A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS...A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.展开更多
In modem financial markets, the credit default swap （CDS） market has supplanted the bond market as the industry gauge for a borrower＇s credit quality. Therefore, it is very important to value CDS accurately by gett...In modem financial markets, the credit default swap （CDS） market has supplanted the bond market as the industry gauge for a borrower＇s credit quality. Therefore, it is very important to value CDS accurately by getting closer to more realistic pricing models. So far there have been no models for extracting forward-looking credit information to value CDS. In current practice, historical data is used in a credit default swap pricing model. One of the reasons was the difficulty when the market for credit derivatives was small, to extract forward-looking credit information such as recovery rates and default probabilities from traded securities. Since the CDS market has undergone rapid expansion in recent years, the possibilities of extracting forward-looking credit information have increased. Our work significantly extends Das and Hanouma （2009） where a flexible jump-to-default model was introduced to obtain implied recovery rates. We improve the flexible jump-to-default model where forecasted forward-looking hazard rates and recovery rates can be extracted using stock prices, stock volatilities and data from credit default markets to forecast CDS spreads. Instead of using exogenously assumed constant recovery rates and default probabilities from a credit rating agency, we use forward-looking hazard rates and recovery rates to price and forecast CDS spreads. We also compare out-of-sample market CDS spreads with our forecasted CDS spreads to check how well our model performs. Our model fit the market CDS spreads very well across all time to maturity CDS contracts except in some extreme cases when there is a big jump in CDS spreads.展开更多
The objective of this paper is to measure the risk charge for credit risk as one of the components in the risk based capital of the capital adequacy framework. Currently, the risk charge for credit risk is measured by...The objective of this paper is to measure the risk charge for credit risk as one of the components in the risk based capital of the capital adequacy framework. Currently, the risk charge for credit risk is measured by referring it to the credit rating of a company. Following the subprime crisis in 2007, the markets start to question the soundness of the credit rating issued as it has resulted in an inadequate risk charge. Therefore, this study attempts to determine the risk charge for credit risk using the probability of default （PD） for life insurers in Malaysia. The credit risk has been categorized into several types of debt obligations. Whereby, the KMV-Merton model has been used to measure the distance to default and estimate the probability of default. The estimation of default probability is based on the movement in the price index of several debt obligations. The price index of debt obligations from year 2004 to 2009 is collected inclusive of the subprime crisis period during the crisis period. Therefore, Malaysia insurance industry is The results found that the risk charges are lower not affected by the subprime crisis in 2007.展开更多
基金The National Science and Technology M ajor Project(No.2012ZX03004005-003)the National Natural Science Foundation of China(No.61171081,61201175)the Research Fund of National M obile Communications Research Laboratory of Southeast University(No.2014A03)
文摘A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.
文摘In modem financial markets, the credit default swap （CDS） market has supplanted the bond market as the industry gauge for a borrower＇s credit quality. Therefore, it is very important to value CDS accurately by getting closer to more realistic pricing models. So far there have been no models for extracting forward-looking credit information to value CDS. In current practice, historical data is used in a credit default swap pricing model. One of the reasons was the difficulty when the market for credit derivatives was small, to extract forward-looking credit information such as recovery rates and default probabilities from traded securities. Since the CDS market has undergone rapid expansion in recent years, the possibilities of extracting forward-looking credit information have increased. Our work significantly extends Das and Hanouma （2009） where a flexible jump-to-default model was introduced to obtain implied recovery rates. We improve the flexible jump-to-default model where forecasted forward-looking hazard rates and recovery rates can be extracted using stock prices, stock volatilities and data from credit default markets to forecast CDS spreads. Instead of using exogenously assumed constant recovery rates and default probabilities from a credit rating agency, we use forward-looking hazard rates and recovery rates to price and forecast CDS spreads. We also compare out-of-sample market CDS spreads with our forecasted CDS spreads to check how well our model performs. Our model fit the market CDS spreads very well across all time to maturity CDS contracts except in some extreme cases when there is a big jump in CDS spreads.
文摘The objective of this paper is to measure the risk charge for credit risk as one of the components in the risk based capital of the capital adequacy framework. Currently, the risk charge for credit risk is measured by referring it to the credit rating of a company. Following the subprime crisis in 2007, the markets start to question the soundness of the credit rating issued as it has resulted in an inadequate risk charge. Therefore, this study attempts to determine the risk charge for credit risk using the probability of default （PD） for life insurers in Malaysia. The credit risk has been categorized into several types of debt obligations. Whereby, the KMV-Merton model has been used to measure the distance to default and estimate the probability of default. The estimation of default probability is based on the movement in the price index of several debt obligations. The price index of debt obligations from year 2004 to 2009 is collected inclusive of the subprime crisis period during the crisis period. Therefore, Malaysia insurance industry is The results found that the risk charges are lower not affected by the subprime crisis in 2007.
