• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.280-292
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• 2014

Recently, heterogeneous networks consisting of small-cells on top of traditional macro-cellular network has attracted much attention, because traditional macro-cellular network is not suitable to support more demanding mobile data traffic due to its limitation of spatial reuse. However, due to the transmit power difference between macro- and small-cells, most users are associated with macro-cells rather than small-cells. To solve this problem, enhanced inter-cell interference coordination (eICIC) has been introduced. Particularly, in eICIC, the small-cell coverage is forcibly expanded to associate more users with small-cells. Then, to avoid cross-tier interference from macro-cells, these users are allowed to receive the data during almost blank subframe (ABS) in which macro-cells almost remain silent. However, this approach is not sufficient to balance the load between macro- and small-cells because it only expands the small-cell coverage. In this paper, we propose a load balance scheme improving proportional fairness for heterogeneous networks employing eICIC. In particular, the proposed scheme combines the greedy-based user association and the ABS rate determination in a recursive manner to perform the load balance.

• Journal of Korean Society of Forest Science
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• v.81 no.3
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• pp.263-272
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• 1992

In a torrential river, the flow of debris forms deposits in the river bed, which show the characteristics of the channel bed movement in the watershed. The annual rings of the trees, in the natural evenaged forests on the deposits, indicate when each deposit occurred. Based on the topographical and vegetational indicators on the sediment of Yongcheon and Yeounae rivers, the movement occurrence years were estimated. 1. The cross sectional shapes of deposits in torrential river are in tiers and even-aged forests tend to establish on each tier. 2. Generally the older the forest age is, the higher the height of step from the lowest base tend to become, which indicates discrete movement in magnitude and frequency. 3. The ages of trees indicate the year when deposition occurred, and so may be useful as plant indicator to get spatial-temporal information of deposits. 4. The deposits volumes(F. V.) were dependent on the age distribution of deposits in length, average width and average height. And the average width and the average height of deposits were increasing with the age.