203 research outputs found
Non-cooperative Feedback Rate Control Game for Channel State Information in Wireless Networks
It has been well recognized that channel state information (CSI) feedback is
of great importance for dowlink transmissions of closed-loop wireless networks.
However, the existing work typically researched the CSI feedback problem for
each individual mobile station (MS), and thus, cannot efficiently model the
interactions among self-interested mobile users in the network level. To this
end, in this paper, we propose an alternative approach to investigate the CSI
feedback rate control problem in the analytical setting of a game theoretic
framework, in which a multiple-antenna base station (BS) communicates with a
number of co-channel MSs through linear precoder. Specifically, we first
present a non-cooperative feedback-rate control game (NFC), in which each MS
selects the feedback rate to maximize its performance in a distributed way. To
improve efficiency from a social optimum point of view, we then introduce
pricing, called the non-cooperative feedback-rate control game with price
(NFCP). The game utility is defined as the performance gain by CSI feedback
minus the price as a linear function of the CSI feedback rate. The existence of
the Nash equilibrium of such games is investigated, and two types of feedback
protocols (FDMA and CSMA) are studied. Simulation results show that by
adjusting the pricing factor, the distributed NFCP game results in close
optimal performance compared with that of the centralized scheme.Comment: 26 pages, 10 figures; IEEE Journal on Selected Areas in
Communications, special issue on Game Theory in Wireless Communications, 201
Completion Delay of Random Linear Network Coding in Full-Duplex Relay Networks
As the next-generation wireless networks thrive, full-duplex and relaying
techniques are combined to improve the network performance. Random linear
network coding (RLNC) is another popular technique to enhance the efficiency
and reliability in wireless communications. In this paper, in order to explore
the potential of RLNC in full-duplex relay networks, we investigate two
fundamental perfect RLNC schemes and theoretically analyze their completion
delay performance. The first scheme is a straightforward application of
conventional perfect RLNC studied in wireless broadcast, so it involves no
additional process at the relay. Its performance serves as an upper bound among
all perfect RLNC schemes. The other scheme allows sufficiently large buffer and
unconstrained linear coding at the relay. It attains the optimal performance
and serves as a lower bound among all RLNC schemes. For both schemes,
closed-form formulae to characterize the expected completion delay at a single
receiver as well as for the whole system are derived. Numerical results are
also demonstrated to justify the theoretical characterizations, and compare the
two new schemes with the existing one
Primitive Zero-Symmetric Sign Pattern Matrices with Zero Diagonal Attaining the Maximum Base
The base set of primitive zero-symmetric sign pattern matrices with zero diagonal is {1,2,..., 2n -1}. In this paper, the primitive zero-symmetric sign pattern matrices with zero diagonal attaining the maximal base 2n - 1 are characterized
Full-duplex wireless communications: challenges, solutions and future research directions
The family of conventional half-duplex (HD) wireless systems relied on transmitting and receiving in different time-slots or frequency sub-bands. Hence the wireless research community aspires to conceive full-duplex (FD) operation for supporting concurrent transmission and reception in a single time/frequency channel, which would improve the attainable spectral efficiency by a factor of two. The main challenge encountered in implementing an FD wireless device is the large power difference between the self-interference (SI) imposed by the device’s own transmissions and the signal of interest received from a remote source. In this survey, we present a comprehensive list of the potential FD techniques and highlight their pros and cons. We classify the SI cancellation techniques into three categories, namely passive suppression, analog cancellation and digital cancellation, with the advantages and disadvantages of each technique compared. Specifically, we analyse the main impairments (e.g. phase noise, power amplifier nonlinearity as well as in-phase and quadrature-phase (I/Q) imbalance, etc.) that degrading the SI cancellation. We then discuss the FD based Media Access Control (MAC)-layer protocol design for the sake of addressing some of the critical issues, such as the problem of hidden terminals, the resultant end-to-end delay and the high packet loss ratio (PLR) due to network congestion. After elaborating on a variety of physical/MAC-layer techniques, we discuss potential solutions conceived for meeting the challenges imposed by the aforementioned techniques. Furthermore, we also discuss a range of critical issues related to the implementation, performance enhancement and optimization of FD systems, including important topics such as hybrid FD/HD scheme, optimal relay selection and optimal power allocation, etc. Finally, a variety of new directions and open problems associated with FD technology are pointed out. Our hope is that this treatise will stimulate future research efforts in the emerging field of FD communication
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