbps (thus, half of the 1 Gbps that can be achieved using 4-by-4 MIMO multiplexing) is achieved at the average received signal-to-noise power ratio (SNR) of approximately 25 dB when CC-specific AMC considering UCI error is applied

Energy-saving strategy for green cognitive radio networks with an LTE-advanced structure

Abstract: A green cognitive radio network (CRN), characterized by base stations (BSs) that conserve energy during sleep periods, is a promising candidate for realizing more efficient spectrum allocation. To improve the spectrum efficiency and achieve greener communication in wireless applications, we consider CRNs with an long term evolution advanced (LTE-A) structure and propose a novel energy-saving strategy. By establishing a type of preemptive priority queueing model with a single vacation, we capture the stochastic behavior of the proposed strategy. Using the method of matrix geometric solutions, we derive the performance measures in terms of the average latency of secondary user (SU) packets and the energy-saving degree of BSs. Furthermore, we provide numerical results to demonstrate the influence of the sleeping parameter on the system performance. Finally, we compare the Nash equilibrium behavior and social optimization behavior of the proposed strategy to present a pricing policy for SU packets.

How accurate is the RACH procedure model in LTE and LTE-A?

Abstract: In Long Term Evolution (LTE) networks, User Equipments (UE)s should proceed Random Access CHannel (RACH) procedure to attach to the Base Station and access the channel. One limitation of this procedure is the congestion that may appear when high number of UEs are simultaneously trying to attach to the channel. Such use-case happens when high number of Machine Type Communication (MTC) devices are deployed in one LTE cell. In order to evaluate the RACH performances, in terms of success, collision and idle probabilities, when the traffic load is high, accurate models are needed. However, most of existing models ignore one important constraint, which is the fact that the eNB can knowledge only a limited number of UEs in each RACH round, leading to a mis-formulation of these metrics in the context of LTE, and especially in the presence of high number of devices competing for the channel access. In this paper, we tackle the above-mentioned issue by devising a new model for the RACH procedure taking in consideration this constraint. Computer simulation demonstrates that unlike the existing models, our proposed model achieve high accuracy to estimate the performance of the RACH procedure, whatever the traffic load.

Users' classification-based call admission control with adaptive resource reservation for LTE-A networks

Abstract: The Long Term Evolution (LTE) Advanced (LTE-A) has been put in place to support diverse IP-based traffic, such as voice, data and multimedia. From the network operator's point of view, differentiation of users is becoming an important issue because quality of service (QoS) and privilege levels vary among users and their traffic classes. The main objective of the network operators is to maximize the revenue earned by having maximum network utilization, at the same time guaranteeing the agreed-upon QoS to the users and their traffic classes. An important aspect for achieving these objectives is to design an effective CAC scheme with users' varying privileges and QoS requirements.In this paper, we introduce the user's privileges and traffic maximum delay tolerance as additional dimensions in the call admission control processes to efficiently control the utilization of LTE-A network resources. Based on this idea, we propose an efficient call admission control scheme named "delay aware and user categorizing-based CAC with adaptive resource reservation (DA-UC-ARR)", where the user priority is adjusted dynamically based on the current network conditions and the users' categorizations and traffic delay tolerances, to increase the network's resource utilization and at the same time to maximize the operators' revenue. In this proposed scheme, the users are classified into Golden users and Silver users, and the type of service per user is classified as real time (RT) and non-real time (NRT) services. We compare the performance of the proposed scheme with the corresponding results of previous schemes, referred to as the adaptive resource reservation-based call admission control (ARR-CAC) (Andrews et al., 2010; AlQahtani, 2014), where user categorization and delay were not taken into consideration in the call admission control process. Simulation results indicate the superiority of the proposed scheme because it is able to achieve a better balance between system utilization, users' privileges provided by network operators and QoS provisioning compared to the ARR-CAC scheme.

Tower overlay over LTE-Advanced+ (TOoL+): Results of a field trial in Paris

Abstract: The system “Tower Overlay over LTE-Advanced+ (TOoL+)” is a solution developed to support mobile access networks to cope with the exponentially growing data traffic by offloading popular data to an LTE-based broadcast carrier transmitted from a High Tower, High Power (HTHP) infrastructure. As LTE-Advanced is specified for Low Tower, Low Power cellular networks, the term LTE-A+ reflects proposed additional features to the LTE standard like longer cyclic prefixes that are necessary to support the HTHP broadcast environment. Cooperative spectrum use can be achieved by transmitting LTE-A+ within DVB-T2 Future Extension Frames, forming a hybrid time-division multiplexed carrier whose capacity can be flexibly allocated to DVB-T2 and LTE-A+, respectively. This paper presents a field trial deployed in Paris, France, to evaluate TOoL+ in a demanding environment. The physical layer performance of different LTE-A+ broadcast modes and time-division multiplexing configurations is compared to that of LTE-Advanced and DVB-T2. Results show that LTE-A+ is suitable for an HTHP broadcast application and that the coverage area of LTE-A+ is similar to that of DVB-T2 when similar modulation and coding schemes are applied.