Hironori Mizuguchi

Development of parallel type multi-stage interference canceller for W-CDMA

This paper describes a developed W-CDMA base station testbed with a practical multi-stage interference canceller, which is processed by high-speed digital signal processing cards. The multi-stage canceller features a parallel structure with a cancellation control factor, which can make the parallel cancelling operation stable. A laboratory experiment demonstrates that the developed interference canceller has a high cancelling capability and near-far resistance even when the interference (2 users) power is 9 dB higher than the desired user. The development and experiment proves that this multistage canceller is feasible and effective technology for W-CDMA performance enhancement.

Ranking Method of Object-Attribute-Evaluation Three-Tuples for Opinion Retrieval

In this paper, we propose a ranking method for opinion retrieval that uses a confidence model of opinion as a three-tuple of object-attribute-evaluation . The confidence model has two characteristics for calculating confidence scores. One, the model divides a three-tuple of an opinion into two pairs: object-attribute and attribute-evaluation. Two, the confidence model evaluates an opinion simultaneously using syntactic and semantic analyses. Our experiments show that our method improves the precision of the top fifty opinions in search results by ranking based on our confidence compared with random ranking.

Performance evaluation of CDMA adaptive interference canceller with RAKE structure using developed testbed in multiuser and multipath fading environment

We describe the implementation of the proposed single user type CDMA adaptive interference canceller (AIC) with RAKE structure in a base station testbed, and evaluate its performance in the multiuser and multipath fading environment. Laboratory experiments demonstrate that the AIC receiver is much more near-far resistant than a conventional matched filter (MF) receiver in the multiuser case. When the power of the other users is 6 dB larger than that of the desired user, the AIC receiver can achieve a BER of 10/sup -3/ at C/PG=33.3% (eight users) in the 2-path fading channel, while the MF receiver cannot achieve the BER at C/PG of more than 20.8% (five users), it can achieve the BER at C/PG=33.3% in the equal power case. Furthermore, we evaluate the effect of transmission power reduction in a mobile station with transmission power control (TPC). Experimental results show that the required transmission power can be greatly reduced by 3.0 dB and 9.2 dB with the AIC receiver at C/PG=29.2% (seven users) and 33.3% (eight users), respectively.

5w viewpoints associative topic search for networked conversation support system

To build up spontaneous conversation, it is important to select topics without a feeling of strangeness. When someone notices others are not interested in a topic, he/she tries to find a new topic. Then, he/she thinks of viewpoints of the conversation and selects a topic associated with the current topic from the viewpoints. To automate viewpoint-based topic selection, we present 5W viewpoint associative topic search. The method estimates the weights of 5W viewpoints (who, what, where, when and why) from conversation, to use an appropriate similarity to search for the next topic.