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In this paper, we propose a hybrid forwarding scheme for cooperative relaying in orthogonal frequency division multiplexing (OFDM) based networks. The proposed hybrid forwarding scheme changes the type of the forwarding scheme used by a relay terminal on a per sub-carrier basis. It adaptively decides to use either "Amplify and Forward (AF)" or "Decode and Forward (DF)" or "no relay" according to the instantaneous Signal to Noise Ratio (SNR) conditions between the source, relay and destination terminals. This decision is made based on analytically derived equations, which makes it possible to take into account all the link conditions in a relay network with low computational complexity. The bit error performance is presented for cooperative receive diversity with AF, with DF, with proposed hybrid forwarding scheme and for noncooperative transmission. Our results show that the proposed hybrid forwarding scheme significantly outperforms conventional cooperative relaying with AF and DF, and direct transmission schemes.

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We propose a link adaptation and selection method for the links constituting an orthogonal frequency division multiplexing (OFDM) based wireless relay network. The proposed link adaptation and selection method selects the forwarding, modulation, and channel coding schemes providing the highest end-toend throughput and decides whether to use the relay or not. The link adaptation and selection is done for each sub-channel based on instantaneous signal to interference plus noise ratio (SINR) conditions in the source-to-destination, source-to-relay and relayto-destination links. The considered forwarding schemes are amplify and forward (AF) and simple adaptive decode and forward (DF). Efficient adaptive modulation and coding decision rules are provided for various relaying schemes. The proposed end-to-end link adaptation and selection method ensures that the end-to-end throughput is always larger than or equal to that of transmissions without relay and non-adaptive relayed transmissions. Our evaluations show that over the region where relaying improves the endto-end throughput, the DF scheme provides significant throughput gain over the AF scheme provided that the error propagation is avoided via error detection techniques. We provide a frame structure to enable the proposed link adaptation and selection method for orthogonal frequency division multiple access (OFDMA)-time division duplex relay networks based on the IEEE 802.16e standard.Index Terms: Adaptive modulation and coding (AMC), amplify and forward (AF), CRC, decode and forward (DF), orthogonal frequency division multiplexing (OFDM), relay, throughput.

The number of grandmothers who provide regular care for their grandchildren and do housework for their daughters or daughters-in-law is increasing in Turkey. While perpetuating traditional gender roles for themselves as a surrogate daughter, wife, or daughter-in-law, these women nonetheless enable younger women to distance themselves from obligatory care work at home. The sociocultural concepts of kinship ties, economic need, or love for grandchildren do not fully explain why grandmothers assume the role of caregiver for their grandchildren. Drawing on interviews with 25 grandmothers from middle-class families in urban Turkey, this article shows, first, that these women’s gendered subjectivity is formed by both habitual and intentional actions that defying the oppression and resistance duality within patriarchal Turkish society. Second, in dialogue with the scholarship on the “classic patriarchal bargain”1 and feminist analyses of neoliberal social policy, the article suggests that these grandmothers’ inarticulate desire to live in solidarity with the younger generation of women may be turned into a government instrument in the context of Turkey’s increasingly family-centered neoliberal social policy environment.

In June 2013, protests that erupted in Gezi Park in Istanbul, Turkey were met with state violence, mobilizing hundreds of native physicians to deliver emergency medical care. Drawing on ethnographic fieldwork in makeshift clinics during these protests, interviews with Gezi physicians and analyses of recent laws restricting emergency care provision, in this article I explore the criminalization of clinical practice through legal and coercive means of the government and the delegitimization of state violence through clinical and expert witnessing practices of physicians. As I show, material, legal, and discursive articulations of the idiom of medical neutrality revolve around the tension between medical praxis as neutrality and medical praxis as political participation. I offer a reconsideration of medical humanitarian and human rights regimes in terms of their consequences for inciting, documenting and restricting state violence.

Abstract. For the performance evaluation of future wireless communication systems, such as the fourth generation wireless networks, traffic traces of realistic services are needed. Multiple description coding (MDC) is gaining a lot of interest lately and is a viable solution to provide robust video services over single or multi hop wireless networks and MDC introduces more flexibility for network coding. Furthermore it has the capability to support heterogeneous terminals as they are accepted to be used in 4G wireless networks. By means of twelve well known video sequences, in different video formats, we generate the frame size traces and evaluate the multiple description coding characteristics. In addition to that we highlight the expected overhead due to the underlying RTP/UDP/IP protocol suite. As an objective quality measurement at the application layer, we investigate the video quality in dependency of lost and error-prone descriptors. This allows researcher to convert the network losses of their network models directly into video quality values. This step makes the work unique as single layer coded video streams would always need further postprocessing to retrieve the video quality.

Several trunked private mobile radio (PMR) systems have been designed over the last decade, most of which have symmetric downlink and uplink channel capacities. These systems may not be spectrally efficient in case of group or broadcast-based voice and data calls, a common feature of PMR systems. We propose a new asymmetric PMR system comprising a wideband OFDM-based downlink and a narrowband uplink, which not only achieves a better spectral efficiency but also can support high bit rate multimedia applications. The system is shown to have high trunking efficiency since all users are assumed to use the pool of channels available in the wideband downlink. In this paper, we study the performance and capacity of a private mobile radio system using a digital audio broadcasting (DAB) downlink. In particular, we study the efficiency of such a system for voice calls using voice activity detection and statistical multiplexing. Moreover, we show that, the efficiency of the system can significantly increase, if the incoming calls, which can not find an available channel, are allowed to wait a certain amount of time before occupying a channel. © 2003 IEEE