Posts

[MU-MIMO] Feedback reduction by multiuser diversity

We describe the throughput performance of user scheduling system when multiuser diversity is applied to the network.   If the number of scheduling users is K in the user scheduling network, the required feedback bits is reduced from B to B – log2 K where B is the number of feedback bits and K is the number of active users in the network.   The channel model of the uplink multiuser MIMO system is given by   y_k = H_k * x_k + n_k   where H_k is the wireless fading  channel vector for user k, x_k is the scalar transmit signal, and n_k is the noise signal vector.

Wireless System Modeling

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Noise modeling n 1 , ..., n NK are independent complex Gaussian noise terms with unit variance. Fading Modeling We consider a block fading channel with iid Rayleigh fading from block to block. The channel coefficients are iid complex Gaussian with unit variance.

Roadmap for real Globalization

We should know that in the near future, words can be replaced by multimedia for the major communication tool.

Wireless Story

This blog talks also about an wireless story. I am now preparing one technical paper to submit to an international conference and a journal, subsequently.

Cure a Headache - wikiHow

Cure a Headache - wikiHow

Openoffice weblog editing

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I'm now starting to use openoffice as a weblog editor. It is hard to edit the documents in weblog directly. I want to publish interesting scientific stories in the Internet. I have the biggest problem to upload my story in the Internet. The problem is my capability of English writing. I think my English is not that bad but at the same time, not that good. However, by recent long run practice, I can now edit the document in English as much as the native can understand it.

Complexity Mobile Networking

If we allow full mobile ad-hoc networking without any coordination, the interference among different mobiles will be serious. Then, almost nobody can communicate with any other terminals. The current wireless communication systems are coordinated by the centralized access pointer to avoid interuser signal interference. The access pointer makes the signals transmitted by the different mobiles orthogonal to each other so as not to generate interuser interference. We predict that the future mobile neetworking systems will not have a heavy network coordinator. When there is no coordinator, one possible solution to avoid the interference is to use beamforming arrays at terminals where beamforming can effectively suppress transmit and receive interference. For accurate beamforming with high perforamnce interference suppressing requires many antennas which are not practical in real situation because many antennas increase the installation cost such as RF price and device size limitation.