The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper addresses the power assignment problem in multicarrier code-division multiple-access (MC-CDMA) systems. The problem is formulated as finding the correct transmission power to achieve a desired quality of service (QoS), described by an objective signal-to-interference and noise ratio (SINR). First, the model of the MC-CDMA is described, and by considering a matched filter at the receiver,...
In this work, the distributed power allocation problem in universal mobile telecommunication systems (UMTS) is studied under feedback signal-to-noise ratio (SNR) constraints. The sources of uncertainty are assumed to come from the quantization process and measurement noise in the closed-loop system. The power allocation problem is formulated as a reference tracking problem of a pre-defined signal...
This work studies the power control algorithm proposed by Foschini-Miljanic (1993), standardized for universal mobile telecommunication systems (UMTS). Continuous and discrete time versions of this algorithm are analyzed. First, it is shown that the distributed power allocation scheme can be visualized as a tracking problem of an equivalent power reference that specifies the desired quality-of-service...
In this paper we propose a power control policy over an imperfect fading channel within a cognitive spectrum sharing area. In particular, our proposed scheme maximizes the secondary user effective capacity subject to the average interference power and the secondary user transmit power constraints. We also investigate the minimization of average interference power at the Primary Receiver (PR) under...
The relay technology is an essential piece of LTE-Advanced in its pursuit of cost effective capacity enhancement and coverage extension. Simple RF repeaters have been widely used in cellular technologies to offer coverage extension. However, they cannot distinguish desired signals from interference and noise and are unable to operate with sophisticated mechanisms, such as power control, beam-forming,...
In a wireless communication network different users share a common resource. An objective of radio resource management is to assign the resources in an effective way between the users. Power control is an important component in this setting that has been extensively studied over the last two decades. In many real networks there are inherent time delays due to filtering of signals and control signaling...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
In this paper, we investigate the effect of interference on the performance of IEEE 802.11g wireless networks. We study different network configurations and evaluate their corresponding throughput performances with the aid of the ns2 simulator. We also provide recommendations for network deployment in order to minimize interference and improve the quality of service.
Power control is one of the major parts of cellular communication system. The power control helps maintain quality of service of the communication link. In this paper, a simple proportional integral (PI) control is used in the Code Division Multiple Access (CDMA) radio system to maintain the signal to noise ratio (SNR) around a desired level under channel fading environment with multiple access interference...
Medium access control (MAC) represents a vital part of any wireless network and directly affects important quality-of-service (QoS) measures such as the end-to-end delay or data throughput. In this study, we evaluate the delay performance and robustness of a distributed adaptive MAC scheme for power-controlled wireless networks with shared communication channels. The scheme was proposed in our previous...
Quality of service (QoS) guarantees grant ways for service providers to establish service differentiation among subscribers. On the other hand, service subscribers are also assured the level of service they paid for. In addition, the efficient level of service quality can be selected according to the subscribers' needs thus ensuring efficient use of available bandwidth. While network utility optimization...
This paper presents a decentralised cross-layer dynamic power control (DDPC) scheme for wireless mesh networks (WMNs). A general cross-layer occupation measure (COM) based on transmission scheduling probability (TSP) and power control policy (PCP) model is proposed. Depending on the network traffic application and multiple transmission activity (MTA), each user adjusts its power dynamically so as...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
This paper explores the attributes, layering models and objective functions in cross layer designs for mobile ad hoc wireless networks by taking all the statistical characteristics and constraints from the physical (PHY) layer, media access control (MAC) layer and network (NET) layer into consideration. This paper reviews the entire network optimization across all the PHY/MAC/NET layers. At the PHY...
The next generation of wireless networks (4G) will use OFDMA (Orthogonal Frequency Division Multiple Access) in the reverse link. In OFDMA, the reverse link resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers. Since at most one user is assigned to each of these tiles then reverse link transmissions within a sector are orthogonal. However, the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.