Koichi Adachi

• Institute for Infocomm Research

In this letter, we propose a distributed resource reservation strategy for handover failure (HOF) reduction. The network status information that is locally available at each cell is utilized to reserve handover protection (HOP) resources in a dynamic and distributed manner. Each cell transmits downlink traffic using only the reserved HOP resources....

In this paper, we will first motivate the heterogeneous network as an evolutionary path to the fifth generation (5G) communications. We then present an agile software defined heterogeneous network architecture which virtualizes the various radio access networks such as cellular basestations and Wi-Fi access points and the various carrier frequencie...

The 14th IEEE International Conference on Communication Systems (ICCS 2014) was successfully held in Macau, China, from 19???21 November 2014. It was co-organized by the IEEE Communications Society Singapore Chapter, the IEEE Vehicular Technology Society Singapore Chapter, and the IEEE Singapore Section, and technically co-sponsored by the IEEE Com...

In this paper, we provide a survey on techniques to improve the spectrum and energy efficiency of wireless communication systems. Recognizing the fact that power amplifier (PA) is one of the most critical components in wireless communication systems and consumes a significant fraction of the total energy, we take a bottom-up approach to focus on PA...

We propose a time slot based transmission strategy, referred to as adaptive coordinated napping (CoNap), for energy saving in cellular networks under time-varying traffic demand. In adaptive CoNap network, multiple neighboring base stations (BSs) form a cluster and each BS operates in either a transmit mode (TM) or a nap mode (NM) in each time slot...

Power minimization of a cooperative decode-and-forward (DF) half-duplex relaying is considered in this paper. In the system considered, two source nodes (S) try to communicate with one destination (D). Recognizing the difference in link qualities, one of source nodes not only transmits its own information to D but also acts as a relay for the other...

In this paper, we consider a two-phase cooperative relay transmission setup with relay's private information (CRT- RPI). A half-duplex decode-and-forward (DF) relay not only helps the source-to-destination transmission, but also transmits its own private information mR to the destination. Distributed space-time coding is employed across the source...