Physical Layer Integration of Private, Common, and Confidential Messages in Bidirectional Relay Networks

Abstract

In order to increase spectral efficiency, it is becoming more and more important that next generation wireless networks wisely integrate multiple services such as transmissions of private, common, and confidential messages at the physical layer. This is referred to as physical layer service integration, and in this paper is being studied for bidirectional relay networks. Here, a relay node establishes a bidirectional communication between two other nodes using a decode-and-forward protocol. This is also known as two-way relaying. In the broadcast phase, the relay efficiently integrates additional common and confidential services at the physical layer, which then requires the study of the bidirectional broadcast channel (BBC) with common and confidential messages. The entire secrecy capacity regions for discrete memoryless and MIMO Gaussian channels are established. These results further unify previous partial results such as the BBC with common messages or the classical broadcast channel with common and confidential messages, where the relay node provides only some of the services.

Bidirectional relay communication with additional private message

“…As in [16,62,63], we consider two different kinds of power constraints: a total power constraint and a covariance constraint. An input sequence x n = (x 1 , x 2 , .…”

“…Other ongoing research activities on bidirectional relaying and its extensions can be found in [16] where private, common and confidential messages are integrated in the bidirectional relay networks, in [17] where a survey of different processing strategies is provided, in [18] where the efficient integration of bidirectional relaying in a cellular downlink is presented and in [19][20][21] where bidirectional relaying for multiple pairs of nodes is analyzed. Further, bidirectional relaying with an additional private message for the relay in the MAC phase is addressed in [22] and beamforming strategies for multi-antenna bidirectional relaying with analog network coding is presented in [23].…”

“…Now, in an exact correspondance to region (5.6), we can write that R(Q 12 , Q p ) is the set of all rate triples (R p , R 1 , R 2 ) ∈ R 3 + that satisfy Now we consider a slightly different problem. As in [63] and [16], instead of finding the best possible rates for a given power constraint, we find the minimum power required to achieve a set of minimal rate requirements. Furthermore, instead of considering the rates themselves, we can equivalently give minimum requirements on the SNIRs of the different users.…”

Artificial noise-aided biobjective transmitter optimization for service integration in multi-user MIMO broadcast channel

“…Under discrete memoryless broadcast channel (DMBC) setup, Csiszár and Körner gave a closed-form expression of the maximum rate region that can be applied reliably under the secrecy constraint (i.e., the secrecy capacity region). In recent years, this kind of approach has gained renewed interest, especially that in various multi-antenna scenarios, such as Gaussian broadcast channels [12]- [15], and bidirectional relay channels [16], [17]. In [12], the authors extended the results in [11] to a general MIMO Gaussian case by adopting the channel-enhancement argument.…”

“…The resulting secrecy capacity region is proved to be attainable by combining the secret dirtypaper coding (S-DPC) with Gaussian superposition coding. Furthermore, in [16] and [17], Wyrembelski and Boche amalgamated broadcast service, multicast service and confidential service in bidirectional relay networks, in which a relay adds an additional multicast message for all nodes and a confidential message for only one node besides establishing the conventional bidirectional communication. Nonetheless, the main goal of the aforementioned papers is just to obtain capacity results or to characterize coding strategies that lead to certain rate regions [18].…”