Abstract
We study a class of two-transmitter two-receiver dual-band Gaussian interference channels (GIC) which operates over the conventional microwave and the unconventional millimeter-wave (mm-wave) bands. This study is motivated by future 5G networks where additional spectrum in the mm-wave band complements transmission in the incumbent microwave band. The mm-wave band has a key modeling feature: due to severe path loss and relatively small wavelength, a transmitter must employ highly directional antenna arrays to reach its desired receiver. This feature causes the mm-wave channels to become highly directional, and thus can be used by a transmitter to transmit to its designated receiver or the other receiver. We consider two classes of such channels, where the underlying GIC in the microwave band has weak and strong interference, and obtain sufficient channel conditions under which the capacity is characterized. Moreover, we assess the impact of the additional mm-wave band spectrum on the performance, by characterizing the transmit power allocation for the direct and cross channels that maximizes the sum-rate of this dual-band channel. The solution reveals conditions under which different power allocations, such as allocating the power budget only to direct or only to cross channels, or sharing it among them, becomes optimal.
Highlights
Current technology such as 4G (e.g., [1]) is rapidly becoming inadequate to support the exponential growth in wireless traffic [2]
– If the channel parameters satisfy one of the following criteria, transmitting only in the direct channels is approximately optimal, in the sense that the difference between the sum-rates resulting from allocating to only direct channels and allocating optimally in all channels, is negligibly small: (a) the transmit powers in the underlying Gaussian interference channels (GIC) in the microwave band is very small; or (b) the cross channel gains in the mm-wave band are very large
In the Direct-and-Cross-Link IC (DCLIC), there are n channel uses in the first band, n1 cross channel uses in the second band, and n2 direct channels uses in the second band
Summary
Current technology such as 4G (e.g., [1]) is rapidly becoming inadequate to support the exponential growth in wireless traffic [2]. We consider two specific classes, the strong CLIC and the weak CLIC, where the underlying GIC in the microwave band has strong and weak interference, respectively, and characterize sufficient conditions on the channel parameters under which their capacity is established. – If the underlying GIC in the microwave band has very strong interference, the optimal power allocation assigns the power budget entirely to the direct channels. – If the channel parameters satisfy one of the following criteria, transmitting only in the direct channels is approximately optimal, in the sense that the difference between the sum-rates resulting from allocating to only direct channels and allocating optimally in all channels, is negligibly small: (a) the transmit powers in the underlying GIC in the microwave band is very small; or (b) the cross channel gains in the mm-wave band are very large. We denote an n-length vector ( X1 , X2 , . . . , Xn ) by X n , the empty set by ∅, log x by log x, and define C( x ) := 21 log(1 + x )
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
