Jieying Chen

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In a downlink Orthogonal Frequency Division Multiple Access (OFDMA) system, optimally allocating sub-channels across mobile users can require excessive feedback of channel state information (CSI). We consider an OFDMA model in which the feedback overhead is explicitly taken into account, given a fixed feedback rate and finite coherence time. The tradeoff(More)
We consider allocation of sub-channels to users in a downlink OFDMA system. Each user feeds back one bit per sub-channel, which indicates whether or not the gain exceeds a threshold. Users are assigned priority weights, and the thresholds are selected to maximize the weighted sum capacity. We analyze the behavior of the optimal thresholds and growth in(More)
We consider the capacity of a downlink orthogonal frequency division multiple access (OFDMA) system with limited feedback rate R<sub>F</sub> per sub-channel and finite coherence time T. The feedback is used to relay channel state information (CSI) from K users to the base station. The order-optimal capacity growth with Rayleigh fading sub-channels is(More)
Heterogeneous cellular network (Hetnets), where various classes of low power base stations (BS) are underlaid in a macro-cellular network, is a promising technique for future green communications. These new types of BSs can achieve substantial improvement in spectrum-efficiency and energy-efficiency via cell splitting. However, mobile stations perceive(More)
We propose and analyze a limited feedback scheme for downlink MIMO-OFDMA. Our analysis explicitly accounts for the feedback overhead by assuming a time division duplex system in which all feedback and data transmission must occur with a coherence time. As the fraction of coherence time devoted to feedback increases, the base station can allocate resources(More)
For many problems of traditional technical services, this paper presented the networked technical services oriented the production process in order to meet the needs of modern manufacturing model. This paper focused on analyzing the user needs of production process technical services, and studied the main problems existing in the traditional mode of(More)
Cross-cultural research has traditionally emphasized predicting adjustment, treating it as a level to be achieved more than a change process to be understood and controlled. The lack of focus on process integration has inhibited our understanding of precisely why and how adjustment processes unfold and ultimately cause (dys)functional change in criteria. In(More)