Downlink radio resource allocation for coordinated cellular OFDMA networks
Base station coordination is considered as a promising technique to mitigate inter-cell interference and improve the cell-edge performance in cellular orthogonal frequency division multiple-access (OFDMA) networks. The problem to design an efficient radio resource allocation scheme for coordinated cellular OFDMA networks incorporating base station coordination has been only partially investigated. In this contribution, a novel radio resource allocation algorithm with universal frequency reuse is proposed to support base station coordinated transmission. Firstly, with the assumption of global coordination between all base station sectors in the network, a coordinated subchannel assignment al…
The dialogical bricoleur? Expectations towards internet-based services in Norway and Sweden
Mental health is a multifaceted concept that has been described and understood differently throughout history. The emergence of internet-based services has signalled changes in both the delivery of ...
Psykisk helsearbeid på internett: konsekvenser for normalitets- og identitetsdannelse hos ungdom
Psykisk helsearbeid på internett øker i omfang, og verdsettes på grunn av bekvemmelighet, lave kostnader og muligheter for anonymitet. Artikkelen bygger på en kartlegging av norske og svenske nettbaserte eposttjenester for ungdom og unge voksne, og viser at det var 24 nettsteder som tilbød slike tjenester i 2009. Tjenestene hadde opphav i både offentlig og frivillig sektor. Flesteparten av sidene fra offentlig sektor tok utgangspunkt i eksisterende tjenestetilbud, og var en videreutvikling av tjenestene for å styrke tilgjengeligheten av psykisk helsetjenester. Andre sider oppsto som en konsekvens av FNs konvensjon av barns rettigheter. Størsteparten av sidene fra frivillig sektor ble utvikl…
Wireless energy and information transmission in FSO and RF-FSO links
We propose and analyze a wireless energy and information transmission scheme in free-space optical (FSO) links. The results are presented for both quasi-static and fast-fading conditions. We derive closed-form expressions for throughput, outage probability, and optimal power allocation optimizing the system throughput/outage probability. Finally, we complement the FSO link with an additional radio frequency (RF) link to create a hybrid RF-FSO system and reduce the system outage probability. The results show that joint implementation of the RF and FSO links leads to considerable performance improvement, compared to the cases with only FSO-based communication.
Resource allocation for OFDMA systems with multi-cell joint transmission
This paper considers the downlink resource allocation of a coordinated multi-cell cluster in OFDMA systems with universal frequency reuse. Multi-cell joint transmission is considered via zero-forcing precoding. Furthermore, joint optimization of the user selection and power allocation across multiple subchannels and multiple cells is studied. The objective is to maximize the weighted sum rate under per-base-station power constraints. Based on general duality theory, two iterative resource allocation algorithms are proposed and compared with the optimal solution, which requires an exhaustive search of all possible combinations of users over all subchannels. Simulation results show that the t…
Partial joint processing with efficient backhauling using particle swarm optimization
In cellular communication systems with frequency reuse factor of one, user terminals (UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount …
A novel frequency reuse scheme for coordinated multi-point transmission
La transmisión multipunto coordinada (CoMP) se considera en 3GPP LTE-Advanced como una técnica clave para mejorar el rendimiento en el borde de la célula. Con el fin de apoyar la asignación conjunta de asignación de recursos entre células coordinadas en sistemas CoMP, es necesario diseñar esquemas eficientes de reutilización de frecuencias. Sin embargo, la mayoría de los esquemas de reutilización de frecuencias existentes no son adecuados para transmisión CoMP debido a que no consideran el escenario de transmisión conjunta multicelular en su regla de reutilización de frecuencias. Para resolver este problema, en este trabajo se propone un esquema de reutilización de frecuencias que divide el…
Improved resource allocation strategy in SU-CoMP network
Coordinated multi-point transmission and reception (CoMP) for single user, named as SU-CoMP, is considered as an efficient approach to mitigate inter-cell interference in orthogonal frequency division multiple access (OFDMA) systems. Two prevalent approaches in SU-CoMP are coordinated scheduling (CS) and joint processing (JP). Although JP in SU-CoMP has been proved to achieve a great link performance improvement for the cell-edge user, efficient resource allocation (RA) on the system level is quite needed. However, so far limited work has been done considering JP, and most existing schemes achieved the improvement of cell-edge performance at cost of the cell-average performance degradation …
Internet-based Mental Health Services in Norway and Sweden: Characteristics and Consequences
Published version of an article in the journal: Administration and Policy in Mental Health and Mental Health Services Research. Also available from the publisher at: http://dx.doi.org/10.1007/s10488-011-0388-2 Internet-based mental health services increase rapidly. However, national surveys are incomplete and the consequences for such services are poorly discussed. This study describes characteristics of 60 Internet-based mental health services in Norway and Sweden and discusses their social consequences. More than half of the services were offered by voluntary organisations and targeted towards young people. Professionals answered service users’ questions in 60% of the services. Eight majo…
Multicell power allocation method based on game theory for inter-cell interference coordination
As a new technology, coordinated multipoint (CoMP) transmission is included in LTE-Advanced study item. Moreover, the network architecture in LTE-Advanced system is modified to take into account coordinated transmission. Under this background, a novel power allocation game model is established to mitigate inter-cell interference with cellular coordination. In the light of cellular cooperation relationship and centralized control in eNodeB, the power allocation in each served antenna unit aims to make signal to interference plus noise ratio (SINR) balanced among inter-cells. Through the proposed power allocation game algorithm, the users' SINR can reach the Nash equilibrium, making it feasib…
On the performance of joint processing schemes over the cluster area
En este trabajo se caracterizan tres esquemas de transmisión conjunta para el enlace descendente y se compara su rendimiento dentro de un clúster de estaciones base. La motivación de este estudio es analizar el rendimiento de estos esquemas dentro del área del clúster, como un primer paso hacia el diseño de un esquema de transmisión conjunta adaptable que soporte escenarios de uso dinámicos. Cada uno de los esquemas analizados, centralizado, parcial y distribuido, requiere una cantidad diferente de conocimiento del canal disponible en el lado del transmisor, un intercambio distinto de información entre estaciones base y la retroalimentación de los usuarios. Además, estos esquemas muestran d…
Reaching out to people struggling with their lives: a discourse analysis of answers from Internet-based services in Norway and Sweden
Anders Johan W Andersen,1 Tommy Svensson21Department of Psychosocial Health, University of Agder, Grimstad, Norway; 2Department of Behavioural Sciences and Learning, Linköping University, Linköping, SwedenAbstract: The Internet has enlarged the scope of human communication, opening new avenues for connecting with people who are struggling with their lives. This article presents a discourse analysis of 101 responses to 98 questions that were posted on 14 different Internet-based mental health services in Norway and Sweden. We aimed to examine and describe the dominant understandings and favored recommendations in the services’ answers, and we reflected upon the so…
Struggles for recognition: a content analysis of messages posted on the Internet
Anders Johan W Andersen,1,2 Tommy Svensson31Department of Psychosocial Health, University of Agder, Norway; 2Nordic School of Public Health, Gothenburg, Sweden; 3Department of Behavioral Sciences and Learning, Linköping University, Linköping, SwedenBackground: The Internet has enlarged the possibilities of human communication and opened new ways of exploring perceptions of mental health. This study is part of a research project aiming to explore, describe, and analyze different discourses of mental health in Norway and Sweden, using material from Internet-based services.Aim: To examine messages posed by users of publicly available question-and-answer services and to descri…
Resource allocation for clustered network MIMO OFDMA systems
In this article, we address the resource allocation problem for the downlink of a large network multiple input multiple output orthogonal frequency division multiplexing system with 3-sector base stations. The system is statically divided into a number of disjoint clusters of sectors. A two-step resource allocation scheme is proposed involving the inter-cluster and the intra-cluster levels. As a first step or inter-cluster level, two cooperative frequency reuse approaches are designed to mitigate the inter-cluster interference. A user partition method is proposed to divide the users of each cluster into cluster-edge and cluster-center users. To balance the cell-edge and the cell-average per…
Power allocation for two-cell two-user joint transmission
In this paper, we develop a power allocation scheme for the downlink of a two-cell two-user joint transmission system. The objective is to maximize the sum rate under per-cell power constraints. We study a worst case scenario where the carrier phases between the two base stations are un-synchronized, so that joint transmission must be performed without precoding. The derived power allocation scheme is remarkably simple, i.e., each cell transmits with full power to only one user. Note that joint transmission is still possible, when two cells select the same user for data transmission. Moreover, we prove that, in this scenario, the joint transmission case happens with higher probability when …