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This paper draws on a 2-week design workshop conducted at a rural primary school in northern India to provide recommendations on carrying out participatory design with school children in rural, underdeveloped regions. From our experiences in prototyping low-tech and hi-tech English language learning games with rural student participants, we advocate that researchers build a more equal relationship that is qualitatively different from one between teachers and students, enlist local adults and children as facilitators, and explore hi-tech prototyping to inspire the best designs.

phase difference is attributed to the unbalanced characteristics of the varactor diodes and 3-dB couplers. CONCLUSIONA novel and compact variable power divider based on 3-dB couplers and varactor diodes is proposed in this article. The variable power divider is initially studied using the even-and odd-mode techniques. Then, based, on the obtained equations a variable power divider operating in the frequency range 2.3-2.7 GHz was fabricated and measured. The measured results reveal that the proposed structure offers a dynamic range of minimum 6 dB, whereas the reflection losses are greater than À13 dB, regardless of the dc bias conditions. It is, however, believed that the dynamic range can be extended by using balanced varactor diodes in the circuit of the reflective loads. The proposed structure is, particularly, suitable for the implementation in the circuit of a variable input power for the Doherty amplifier, due to its inherent 90 o and continuous input power distribution.

Abstract-An active interference cancellation scheme is presented to mitigate interference between Bluetooth and wireless local area network (IEEE 802.11 b) radios operating in close proximity. This method is extensible to other mutually interfering radio devices. A reference signal correlated to the original interferer is used to generate a cancellation signal by means of amplitude and phase alignment, and filtration. The filter employed emulates the coupling channel responsible for interference. An implementation of this procedure in 0.18-m Si-complementary metal-oxide-semiconductor (CMOS) integrated-circuit (IC) technology is also presented. The circuits fabricated are tunable and are controlled by a closed-loop adaptive process including an error minimization method. The cancellation system designed achieves 15-30 dB of interference suppression for different cases. A total power of 14 mW is dissipated by the CMOS ICs designed.

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