Search

The exponential increase of global mobile data traffic requires future 5G system. Millimeter Waveform (mmWave) band is being considered as a candidate for new radio bands for 5G systems. In this paper, we present beam-forming technology on patch antenna array to cope path loss of mmWave band. In order to reduce the interference between beams and to compensate for this problems of limitation of user number, we proposed beam group method and GMPS(Group based MultiLevel Packet Scheduling) in 5G system based multi-beam. This paper evaluates performance of the GMPS in beam-forming system through the system level simulation.

Millimeter wave technology is major candidate technology for 5G network. Because of the high path loss characteristics of the mmWave system, beamforming technique is necessary to overcome this high path loss. Beamforming technology cannot achieve perfect beam alignment and it leads to degradation of the channel gain between the transceiver. Thus, we examine a gain degradation effect due to beam misalignment on mmWave beamforming system. We generated the channel coefficients by using QuaDRiGa channel model implementation. The channel gain analysis results shows that the misalignment of the BS beam causes high channel gain degradation.

To meet avalanche of traffic volume, the mmWave band in the 30-300GHz range is being considered as a candidate for new radio bands for 5G mobile communication systems. ETRI is developing mmWave based 5G mobile communication system in the Giga KOREA 5G (GK-5G) project. This paper introduces overview and features of the GK-5G mobile communication system and evaluates system coverage of the GK-5G mobile communication system through the system level simulation considering real geospatial information.

With increasing demand on location estimation, Bayesian tracking algorithm for mobile devices that requires low computing power is needed. By nonlinear/non-Gaussian Bayesian methods, grid-based methods are considered inefficient compared with the particle filters. We propose fast grid-based Markov localization algorithm by reducing the computational complexity of grid-based method. The fusion of dead reckoning and GPS location simulation shows that fast grid-based algorithm shows better performance on both location accuracy and time requirement.

Existing positioning systems such as global positioning system (GPS) or WiFi positioning system (WPS) are limited mainly to outdoor applications or are of poor accuracy without associated maps. Indoor work environment where one spend most of the time and wide adoption of smartphones with numerous embedded sensors provide new opportunities for researches on indoor user positioning. In this paper, we present an indoor positioning scheme using recently introduced smartphones equipped with sensors such as accelerometer, magnetometer, and gyroscope. We propose a practical indoor positioning method to handle complicated human movements and noisy inertial sensors in smartphones. We focus on providing indoor locations with accuracy by applying improved heading estimation solution. The key concept is to reduce errors caused by directional change since the critical component of positioning system is a heading orientation. We have simply used iPhone 4S for experiments and validated its practical usage in indoor environments. The extensive experimental results show that our system is needily applicable as a fundamental system for various mobile services on smartphones providing 2.42 times accuracy over than traditional methods on the average.

This paper reviewed brief transition of TV services and new challenge from existing TV service domains. We reviewed different service roles for each TV service domains, as well common direction and goals. Recently, new types of TV service are emerging, for example, IPTV from network providers, more competitive portal TV from content providers and advanced TV terminal from TV manufacturers. Also, we suggest a seamless TV service scenario between TV domain and mobile domain, which demands several service requirements to provide such kind of seamless TV service in current vertical TV environments. From this example, we focused on existing relevant standardization requirements from W3C and ITU-T. As well, further requirements are considered for harmonization of current standards.

In this paper, we propose a programmable string matching architecture to process multiple characters at a single cycle. To simplify the architecture of the previous works, we employ a method of realigning the input data stream by offsets. We show that some registers can be eliminated by using the method. Additionally, we present two different approaches to implement a programmable hardware for string matching on FPGA. We show the synthesis results for these two approaches.

Cognitive radio and femtocells are recent technology breakthroughs that aim at achieving throughput improvement by means of spectrum management and interference mitigation, respectively. However, these technologies are limited by the former's susceptibility to interference and the latter's dependence on bandwidth availability. In this paper, we overcome these limitations by integrating cognitive radio and femtocell technology and explore the byproduct's feasibility and throughput improvement. To realize this, we propose an integrated architecture and optimization framework based on power control, coverage assignment, and compensation schemes. Based on numerical results, the optimization framework is found to be both stable and converging. Simulation studies further show that the proposed architecture and optimization framework improves the aggregate throughput as the client population rises, hence confirming the successful and beneficial integration of these technologies.

Broadband wireless access network based on the IEEE 802.16e is one of the most promising solutions to provide broadband services. This paper proposes an efficient bandwidth request scheme for non real-time polling service and best effort service. In order to reduce the delay for bandwidth request, the proposed scheme makes BR code indicate the UIUC and the number of subchannels required by mobile station. Accordingly, it can omit the transmission procedure of bandwidth request message. We perform the mathematical analysis. The results show that the proposed scheme can reduce the delay and the signaling overhead compared to the IEEE 802.16e scheme.

In this paper, we propose keep-alive algorithm based periodic ranging code group (PRCG), in which the periodic ranging code is divided into groups and the AP (access point) performs this algorithm when the periodic ranging code arrives at AP in WiBro (wireless broadband Internet) system. In order to increase the radio bandwidth resource efficiency in this system, we propose keep-alive algorithm for finding abnormal AT (access terminal). From the numerical results, our proposed PRCG algorithm can support more radio resource efficiency compared to message-driven keep-alive algorithm.

This paper describes an anti-jamming algorithm in DS-CDMA cellular system. The proposed algorithm consists of detection, verification and control module. The detection module is based on the investigation of user's Eb/No received at the channel element (CE) of Base Station (BS) for finding jamming MS when all the SNRs of the mobile stations are greater than the threshold SNR. The verification module verifies whether the MS is jamming MS or not. The control module is based on the disconnection of the active call of jamming MS. Therefore, we can prevent the cell coverage from shrinking due to jamming MS. As a result, we can locate the jamming MS using the proposed anti-jamming algorithm in a CDMA cellular system and prevent the cell coverage from shrinking due to the jamming MS and decrease the load of system by hand-off.

The traffic control model based wireless ATM network which has a high speed and a broad range of quality of service (QoS) is used to support wireless multimedia services such as voice, video, and data file. One critical reason for applying ATM technology to a wireless multimedia network is that it has wireless environments that are different from the conventional wired ATM network such as error control, QoS control, and various data control. The system requirements to deploy the traffic control function in a wireless multimedia network are discussed. Also, we propose and establish the traffic control model to handle an integrated wireless multimedia traffic. Finally we analyzed an ATM cell structure to realize traffic control functions and reduce the error during transmission over the air interface.