Achievable rates and scaling laws for cognitive radio channels
EURASIP Journal on Wireless Communications and Networking - Cognitive Radio and Dynamic Spectrum Sharing Systems
Interference alignment and cancellation
Proceedings of the ACM SIGCOMM 2009 conference on Data communication
IEEE Transactions on Information Theory
IEEE Transactions on Information Theory
Interference alignment and the degrees of freedom of wireless X networks
IEEE Transactions on Information Theory
Parallel Gaussian interference channels are not always separable
IEEE Transactions on Information Theory
Degrees of freedom of the MIMO interference channel with cooperation and cognition
IEEE Transactions on Information Theory
A new achievable rate region for the discrete memoryless X channel
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4
A novel signaling for communication on MIMO Y channel: signal space alignment for network coding
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4
Achieving linear scaling with interference alignment
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
Relay-aided interference alignment for the quasi-static X channel
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
On the degrees of freedom of the 3-user Gaussian interference channel: the symmetric case
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
Interference alignment and the generalized degrees of freedom of the X channel
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
Outage efficient strategies for network MIMO with partial CSIT
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 1
Capacity enhancement of secondary links through spatial diversity in spectrum sharing
IEEE Transactions on Wireless Communications
Allerton'09 Proceedings of the 47th annual Allerton conference on Communication, control, and computing
3 user interference channel: degrees of freedom as a function of channel diversity
Allerton'09 Proceedings of the 47th annual Allerton conference on Communication, control, and computing
Interference alignment with asymmetric complex signaling
Allerton'09 Proceedings of the 47th annual Allerton conference on Communication, control, and computing
A robust interference alignment scheme for the MIMO X channel
APCC'09 Proceedings of the 15th Asia-Pacific conference on Communications
Adaptive multi-Tx multi-Rx MIMO transmission scheme for LTE-advanced downlink
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Diversity and multiplexing of opportunistic shared relay channel and the X-relay channel
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Degrees of freedom and sum rate maximization for two mutually interfering broadcast channels
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Degrees of freedom of the MIMO Y channel: signal space alignment for network coding
IEEE Transactions on Information Theory
WTS'10 Proceedings of the 9th conference on Wireless telecommunications symposium
Cognitive radios with multiple antennas exploiting spatial opportunities
IEEE Transactions on Signal Processing
IEEE Transactions on Information Theory
On feasibility of interference alignment in MIMO interference networks
IEEE Transactions on Signal Processing
Degrees of freedom of the K user M × N MIMO interference channel
IEEE Transactions on Information Theory
MSE-based transceiver designs for the MIMO interference channel
IEEE Transactions on Wireless Communications
Random access heterogeneous MIMO networks
Proceedings of the ACM SIGCOMM 2011 conference
Cognitive Radio MIMO Gaussian Broadcast Channels with the Power Constraint
Wireless Personal Communications: An International Journal
Hi-index | 755.32 |
We provide achievability as well as converse results for the degrees of freedom region of a multiple-input multiple-output (MIMO) X channel, i.e., a system with two transmitters, two receivers, each equipped with multiple antennas, where independent messages need to be conveyed over fixed channels from each transmitter to each receiver. The inner and outer bounds on the degrees of freedom region are tight whenever integer degrees of freedom are optimal for each message. With M = 1 antennas at each node, we find that the total (sum rate) degrees of freedom are bounded above and below as 1 les eta*x les 4/3. If M > 1 and channel matrices are nondegenerate then the precise degrees of freedom eta*x = (4/3)M. Thus, the MIMO X channel has noninteger degrees of freedom when M is not a multiple of 3. Simple zero forcing without dirty paper encoding or successive decoding, suffices to achieve the (4/3)M degrees of freedom. If the channels vary with time/frequency then the channel with single antennas (M = 1) at all nodes has exactly 4/3 degrees of freedom. The key idea for the achievability of the degrees of freedom is interference alignment-i.e., signal spaces are aligned at receivers where they constitute interference while they are separable at receivers where they are desired. We also explore the increase in degrees of freedom when some of the messages are made available to a transmitter or receiver in the manner of cognitive radio.