LTE Optimization and Resource Management in Wireless Heterogeneous Networks

Mobile communication technology is evolving with a great pace. The development of the Long Term Evolution (LTE) mobile system by 3GPP is one of the milestones in this direction. This work highlights a few areas in the LTE radio access network where the proposed innovative mechanisms can substantially improve overall LTE system performance. In order to further extend the capacity of LTE networks, an integration with the non-3GPP networks (e.g., WLAN, WiMAX etc.) is also proposed in this work. Moreover, it is discussed how bandwidth resources should be managed in such heterogeneous networks. The work has purposed a comprehensive system architecture as an overlay of the 3GPP defined SAE architecture, effective resource management mechanisms as well as a Linear Programming based analytical solution for the optimal network resource allocation problem. In addition, alternative computationally efficient heuristic based algorithms have also been designed to achieve near-optimal performance

A comprehensive simulation analysis of LTE Discontinuous Reception (DRX)

In an LTE cell, Discontinuous Reception (DRX) allows the central base station to configure User Equipments for periodic wake/sleep cycles, so as to save energy. DRX operations depend on several parameters, which can be tuned to achieve optimal performance with different traffic profiles (i.e., CBR vs. bursty, periodic vs. sporadic, etc.). This work investigates how to configure these parameters and explores the trade-off between power saving, on one side, and per-user QoS, on the other. Unlike previous work, chiefly based on analytical models neglecting key aspects of LTE, our evaluation is carried out via simulation. We use a fully-fledged packet simulator, which includes models of all the protocol stack, the applications and the relevant QoS metrics, and employ factorial analysis to assess the impact of the many simulation factors in a statistically rigorous way. This allows us to analyze a wider spectrum of scenarios, assessing the interplay of the LTE mechanisms and DRX, and to derive configuration guidelines

QoE-driven LTE Downlink Scheduling for Multimedia Services

The significant growth in multimedia services and traffic (e.g. VoIP, video streaming and video gaming) in current and emerging mobile networks including the latest 4G Long-Term Evolution (LTE) networks and the rising user expectation for high Quality of Experience (QoE) for these services have posed real challenges to network operators and service providers. One of the key challenges is how to bring multimedia services to the end-user over resource-constrained mobile networks with a satisfactory QoE. Cost-effective solutions are needed for network operators to improve the bandwidth usage of these mobile networks. Therefore, scheduling schemes are of extreme importance in LTE, where scheduling algorithms are responsible for the overall efficiency of resource allocation in an LTE system. The aim of the project is to develop novel QoE-driven scheduling algorithms for improving system capacity in delivering multimedia services over downlink 3GPP LTE. This is to move away from traditional QoS-driven scheduling schemes to a QoE-driven scheme which guarantee end-user satisfaction in resource allocation. The main contributions of the thesis are threefold: 1. Performance of several existing scheduling algorithms for VoIP applications was evaluated thoroughly in terms of QoE metric (i.e. MOS), instead of QoS metrics (e.g. packet loss and delay). Using QoE metrics instead of QoS ones will facilitate the development of QoE-driven scheduling schemes in order to achieve optimised end-user experiences or optimised mobile system capacity. 2. A novel QoE-driven LTE downlink scheduling scheme for VoIP application was developed to maximize the number of users per cell at an acceptable MOS score. The proposed scheme achieved significant improvement in cell capacity at an acceptable quality (75% compared to MLWDF, and 250% compared to PF and EXP-PF in all three lower speed scenarios considered). 3. A QoE-driven LTE downlink scheduling scheme for multiservice multimedia applications was developed to improve the cell capacity with satisfactory QoE for both VoIP and video streaming services. The proposed algorithm performed well in a pedestrian scenario increasing cell capacity to double for video stream with ‘Rapid Movement’ (RM) content. For ‘Medium Movement’ (MM) video content, the capacity was increased about 20% compared to MLWDF and by 40% compared to EXP-PF. In a vehicular scenario, the proposed scheme managed to enhance the cell capacity for MM video stream case. The project has led to three publications (IEEE Globecom’12 – QoEMC Workshop, IEEE CCNC’15 and IEEE MMTC E-letter/May-2015). A journal paper is in preparation.The Public Authority for Applied Education and Training , Kuwai

A Review of MAC Scheduling Algorithms in LTE System

The recent wireless communication networks rely on the new technology named Long Term Evolution (LTE) to offer high data rate real-time (RT) traffic with better Quality of Service (QoS) for the increasing demand of customer requirement. LTE provide low latency for real-time services with high throughput, with the help of two-level packet retransmission. Hybrid Automatic Repeat Request (HARQ) retransmission at the Medium Access Control (MAC) layer of LTE networks achieves error-free data transmission. The performance of the LTE networks mainly depends on how effectively this HARQ adopted in the latest communication standard, Universal Mobile Telecommunication System (UMTS). The major challenge in LTE is to balance QoS and fairness among the users. Hence, it is very essential to design a down link scheduling scheme to get the expected service quality to the customers and to utilize the system resources efficiently. This paper provides a comprehensive literature review of LTE MAC layer and six types of QoS/Channel-aware downlink scheduling algorithms designed for this purpose. The contributions of this paper are to identify the gap of knowledge in the downlink scheduling procedure and to point out the future research direction. Based on the comparative study of algorithms taken for the review, this paper is concluded that the EXP Rule scheduler is most suited for LTE networks due to its characteristics of less Packet Loss Ratio (PLR), less Packet Delay (PD), high throughput, fairness and spectral efficiency

Συγκριτική μελέτη της προσφερόμενης Ποιότητας Εμπειρίας αλγορίθμων ραδιο-χρονοπρογραμματισμού σε δίκτυα LTE

Στα δίκτυα LTE δίνεται μεγάλη έμφαση στην έννοια του QoE, μια παράμετρος υποκειμενική καθώς εκφράζει την εμπειρία του χρήστη συνολικά από την υπηρεσία του και δεν μπορεί να μετρηθεί με τις παραδοσιακές μετρικές της ποιότητας υπηρεσίας. Σκοπός της παρούσας εργασίας ήταν η μελέτη της προσφερόμενης Ποιότητας Εμπειρίας αλγορίθμων ράδιο-χρονοπρογραμματισμού σε δίκτυα LTE. Αρχικά γίνεται μια σύντομη αναφορά σε βασικές έννοιες των LTE δικτύων ιδιαίτερα σε αυτές που σχετίζονται με την λειτουργία του δικτύου για την εξασφάλιση της αναμενόμενης ποιότητας στο χρήστη. Στη συνέχεια περιγράφεται η διαδικασία του χρονοπρογραμματισμού και των παραμέτρων που λαμβάνει υπόψιν για τον διαμοιρασμό των πόρων. Αναλύονται αλγόριθμοι χρονοπρογραμματισμού που είναι διαθέσιμοι στη βιβλιογραφία. Οι αλγόριθμοι αυτοί χωρίζονται σε δύο μεγάλες κατηγορίες αυτοί που λαμβάνουν υπόψιν την ποιότητα του καναλιού και αυτοί που είναι ανεξάρτητοι. Γίνεται αναφορά και περιγραφή αλγορίθμων και από τις δύο κατηγορίες για να αποκτηθεί μια πιο σφαιρική άποψη για τον τρόπο λειτουργίας τους και τους στόχους που έχουν οι κατασκευαστές τους σε κάθε περίπτωση. Στη συνέχεια, στα πλαίσια της εργασίας αυτής πραγματοποιήθηκαν προσομοιώσεις με την χρήση του Vienna LTE Simulator για τον οποίο γίνεται μια περιγραφή. Επιπλέον παρουσιάζονται τα μοντέλα που χρησιμοποιήθηκαν για υπολογισμό του QoE. Τέλος για την εξαγωγή αποτελεσμάτων πραγματοποιήθηκαν προσομοιώσεις εξετάζοντας την εμπειρία του χρήστη σε υπηρεσίες Video, VoIP και FTP από την χρήση βασικών αλγορίθμων χρονοπρογραμματισμού, και συγκεκριμένα των Round Robin, Best CQI, Max TP και Alpha FairIn LTE networks, great emphasis is placed on the Quality of Experience (QoE), a parameter which is subjective, since the overall experience of the user is expressed and it can’t be measured with traditional quality of service metrics. In this dissertation radio scheduling algorithms for the provided Quality of Experience of LTE networks are examined. At first, there is a short reference to fundamental notions of LTE networks, especially for these that are related to the network operation and ensure the expected quality for the user. Then the scheduling procedure is described as well as the parameters that are taken into account for the allocation of the resources. Scheduling algorithms that are available, are being analyzed. The algorithms fit into two categories, those that take into account the channel quality and those that are independent. Reference and analysis is made for algorithms from both categories for a wider perception of the way they work and additionally the aims of their developers in each case are made clear. The Vienna LTE Simulator is thoroughly described and simulations have been performed. Additionally, the models used for the calculation of the QoE are presented. Finally, simulations have been performed, examining the user’s experience in Video, VoIP and FTP services using the basic scheduling algorithms, Round Robin, Best CQI, Max TP and Alpha Fair, and results and conclusions are described