Development and Prospects of the Greek Cooperative Credit System

The credit cooperative system was established in Greece in 1993, following the creation of the appropriate legislative framework. The Greek system distinguishes two types of institutions: the cooperative bank that functions as a bank and the credit cooperative that cannot provide banking services. The Greek cooperative system is characterized by the autonomous and nonhomogenous development of the cooperative banks and credit cooperatives. Moreover, in 2001 the cooperative banks created a central nation-wide bank that has since helped the further development of the credit cooperative system. However and despite the large number of geographic departments involved in the credit cooperative system, the expansion of cooperative banks in the Greek bank market is limited, principally due to legislative restrictions and the lack of dynamism these restrictions create to the credit cooperative system, while operating in a very competitive market environment.Cooperative bank, Credit union, Credit cooperative, Cooperative credit system, Greece, Agribusiness,

Truthful Mechanisms for Secure Communication in Wireless Cooperative System

To ensure security in data transmission is one of the most important issues for wireless relay networks, and physical layer security is an attractive alternative solution to address this issue. In this paper, we consider a cooperative network, consisting of one source node, one destination node, one eavesdropper node, and a number of relay nodes. Specifically, the source may select several relays to help forward the signal to the corresponding destination to achieve the best security performance. However, the relays may have the incentive not to report their true private channel information in order to get more chances to be selected and gain more payoff from the source. We propose a Vickey-Clark-Grove (VCG) based mechanism and an Arrow-d'Aspremont-Gerard-Varet (AGV) based mechanism into the investigated relay network to solve this cheating problem. In these two different mechanisms, we design different "transfer payment" functions to the payoff of each selected relay and prove that each relay gets its maximum (expected) payoff when it truthfully reveals its private channel information to the source. And then, an optimal secrecy rate of the network can be achieved. After discussing and comparing the VCG and AGV mechanisms, we prove that the AGV mechanism can achieve all of the basic qualifications (incentive compatibility, individual rationality and budget balance) for our system. Moreover, we discuss the optimal quantity of relays that the source node should select. Simulation results verify efficiency and fairness of the VCG and AGV mechanisms, and consolidate these conclusions.Comment: To appear in IEEE Transactions on Wireless Communication

On the energy efficiency-spectral efficiency trade-off in the uplink of CoMP system

In this paper, we derive a generic closed-form approximation (CFA) of the energy efficiency-spectral efficiency (EE-SE) trade-off for the uplink of coordinated multi-point (CoMP) system and demonstrate its accuracy for both idealistic and realistic power consumption models (PCMs). We utilize our CFA to compare CoMP against conventional non-cooperative system with orthogonal multiple access. In the idealistic PCM, CoMP is more energy efficient than non-cooperative system due to a reduction in power consumption; whereas in the realistic PCM, CoMP can also be more energy efficient but due to an improvement in SE and mainly for cell-edge communication and small cell deployment

The Roles of a Consultant in a Cooperative System Headquarters

published or submitted for publicatio

A novel quantize-and-forward cooperative system : channel parameter estimation techniques

The Quantize and Forward cooperative communication protocol improves the reliability of data transmission by allowing a relay to forward to the destination a quantized version of the signal received from the source. In prior studies of the Quantize and Forward protocol, all channel parameters are assumed to be perfectly known at the destination, while in reality these need to be estimated. This paper proposes a novel Quantize and Forward protocol in which the relay compensates for the rotation on the source-relay channel using a crude channel estimate, before quantizing the phase of the received M-PSK data symbols. Therefore, as far as the source-relay channel is concerned, only an SNR estimate is needed at the destination. Further, the destination applies the EM algorithm to improve the estimates of the source-destination and relay-destination channel coefficients. The resulting performance is shown to be close to that of a system with known channel parameters