Performance evaluation of joint processing coordinated multipoint transmission in LTE networks

The purpose of the paper is to examine if public long term evolution (LTE) network is suitable for smart grid (SG) automatic metering usage, in a suburban scenario, without causing significant hindrance to typical LTE traffic. In addition, the same generalized suburban scenario is evaluated with a hybrid sensor - LTE network where wireless sensor network (WSN) cluster heads are also equipped with LTE remote terminal units (RTUs). The simulation topology is formed as a suburban area that consists of single RTU per apartment/house for SG traffic and an average 3.7 people per habitat, each with their user equipment, using one of the available carriers. Normal SG traffic is generated in both directions, uplink and downlink. The worst-case usage factor is considered as a power outage, where all SG meters in the area of influence simultaneously detect and attempt to report such a failure. Thus, emergency SG traffic is generated simultaneous by all RTUs. To alleviate the problem of the high momentary SG emergency traffic load, two distinct solutions are proposed and simulated. As the first solution, an artificial, up to one-second random delay is introduced in the transmission scheduling of emergency messages. The second solution applies low-power WSNs at the cluster level and cluster heads that contain both 802.15.4 and LTE communication interfaces, i.e., a hybrid sensor-LTE network. The simulation results show that both of the solutions that try to alleviate the high instantaneous traffic loads can reach the quality of service criteria for SG traffic without compromising other public LTE traffic. The deciding factor to use either pure LTE approach or a hybrid sensor-LTE network comes from non-functional requirements of the system.

One of the critical components of the Smart Grid (SG) is the Smart Meter (SM), which reports power consumption to a centralized control center at regular intervals. The Long Term Evolution (LTE) network has received much attention as a promising platform for SG communications due to its high bandwidth and low latency over a large coverage area. Nevertheless, when a huge number of SMs access the LTE network, the preamble collision becomes an issue. The negative effects of preamble collision are packet loss, delay, reestablishment attempts, and physical channel utilization, which degrade the performance of the LTE network. Hence, a Random Access (RA) mechanism is required for preamble signature to occupy Resource Blocks (RBs) for SMs. In this paper, we introduce a hybrid procedure that combines contention and non-contention based random access methods. The significance of this method is that, although SMs have fixed periodic communications, preamble signatures do not need to be reserved. The simulation results are compared with LTE standard. Packet loss is reduced by approximately 43%. SM latency is decreased by 11 ms at 90% of probability delay. Re-establishment attempts are lower than standard by proximately 76%. Finally, physical channel utilizations are reduced by around 3%.

ABSTRACTThe performance of 3GPP long term evolution (LTE) network can be significantly influenced by unbalanced user distribution. In heavily loaded cells, users cannot obtain satisfied services because of shortage of resources, whereas in lightly loaded cells, there are plenty of unoccupied resources. Load balancing (LB) is proposed to deal with this problem, through which the load distribution among nearby cells can be greatly balanced. However, because of the usage of full frequency reuse in LTE, the cell‐edge throughput is severely deteriorated by strong intercell interference. Meanwhile, LTE network usually serves users with heterogenous quality‐of‐service (QoS) requirements, which requires LB to be aware of it. Furthermore, call admission control (CAC) is indispensable in the process of LB, and it depends heavily on the long‐term average performance of the scheduling scheme. Thus, design of an efficient LB algorithm with the consideration of intercell interference, QoS, CAC and scheduling together becomes an important issue. To deal with the previous problem, a multi‐objective optimisation problem is formulated in this paper. Its complexity is analysed, and a practical algorithm, which includes hybrid scheduling, QoS‐guaranteed CAC, QoS‐aware intracell and intercell LB, is proposed. Extensive simulations are conducted. Results show that the proposed algorithm can approximate the optimal solution efficiently, thus leading to significantly better performance, that is, a lower new call blocking rate for users with QoS requirement, a larger total utility and a higher cell‐edge throughput for users without QoS requirement, although the cost is a bit degradation of the total throughput. Copyright © 2013 John Wiley & Sons, Ltd.

This paper evaluated the effects of third order Intermodulation Distortion (1MD3) on the Long Term Evolution (LTE) receiver due to coexistence between LTE and GSM networks. Amongst the various existing IMD orders which include first order, second order, third order, fifth order and seventh order. Third order is known to have the greatest distortion effects on a receiver due to its strength and its proximity to the frequency band of interest. It occurs as a result of the non-linear behavior of components or circuit at both the transmitter and receiver ends of wireless communication networks. IMD has potential negative effects on a victim receiver which majorly leads to increase in noise floor level and system capacity degradation. Deterministic approach was implemented in the work assuming worst case scenario. MATLAB software simulation was deployed to evaluate the capacity loss at the receiver end relative to a range of distances apart. Results obtained showed severe uplink capacity degradation when VISAFONE LTE network was interfered by INTERCELLULAR LTE downlink and ETISALAT GSM uplink. Various distances ranging from 500m to 3000m were varied between the ETISALAT GSM network and the VISAFONE LTE network. The results obtained showed that at 500 meters, the percentage capacity degradation was as high as 80. The least percentage capacity loss was obtained as 5.97 at 3000 meters.

The Long Term Evolution (LTE) standards are generated by the Third Generation Partnership Project (3GPP) for the Fourth Generation (4G) wireless communication systems. The Fourth Generation (4G) wireless communication standards use new physical layer signaling techniques in their physical layer. Single Carrier Frequency Division Multiple Access (SC-FDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) are the two major signaling techniques used in LTE. OFDMA is used in the downlink of the Fourth Generation (4G) wireless communication systems for its high spectral efficiency and SC-FDMA is used in the uplink of the Fourth Generation (4G) wireless communication systems for its high power efficiency. The main objective of this paper is to design and implement the reliable and energy efficient architecture for LTE uplink system using FPGA. IFDMA is the most energy efficient subcarrier mapping scheme of SC-FDMA multiple access scheme. In IFDMA, the data symbols subcarrier mapping is not one to one instead each subcarrier carries a part from each data symbol transmitted at that time instant. The reason for the selection of IFDMA subcarrier mapping along with SC-FDMA multiple access scheme for LTE uplink comes mainly from its advantage to provide a low peak to average power ratio (PAPR) for the transmitted waveform. This results in less power consumption in the mobile station during uplink transmission. The reliability of the system is improved using interleaving process by avoiding packet loss. Convolution codes are less complex and are used to provide error free transmission. The enhancement of energy efficiency is done using the convolution coded IFDMA. The chosen energy efficient architecture must be more power efficient and support high data rates, which is the main requirement for the mobile user. The proposed reliable and energy efficient architecture for LTE uplink system is implemented using Xilinx system generator tool.

Recently, there has been a tremendous increase in mobile data usage with widespread proliferation of smartphone like devices and increasing popularity of video streaming services such as YouTube. This is already causing overloading of 3G cellular access networks. It is estimated that even the 4G LTE (Long Term Evolution) technology which has significantly higher spectral efficiency than 3G will also face overloading in near future. As a result, it has become important to find out ways and means of offloading the traffic from the LTE network. One possible solution is offloading it to Wi-Fi to gain extra capacity and improve overall network performance. In this paper we have considered an outdoor macro cell LTE Network being offloaded by a Wi-Fi network. We study the loading of LTE Network in different types of user and traffic distribution and investigate how offload to Wi-Fi APs can help in easing the congestion in LTE network and thereby lead to better per user throughputs and better quality of experience to end users using NS-3. Also, among the various scheduling algorithms that have been defined for efficient resource allocation in LTE, three schedulers have been considered: Round Robin (RR), Proportional Fair (PF) and Priority Set Scheduler (PSS) schedulers and their performance has been evaluated in the offloading scenario.

In this paper, we investigate the performance of an alternative received signal filtering technique based on local averaging to improve the quality of handover decisions in Long Term Evolution (LTE) networks. The focus of LTE-Advance (LTE-A) networks is to provide enhanced capacity and reliability of radio access as well as broadband demand for mobile users. The necessity to maintain quality of service, especially for the delay sensitive data services and applications, has made mobility and handover decisions between the base stations in the LTE networks critical. Unfortunately, several handover decision algorithms in the LTE networks are based on the Reference Signal Received Power (RSRP) obtained as a linear averaging over the reference signals. The critical challenge with the linear averaging technique is that the limited reference signal available in the downlink packet introduces an estimation error. This estimation error is a result of the effects of linear averaging on propagation loss components in eliminating fast-fading from the received signals. Moreover, prompt and precise handover decisions cannot be based on inaccurate measurement. The standardized LTE layer 3 filtering technique is applied to the local averaged layer 1 signal to render it suitable for LTE handover decisions. The local averaging technique produces better handover than the linear averaging technique in terms of the reduced number of handover failures, improved high spectral efficiency and increased throughput, especially for cell-edge users with high speeds. The findings of this study suggest that the local averaging technique enhances mobility performance of LTE-Advance networks.

Wireless sensors may be connected directly to a cellular network. The power consumption and cost of these cellular devices need to be minimised. Sensors typically create small infrequent datagrams. A 3GPP Long Term Evolution (LTE) network needs to communicate many signalling messages in order to transfer these datagrams. This paper presents some novel techniques to reduce the power consumption and cost of LTE devices and to reduce the signalling associated with supporting sensor systems over an LTE network. (5 pages)

Mobile networks are expected to serve a wide range of verticals, however the Long Term Evolution (LTE) network is optimized for basic mobile operator services only. The network functions serving LTE networks are largely implemented as dedicated single function devices that offer poor customization options. This intrinsic inflexibility makes current LTE networks unable to meet the requirements of future mobile networks. For example, LTE networks experience signaling storms because the signals exchanged by the network functions cannot be optimized according to the current usage pattern of mobile services. Modularizing these network functions would enable a refactoring of the LTE network, allowing operators to compose networks that adapt and evolve with the influx of verticals. In this article, we present a new approach for refactoring the network functions serving LTE networks which can be leveraged to compose a modular mobile network optimized for the verticals using its services. As an example, we demonstrate that deploying network functions at the edge significantly reduces the signals exchanged within a mobile network.

This paper focuses on performance evaluation of the Train to Ground traffic exchanges used to ensure safety and monitoring train functionalities carried by the Train Control Management System (TCMS). In the framework of the European project Safe4Rail from the Shift2Rail program, we try to use LTE (Long Term Evolution) network as an alternative communication technology, instead of GSM-R (Global System for Mobile communications-Railway) because of some capacity and capability limits. First step, a pure simulation is used to evaluate the network load for a high-speed scenario, when the LTE network is shared between the train and different passengers. The simulation is based on the discrete-events network simulator Riverbed Modeler. Next, second step focusses on a co-simulation testbed, to evaluate performances with real traffic based on Hardware-In-The-Loop and OpenAirInterface modules. Preliminary simulation and co-simulation results show that LTE provides good performance for the TCMS traffic exchange in terms of packet delay and data integrity.

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The dense deployment of Femtocells within the Macrocell's coverage is expected to dominate the future of Long Term Evolution (LTE) networks. While Mobile Femtocells (Mobile-Femtos) could be the solution for vehicular networks when there is a need to improve the vehicular User Equipment (UE) performance by mitigating the impact of penetration loss and path-loss issues. The deployed Femtocells have operated in a co-channel deployment due to the scarcity of spectrums. This issue causes interference between Femtocells and Macrocells as well it causes extra overhead on the LTE networks because of the co-tire interference between adjacent Femtocells. In this paper two interference scenarios are considered, the interference between Mobile-Femto and Macrocell, and the interference between the Mobile Femtos themselves. Therefore, to avoid the generated interference between Femtocells, the controlled transmission powers as well as the coverage planning techniques have been discussed. While in the worst-case scenarios, a frequency reuse scheme has been proposed to avoid the generated interference effectively and dynamically between the Mobile-Femtos as well as their UEs and between the Macrocell UEs.

QoS-priority based load balancing algorithm for LTE systems with mixed users

Scalable priority-based resource allocation scheme for M2M communication in LTE/LTE-A network

In this article, the results of the development of a mathematical model for the time-frequency resource allocation of the uplink channel and flow service in LTE (Long Term Evolution) networks are given. The proposed model is aimed at ensuring the maximum performance of the radio channel and the guaranteed quality of service for data flows of wireless network users. A comparative analysis of the proposed model with the existing methods of the time-frequency resource allocation of the LTE technology is carried out in terms of ensuring the overall performance of the uplink and allocating the required transmission rate to user stations while maintaining the quality of service. It is shown that the proposed model of dynamic distribution of radio resources and servicing of data streams increases the overall performance of the uplink compared to the Round Robin and Proportional Fair methods, by 1.42 and 1.23 times, respectively.