49 research outputs found
Coordination and Bargaining over the Gaussian Interference Channel
This work considers coordination and bargaining between two selfish users
over a Gaussian interference channel using game theory. The usual information
theoretic approach assumes full cooperation among users for codebook and rate
selection. In the scenario investigated here, each selfish user is willing to
coordinate its actions only when an incentive exists and benefits of
cooperation are fairly allocated. To improve communication rates, the two users
are allowed to negotiate for the use of a simple Han-Kobayashi type scheme with
fixed power split and conditions for which users have incentives to cooperate
are identified. The Nash bargaining solution (NBS) is used as a tool to get
fair information rates. The operating point is obtained as a result of an
optimization problem and compared with a TDM-based one in the literature.Comment: 5 pages, 4 figures, to appear in Proceedings of IEEE ISIT201
Optimal Signaling of MISO Full-Duplex Two-Way Wireless Channel
We model the self-interference in a multiple input single output (MISO)
full-duplex two-way channel and evaluate the achievable rate region. We
formulate the boundary of the achievable rate region termed as the Pareto
boundary by a family of coupled, non-convex optimization problems. Our main
contribution is decoupling and reformulating the original non-convex
optimization problems to a family of convex semidefinite programming problems.
For a MISO full-duplex two-way channel, we prove that beamforming is an optimal
transmission strategy which can achieve any point on the Pareto boundary.
Furthermore, we present a closed-form expression for the optimal beamforming
weights. In our numerical examples we quantify gains in the achievable rates of
the proposed beamforming over the zero-forcing beamforming.Comment: To appear in IEEE ICC 2015, London, U
Distributed downlink multi-cell processing requiring reduced-rate back-haul data exchange
Different-complexity Multi-Cell Processing (MCP) schemes employing Distributed Signal-to-Interference-Leakage-plus-Noise-Ratio (SILNR) precoding techniques are proposed, which require reduced back-haul data exchange in comparison to the conventional MCP structure. Our results demonstrate that the proposed structures are capable of increasing the achievable cell-edge throughput and offering different geographic rate profile distributions as well as meeting different delay requirements
Cooperative Downlink Multicell Preprocessing Relying on Reduced-Rate Back-Haul Data Exchange
Different-complexity multicell preprocessing (MCP) schemes employing distributed signal-to-interference leakageplus-noise ratio (SILNR) precoding techniques are proposed, which require reduced back-haul data exchange in comparison with the conventional MCP structure. Our results demonstrate that the proposed structures are capable of increasing the throughput achievable in the cell-edge area while offering different geographic rate profile distributions, as well as meeting different delay requirements
Alternating-Offer Bargaining Games over the Gaussian Interference Channel
This paper tackles the problem of how two selfish users jointly determine the
operating point in the achievable rate region of a two-user Gaussian
interference channel through bargaining. In previous work, incentive conditions
for two users to cooperate using a simple version of Han-Kobayashi scheme was
studied and the Nash bargaining solution (NBS) was used to obtain a fair
operating point. Here a noncooperative bargaining game of alternating offers is
adopted to model the bargaining process and rates resulting from the
equilibrium outcome are analyzed. In particular, it is shown that the operating
point resulting from the formulated bargaining game depends on the cost of
delay in bargaining and how bargaining proceeds. If the associated bargaining
problem is regular, a unique perfect equilibrium exists and lies on the
individual rational efficient frontier of the achievable rate region. Besides,
the equilibrium outcome approaches the NBS if the bargaining costs of both
users are negligible.Comment: 8 pages, 6 figures, to appear in Proceedings of Forty-Eighth Annual
Allerton Conference on Communication, Control, and Computin
Cross-layer distributed power control: A repeated games formulation to improve the sum energy-efficiency
The main objective of this work is to improve the energy-efficiency (EE) of a
multiple access channel (MAC) system, through power control, in a distributed
manner. In contrast with many existing works on energy-efficient power control,
which ignore the possible presence of a queue at the transmitter, we consider a
new generalized cross-layer EE metric. This approach is relevant when the
transmitters have a non-zero energy cost even when the radiated power is zero
and takes into account the presence of a finite packet buffer and packet
arrival at the transmitter. As the Nash equilibrium (NE) is an
energy-inefficient solution, the present work aims at overcoming this deficit
by improving the global energy-efficiency. Indeed, as the considered system has
multiple agencies each with their own interest, the performance metric
reflecting the individual interest of each decision maker is the global
energy-efficiency defined then as the sum over individual energy-efficiencies.
Repeated games (RG) are investigated through the study of two dynamic games
(finite RG and discounted RG), whose equilibrium is defined when introducing a
new operating point (OP), Pareto-dominating the NE and relying only on
individual channel state information (CSI). Accordingly, closed-form
expressions of the minimum number of stages of the game for finite RG (FRG) and
the maximum discount factor of the discounted RG (DRG) were established. The
cross-layer model in the RG formulation leads to achieving a shorter minimum
number of stages in the FRG even for higher number of users. In addition, the
social welfare (sum of utilities) in the DRG decreases slightly with the
cross-layer model when the number of users increases while it is reduced
considerably with the Goodman model. Finally, we show that in real systems with
random packet arrivals, the cross-layer power control algorithm outperforms the
Goodman algorithm.Comment: 36 pages, single column draft forma
Downlink Noncoherent Cooperation without Transmitter Phase Alignment
Multicell joint processing can mitigate inter-cell interference and thereby
increase the spectral efficiency of cellular systems. Most previous work has
assumed phase-aligned (coherent) transmissions from different base transceiver
stations (BTSs), which is difficult to achieve in practice. In this work, a
noncoherent cooperative transmission scheme for the downlink is studied, which
does not require phase alignment. The focus is on jointly serving two users in
adjacent cells sharing the same resource block. The two BTSs partially share
their messages through a backhaul link, and each BTS transmits a superposition
of two codewords, one for each receiver. Each receiver decodes its own message,
and treats the signals for the other receiver as background noise. With
narrowband transmissions the achievable rate region and maximum achievable
weighted sum rate are characterized by optimizing the power allocation (and the
beamforming vectors in the case of multiple transmit antennas) at each BTS
between its two codewords. For a wideband (multicarrier) system, a dual
formulation of the optimal power allocation problem across sub-carriers is
presented, which can be efficiently solved by numerical methods. Results show
that the proposed cooperation scheme can improve the sum rate substantially in
the low to moderate signal-to-noise ratio (SNR) range.Comment: 30 pages, 6 figures, submitted to IEEE Transactions on Wireless
Communication