Abstract
In coded bidirectional cooperation, two nodes wish to exchange messages over a shared half-duplex channel with the help of a relay. In this correspondence, we derive performance bounds for this problem for each of three decode-and-forward protocols. The first protocol is a two phase protocol where both users simultaneously transmit during the first phase and the relay alone transmits during the second. In this protocol, our bounds are tight. The second protocol considers sequential transmissions from the two users followed by a transmission from the relay while the third protocol is a hybrid of the first two protocols and has four phases. In the latter two protocols the bounds are not identical. Numerical evaluation shows that in some cases of interest our bounds do not differ significantly. Finally, in the Gaussian case with path loss, we derive achievable rates and compare the relative merits of each protocol. This case is of interest in cellular systems. Surprisingly, we find that in some cases, the achievable rate region of the four phase protocol contains points that are outside the outer bounds of the other two protocols.
Highlights
The first protocol is a two phase protocol where both users simultaneously transmit during the first phase and the relay alone transmits during the second
We find that in some cases, the achievable rate region of the four phase protocol contains points that are outside the outer bounds of the other two protocols
With a relay node r, we suggest three different decode-and-forward protocols, which we denote as multiple access broadcast (MABC) protocol, time division broadcast (TDBC), and hybrid broadcast (HBC)
Summary
Consider two users, denoted by a and b, who wish to share independent messages over a shared channel. The works of [7] and [8] consider the three phase protocol, but combine the first two phases into a single joint transmission by a b nodes and followed by a single transmission by the relay which forwards its received signal (Fig. 1). In [9], achievable rate regions are derived assuming full duplex capabilities at all nodes In this correspondence, we are interested in determining fundamental bounds on the performance of coded bidirectional communications assuming various decode-and-forward protocols for half-duplex channels. In the case of a two phase protocol where both users transmit simultaneously in the first phase followed by a transmission from the relay, we derive the exact performance..
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
