Digital Communications (Harada Lab)

Wireless Communication Technologies for Ubiquitous Networks

Academic Staff

Hiroshi HARADA

Hiroshi HARADAProfessor (Graduate School of Informatics)

Research Interests


TEL: +81-75-753-5317
FAX: +81-75-753-4982
E-mail: hiroshi.harada @

Hidekazu MURATA

Hidekazu MURATAAssociate Professor (Graduate School of Informatics)

Research Interests

  • Signal processing
  • Wireless communication systems
  • Multi-hop radio networks


E-mail: murata @


Keiichi MIZUTANIAssistant Professor (Graduate School of Informatics)

Research Interests


TEL: +81-75-753-5318
FAX: +81-75-753-4982
E-mail: mizutani @

Introduction to R&D Topics

Development of Wireless Distributed Networks with Coherent CoMP

[Equipment for wireless communication]

Multi-hop Radio Networks

By using multi-hop transmission, signals are forwarded from a source to its intended destination, which can be relatively distant. By changing single-hop transmission to multi-hop transmission, the distance per link can be reduced and the received signal power will increase. For this reason, the frequency reuse distance becomes shorter. As a result, the introduction of multi-hop transmission can improve the capacity of radio networks.

However in multi-hop radio networks, channel selection schemes designed for single-hop radio networks might not necessarily achieve high system throughput because the link with the lowest throughput limits the end-to-end throughput of a given multi-hop route. Through this research, these problems are clarified and solved by using a new algorithm.

[Example of channel selection in multi-hop radio networks]

Each color represents the index of the channel. Channels are spatially reused.