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We investigate enhanced downlink multiuser multiple input multiple output (MU-MIMO) transmission schemes for 3GPP LTE-Advanced based on system level simulations. As compared to Rel. 8 LTE single user MIMO (SU-MIMO), MU-MIMO has the potential to better exploit the spatial dimension of MIMO channels in some scenarios. Although Rel. 8 LTE defines a simple MU-MIMO mode, more advanced MU-MIMO techniques...
Coordinated Multi-Point (CoMP) transmission is considered in 3GPP LTE-Advanced as a key technique to improve the cell-edge performance. In order to support joint resource allocation among coordinate cells in CoMP systems, efficient frequency reuse schemes need to be designed. However, most of the existing frequency reuse schemes are not suitable for CoMP transmission due to not considering multi-cell...
In this paper, we evaluate the capacity gains expected when introducing HSUPA+ capable devices in the network. We first develop a flow level capacity for a cell carrying legacy UMTS devices in addition to HSPA and HSPA+ ones. We show how to calculate the QoS for both real time and elastic traffic using queuing theory analysis. Our model is next applied to assess the user-perceived QoS, i.e. the blocking...
We present a novel solution to the problem of handover between two different wireless technologies. We illustrate this solution with the example of LTE (Long Term Evolution) to CDMA (Code Division Multiple Access) handover. Current inter-technology handover can take approximately 6 to 7 seconds and hence can heavily impact the network performance. We assume that two receivers (primary and secondary)...
With widespread use of multimedia communication, quality of experience (QoE) progressively becomes an important factor in networking today. Besides, multimedia applications can be supported under various technologies, including wired and wireless networks. Among them, Universal Mobile Telecommunications System (UMTS) is one of the most popular technology thanks to its support on mobility. Improved...
In this paper we analyze the performance of a self optimizing algorithm for handover parameter control which adjusts the settings depending on the oscillations experienced between different cell pairs. We compare the algorithm performance with two different reference cases. The first one allowing the system to trigger handover as soon as the best perceived cell changes, with the users connected always...
3GPP Release 7 introduced several new powerful features to the existing HSDPA (High Speed Downlink Packet Access) functionality including higher order modulation (SIMO 64 QAM - Single Input Multiple Output, 64 Quadrature Amplitude Modulation) and MIMO 16QAM (Multiple Input Multiple Output). These additional features - commonly referred to as “HSPA+” - aim at improving user experience by increasing...
We compare the performance of the downlink of a 3GPP UTRAN Long Term Evolution (LTE) system with multi-user (MU) multiple input multiple output (MIMO) support and channel state information (CSI) feedback to a standard MU-MIMO LTE system utilizing channel quality indicator (CQI) feedback only. For the latter case, we propose an efficient method for estimating the appropriate MU-MIMO transmission parameters...
This paper discusses the use of high altitude platforms, HAPs, to provide mobile communication services to on-ground customers. The paper explains the behavior of UMTS radio network in a situation, where the service is being provided by HAP and terrestrial base stations in a disaster scenario. In the disaster scenario, a set of adjacent terrestrial cellular base stations in the middle of the network...
This paper evaluates the performance of two simple packet scheduling algorithms for real-time traffic in the third generation partnership project long term evolution (3GPP LTE) system. These algorithms, known as Algorithm 1 and Algorithm 2 for this paper, were proposed to support real-time traffic in orthogonal frequency division multiple access (OFDMA) system. Simulation results show that Algorithm...
In this paper, a low-complexity symbol detector is presented targeting the emerging 3GPP LTE and WiMAX standards. The detector is the VLSI implementation of a novel MIMO detection algorithm recently proposed. Compared to the design in the reference, the detector performs better while consumes less silicon area. Including a microcode controlled channel preprocessing unit and a pipelined detection unit,...
Dimensioning and planning air interface of the evolution of UMTS networks based on HSPA technique is interesting for mobile operators. This paper deals with coverage-limited and capacity-limited dimensioning of HSPA based Beyond 3G networks with the necessary analytical support. The models established for coverage-limited case are exploited to generate abacuses useful mainly for initial dimensioning...
This contribution provides insight into the performance of the currently deployed 3G cellular systems HSDPA and WiMAX. In extensive measurement campaigns we measured the physical layer throughput of these 3G systems in different environments (alpine and urban) and compare the results rigorously to their upper bounds derived from the well known Shannon capacity. By separating the observed losses into...
The system characteristics of time division duplex-long term evolution (TDD-LTE) system and different inter-cell interference coordination (ICIC) algorithms are analyzed. Dynamic TDD-LTE system level simulator based on OPNET software is established to investigate the system performances with and without the interference coordination algorithms. Simulation results indicate that adopting the interference...
In order to settle the conceal terminal, frequency shift, losing package, mistaking code problems of air-to-ground data link, which were aroused by high speed moving of node and more complicated network environment, two important MAC communication mechanism-the MSDU frames subsection and RTS/CTS handshake mechanism-were introduced. Then some simulation experiment were made from little operation and...
In this paper, we present a man-in-the-middle attack on 3G-WLAN internetworking, one of the widely used technologies in real-world deployment. Since 3G runs CS (Circuit Switch) in many practice and WLAN runs PS (Packet Switch), a gateway is necessary to perform protocol transforming to achieve internetworking of 3G and WLAN. However, the 3G-WLAN gateway is frangible to the kernel upgrade attack which...
On the MU-MIMO broadcast channel, Per-User Unitary and Rate Control (PU2RC) as a practical design is proposed for emerging cellular standards in 3GPP LTE. Unfortunately, when the number of users is small, the performance of PU2RC would be degraded with the increase of codebook size. In this paper, we propose an efficient user scheduling scheme to overcome this defect in PU2RC by enlargement of user...
Fractional Frequency Reuse (FFR) is one of the key concepts for enhancing cell-edge performance of OFDMA networks. Standard FFR allows one sub-band to be allocated for each cell. This limits the performance improvement of cell edge users, especially those bandwidth-sensitive users. With flexible sub-band allocation, cell edge can be allocated more than one sub-band, thereby performance can be improved...
Incorporating relay nodes in cellular networks, e.g. UMTS/ HSPA, is beneficial for extending coverage as well as for service enhancement. In this paper we study the inter-cell interference generated by a relay-enabled cell and how this influences the performance of mobile users. The performance measures of interest are the inter-cell interference distribution, realized rates and flow throughput. Our...
Apart from the number and types of applications available to users of diverse devices with various characteristics, a highly relevant issue in current and future wireless environment is the coexistence of multiple networks supported by various access technologies deployed by different operators. In this context, the aim is to keep the mobile users “always best connected” anywhere and anytime in such...
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