The Experts below are selected from a list of 38193 Experts worldwide ranked by ideXlab platform

Wenbo Wang - One of the best experts on this subject based on the ideXlab platform.

  • Joint Spectrum Allocation and Power Control for Multihop Cognitive Radio Networks
    IEEE Transactions on Mobile Computing, 2011
    Co-Authors: Wei Wang, Kang G. Shin, Wenbo Wang
    Abstract:

    We propose a new framework of joint spectrum allocation and power control to utilize open spectrum bands in cognitive radio networks (CRNs) by considering both Interference Temperature constraints and spectrum dynamics. We first address a simpler problem for the case of a single flow. A TDM-based power-control strategy is adopted to achieve maximum end-to-end throughput by choosing an appropriate multihop route and spectrum combination for each single flow. Then, the simpler solution is extended to the multiflow case in which interflow Interference and cumulative Interference Temperature must be considered. Considering the overhead of switching route and spectrum, the optimal waiting time before making a switch is derived. Our in-depth simulation study has shown that the proposed algorithms utilize spectrum more efficiently than other existing algorithms.

  • Efficient subcarrier and bit allocation under Interference Temperature constraints in OFDMA-based cognitive radio networks
    2010 3rd IEEE International Conference on Broadband Network and Multimedia Technology (IC-BNMT), 2010
    Co-Authors: Wenbo Wang
    Abstract:

    Cognitive radio makes it possible for an unlicensed user to access a spectrum opportunistically. This paper addresses the problem of assigning subcarriers and bits in uplink for OFDMA-based cognitive radio networks. The objective is to maximize the system throughput in the presence of Interference Temperature constraint. In this paper, an adaptive bit loading algorithm is proposed first, which converges faster than the traditional bit loading methods. Then a computationally efficient dynamic subcarrier allocation algorithm is devised using Lagrangian method of optimization. The key contribution of this algorithm is in three aspects. Firstly, a simplified rule is derived to guide the subcarrier assignment. Secondly, table lookup search is used in each iteration. Thirdly, the multiplicative search of Lagrangian-multiplier speedups the convergence. Combining the two algorithms, the subcarrier and bits allocation scheme for uplink is presented. The performance of the proposed scheme is investigated by numerical results.

  • CIT - Performance Analysis of Secondary Users in Dynamic Spectrum Access under Interference Temperature Constraints
    2010 10th IEEE International Conference on Computer and Information Technology, 2010
    Co-Authors: Zhi Yan, Xing Zhang, Wenbo Wang
    Abstract:

    In order to fully utilize the scarce spectrum resources and improve the efficiency of wireless spectrum resource utilization, dynamic spectrum access is proposed as a solution. There are two kinds of dynamic spectrum access system, one is overlay dynamic spectrum, and the other is dynamic spectrum access under Interference Temperature constraints. In this paper, we use a three-dimensional Markov chain to model the dynamic spectrum access under Interference Temperature constraints, and analyze the performance of secondary users in the system. Two important parameters, i.e., secondary user interrupting probability and blocking probability are derived using the proposed model. The performance of secondary users in different dynamic spectrum access systems are analyzed and compared. The numerical results show that the performance of secondary users can be improved significantly in dynamic spectrum access under Interference Temperature constraints comparing to overlay dynamic spectrum access. Specially, the advantage of Interference Temperature constraints based dynamic spectrum access is more notable on the condition that there are not enough resources to provide to secondary users for access.

  • optimal subcarrier and power allocation under Interference Temperature constraints
    Wireless Communications and Networking Conference, 2009
    Co-Authors: Tao Peng, Wei Wang, Wenbo Wang
    Abstract:

    Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of resource allocation for multiaccess channel (MAC) of OFDMA-based cognitive radio networks, taking into account of the Interference Temperature constraints. The objective is to maximize the system utility, which is used to quantify different quality-of-service (QoS) requirements of different users. Firstly, a theoretical framework is provided, where necessary and sufficient conditions for optimal subcarrier assignment and power allocation are presented under certain constraints. Then, an effective algorithm is devised for more practical conditions based on Lagrangian duality theory, where subgradient/ellipsoid method is applied for Lagrangian multipliers iteration. With polynomial time complexities, the proposed resource allocation algorithm is proved to achieve optimal system performance by numerical results.

  • WCNC - Optimal Subcarrier and Power Allocation under Interference Temperature Constraints
    2009 IEEE Wireless Communications and Networking Conference, 2009
    Co-Authors: Tao Peng, Wei Wang, Wenbo Wang
    Abstract:

    Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of resource allocation for multiaccess channel (MAC) of OFDMA-based cognitive radio networks, taking into account of the Interference Temperature constraints. The objective is to maximize the system utility, which is used to quantify different quality-of-service (QoS) requirements of different users. Firstly, a theoretical framework is provided, where necessary and sufficient conditions for optimal subcarrier assignment and power allocation are presented under certain constraints. Then, an effective algorithm is devised for more practical conditions based on Lagrangian duality theory, where subgradient/ellipsoid method is applied for Lagrangian multipliers iteration. With polynomial time complexities, the proposed resource allocation algorithm is proved to achieve optimal system performance by numerical results.

K P Subbalakshmi - One of the best experts on this subject based on the ideXlab platform.

  • dynamic spectrum access with qos and Interference Temperature constraints
    IEEE Transactions on Mobile Computing, 2007
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    Spectrum is one of the most precious radio resources. With the increasing demand for wireless communication, efficiently using the spectrum resource has become an essential issue. With the Federal Communications Commission's (FCC) spectrum policy reform, secondary spectrum sharing has gained increasing interest. One of the policy reforms introduces the concept of an Interference Temperature - the total allowable Interference in a spectral band. This means that secondary users can use different transmit powers as long as the sum of these power is less than the Interference threshold. In this paper, we study two problems in secondary spectrum access with minimum signal to Interference noise ratio (quality of service (QoS)) guarantee under an Interference Temperature constraint. First, when all the secondary links can be supported, a nonlinear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The nonlinear optimization is solved efficiently using geometric programming techniques. The second problem we address is, when not all the secondary links can be supported with their QoS requirement, it is desirable to have the spectrum access opportunity proportional to the user priority if they belong to different priority classes. In this context, we formulate an operator problem which takes the priority issues into consideration. To solve this problem, first, we propose a centralized reduced complexity search algorithm to find the optimal solution. Then, in order to solve this problem distributively, we define a secondary spectrum sharing potential game. The Nash equilibria of this potential game are investigated. The efficiency of the Nash equilibria solutions are characterized. It is shown that distributed sequential play and an algorithm based on stochastic learning attain the equilibrium solutions. Finally, the performances are examined through simulations

  • priority based dynamic spectrum access with qos and Interference Temperature constraints
    International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • ICC - Priority Based Dynamic Spectrum Access with QoS and Interference Temperature Constraints
    2006 IEEE International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • CCNC - Real-time secondary spectrum sharing with QoS provisioning
    CCNC 2006. 2006 3rd IEEE Consumer Communications and Networking Conference 2006., 1
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the quality of service (QoS) issue in sec- ondary spectrum sharing subject to an Interference Temperature constraint. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity searching algorithm is introduced to find the optimal subset of links which contains the maximum number of links with both QoS and Interference Temperature constraints satisfied. We also defined a secondary spectrum sharing potential game. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions is characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations. I. INTRODUCTION Enhancing spectrum efficiency and use is a significant task of regulatory authorities worldwide. A number of mea- surement studies of spectrum utilization have indicated that spectrum is sporadically used in many geographical areas and times. Low utilization and increased demand for the radio resource suggests the notion of secondary use, which allows unused parts of spectrum to become available temporarily. The secondary use of spectrum is one of the promising ideas that can mitigate unsatisfied spectrum demand, potentially without major changes to incumbents. Then, the question comes to how to share the available spectrum efficiently and fairly. The FCC spectrum Policy Task Force (1) has recommended a paradigm shift in Interference assessment, that is, a shift away from largely fixed operations in the transmitter and toward real-time interactions between the transmitter and receiver in an adaptive manner. The recommendation is based on a new metric called the Interference Temperature, which is intended to quantify and manage the sources of Interference in a radio environment. The Interference Temperature is defined to be the RF power measured at a receiving antenna per unit bandwidth. The key idea for this new metric is that, firstly, the Interference Temperature at a receiving antenna provides an accurate measure for the acceptable level of RF Interference in the frequency band of interest; any transmission in that band is considered to be "harmful" if it would increase the noise floor above the Interference Temperature threshold. Secondly, given a particular frequency band in which the Interference Temperature is not exceeded, that band could be made available to secondary users. Hence, a secondary device might attempt to coexist with the primary, such that the presence of secondary devices goes unnoticed.

Yiping Xing - One of the best experts on this subject based on the ideXlab platform.

  • dynamic spectrum access with qos and Interference Temperature constraints
    IEEE Transactions on Mobile Computing, 2007
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    Spectrum is one of the most precious radio resources. With the increasing demand for wireless communication, efficiently using the spectrum resource has become an essential issue. With the Federal Communications Commission's (FCC) spectrum policy reform, secondary spectrum sharing has gained increasing interest. One of the policy reforms introduces the concept of an Interference Temperature - the total allowable Interference in a spectral band. This means that secondary users can use different transmit powers as long as the sum of these power is less than the Interference threshold. In this paper, we study two problems in secondary spectrum access with minimum signal to Interference noise ratio (quality of service (QoS)) guarantee under an Interference Temperature constraint. First, when all the secondary links can be supported, a nonlinear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The nonlinear optimization is solved efficiently using geometric programming techniques. The second problem we address is, when not all the secondary links can be supported with their QoS requirement, it is desirable to have the spectrum access opportunity proportional to the user priority if they belong to different priority classes. In this context, we formulate an operator problem which takes the priority issues into consideration. To solve this problem, first, we propose a centralized reduced complexity search algorithm to find the optimal solution. Then, in order to solve this problem distributively, we define a secondary spectrum sharing potential game. The Nash equilibria of this potential game are investigated. The efficiency of the Nash equilibria solutions are characterized. It is shown that distributed sequential play and an algorithm based on stochastic learning attain the equilibrium solutions. Finally, the performances are examined through simulations

  • priority based dynamic spectrum access with qos and Interference Temperature constraints
    International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • ICC - Priority Based Dynamic Spectrum Access with QoS and Interference Temperature Constraints
    2006 IEEE International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • CCNC - Real-time secondary spectrum sharing with QoS provisioning
    CCNC 2006. 2006 3rd IEEE Consumer Communications and Networking Conference 2006., 1
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the quality of service (QoS) issue in sec- ondary spectrum sharing subject to an Interference Temperature constraint. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity searching algorithm is introduced to find the optimal subset of links which contains the maximum number of links with both QoS and Interference Temperature constraints satisfied. We also defined a secondary spectrum sharing potential game. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions is characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations. I. INTRODUCTION Enhancing spectrum efficiency and use is a significant task of regulatory authorities worldwide. A number of mea- surement studies of spectrum utilization have indicated that spectrum is sporadically used in many geographical areas and times. Low utilization and increased demand for the radio resource suggests the notion of secondary use, which allows unused parts of spectrum to become available temporarily. The secondary use of spectrum is one of the promising ideas that can mitigate unsatisfied spectrum demand, potentially without major changes to incumbents. Then, the question comes to how to share the available spectrum efficiently and fairly. The FCC spectrum Policy Task Force (1) has recommended a paradigm shift in Interference assessment, that is, a shift away from largely fixed operations in the transmitter and toward real-time interactions between the transmitter and receiver in an adaptive manner. The recommendation is based on a new metric called the Interference Temperature, which is intended to quantify and manage the sources of Interference in a radio environment. The Interference Temperature is defined to be the RF power measured at a receiving antenna per unit bandwidth. The key idea for this new metric is that, firstly, the Interference Temperature at a receiving antenna provides an accurate measure for the acceptable level of RF Interference in the frequency band of interest; any transmission in that band is considered to be "harmful" if it would increase the noise floor above the Interference Temperature threshold. Secondly, given a particular frequency band in which the Interference Temperature is not exceeded, that band could be made available to secondary users. Hence, a secondary device might attempt to coexist with the primary, such that the presence of secondary devices goes unnoticed.

Linda Doyle - One of the best experts on this subject based on the ideXlab platform.

  • modelling Interference Temperature constraints for spectrum access in cognitive radio networks
    International Conference on Communications, 2007
    Co-Authors: Joe Bater, Hwee-pink Tan, Kenneth N. Brown, Linda Doyle
    Abstract:

    With the advent of cognitive radio technology, new paradigms for spectrum access can achieve near-optimal spectrum utilisation by letting each user sense and utilise available spectrum opportunistically while regulating the Interference it imposes on other users through Interference constraints. However, the simplest and most common forms of such constraints are binary and transmitter-centric, which are often inefficient since they only consider pair-wise sets of transmitters. Hence, we propose a non-binary receiver-centric constraint model for spectrum access in cognitive radio networks. Such a model is in line with the recently proposed Interference Temperature metric that constraints whole subsets of transmitters, thereby permitting interfering signals to be introduced and enabling additional communication, leading to improved spectrum utilisation. These constraints are easy to generate and check, and are currently being used to devise a co-operative negotiated etiquette for cognitive radios offering heterogeneous services in a wireless office networking scenario.

  • CrownCom - Maximising Access to a Spectrum Commons using Interference Temperature Constraints
    2007 2nd International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2007
    Co-Authors: Joe Bater, Hwee-pink Tan, Kenneth N. Brown, Linda Doyle
    Abstract:

    We propose a new spectrum-access etiquette for cognitive radios in a spectrum commons. When congestion might block a new device from initiating a call, the surrounding devices coordinate their actions and locally reassign their spectrum to create a gap for the new entrant. The etiquette is designed for devices operating dissimilar services with different bandwidth and quality requirements. It generates link-level Interference Temperature constraints and finds a satisfying assignment using local search. In experimental simulation, we demonstrate that the etiquette provides significantly higher completion rates while improving the quality of the completed calls.

  • ICC - Modelling Interference Temperature Constraints for Spectrum Access in Cognitive Radio Networks
    2007 IEEE International Conference on Communications, 2007
    Co-Authors: Joe Bater, Hwee-pink Tan, Kenneth N. Brown, Linda Doyle
    Abstract:

    With the advent of cognitive radio technology, new paradigms for spectrum access can achieve near-optimal spectrum utilisation by letting each user sense and utilise available spectrum opportunistically while regulating the Interference it imposes on other users through Interference constraints. However, the simplest and most common forms of such constraints are binary and transmitter-centric, which are often inefficient since they only consider pair-wise sets of transmitters. Hence, we propose a non-binary receiver-centric constraint model for spectrum access in cognitive radio networks. Such a model is in line with the recently proposed Interference Temperature metric that constraints whole subsets of transmitters, thereby permitting interfering signals to be introduced and enabling additional communication, leading to improved spectrum utilisation. These constraints are easy to generate and check, and are currently being used to devise a co-operative negotiated etiquette for cognitive radios offering heterogeneous services in a wireless office networking scenario.

R Chandramouli - One of the best experts on this subject based on the ideXlab platform.

  • dynamic spectrum access with qos and Interference Temperature constraints
    IEEE Transactions on Mobile Computing, 2007
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    Spectrum is one of the most precious radio resources. With the increasing demand for wireless communication, efficiently using the spectrum resource has become an essential issue. With the Federal Communications Commission's (FCC) spectrum policy reform, secondary spectrum sharing has gained increasing interest. One of the policy reforms introduces the concept of an Interference Temperature - the total allowable Interference in a spectral band. This means that secondary users can use different transmit powers as long as the sum of these power is less than the Interference threshold. In this paper, we study two problems in secondary spectrum access with minimum signal to Interference noise ratio (quality of service (QoS)) guarantee under an Interference Temperature constraint. First, when all the secondary links can be supported, a nonlinear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The nonlinear optimization is solved efficiently using geometric programming techniques. The second problem we address is, when not all the secondary links can be supported with their QoS requirement, it is desirable to have the spectrum access opportunity proportional to the user priority if they belong to different priority classes. In this context, we formulate an operator problem which takes the priority issues into consideration. To solve this problem, first, we propose a centralized reduced complexity search algorithm to find the optimal solution. Then, in order to solve this problem distributively, we define a secondary spectrum sharing potential game. The Nash equilibria of this potential game are investigated. The efficiency of the Nash equilibria solutions are characterized. It is shown that distributed sequential play and an algorithm based on stochastic learning attain the equilibrium solutions. Finally, the performances are examined through simulations

  • priority based dynamic spectrum access with qos and Interference Temperature constraints
    International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • ICC - Priority Based Dynamic Spectrum Access with QoS and Interference Temperature Constraints
    2006 IEEE International Conference on Communications, 2006
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the problem of dynamic spectrum access by secondary users with minimum signal to Interference noise ratio (quality of service (QoS)) and Interference Temperature constraints. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity search algorithm is introduced to find the optimal subset of allowable links. Secondary users may belong to different priority classes. Accessing opportunities should be proportional to priorities. Therefore, we defined a secondary spectrum sharing potential game which takes these priority classes into consideration. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions are characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations.

  • CCNC - Real-time secondary spectrum sharing with QoS provisioning
    CCNC 2006. 2006 3rd IEEE Consumer Communications and Networking Conference 2006., 1
    Co-Authors: Yiping Xing, Chetan Nanjunda Mathur, M A Haleem, R Chandramouli, K P Subbalakshmi
    Abstract:

    We study the quality of service (QoS) issue in sec- ondary spectrum sharing subject to an Interference Temperature constraint. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. When not all the secondary links can be supported with their QoS requirement, a reduced complexity searching algorithm is introduced to find the optimal subset of links which contains the maximum number of links with both QoS and Interference Temperature constraints satisfied. We also defined a secondary spectrum sharing potential game. The Nash equilibria of this potential game are reached by distributed sequential play. The efficiency of the Nash equilibria solutions is characterized. Finally, the performances of both the reduced complexity algorithm and the sequential play are examined through simulations. I. INTRODUCTION Enhancing spectrum efficiency and use is a significant task of regulatory authorities worldwide. A number of mea- surement studies of spectrum utilization have indicated that spectrum is sporadically used in many geographical areas and times. Low utilization and increased demand for the radio resource suggests the notion of secondary use, which allows unused parts of spectrum to become available temporarily. The secondary use of spectrum is one of the promising ideas that can mitigate unsatisfied spectrum demand, potentially without major changes to incumbents. Then, the question comes to how to share the available spectrum efficiently and fairly. The FCC spectrum Policy Task Force (1) has recommended a paradigm shift in Interference assessment, that is, a shift away from largely fixed operations in the transmitter and toward real-time interactions between the transmitter and receiver in an adaptive manner. The recommendation is based on a new metric called the Interference Temperature, which is intended to quantify and manage the sources of Interference in a radio environment. The Interference Temperature is defined to be the RF power measured at a receiving antenna per unit bandwidth. The key idea for this new metric is that, firstly, the Interference Temperature at a receiving antenna provides an accurate measure for the acceptable level of RF Interference in the frequency band of interest; any transmission in that band is considered to be "harmful" if it would increase the noise floor above the Interference Temperature threshold. Secondly, given a particular frequency band in which the Interference Temperature is not exceeded, that band could be made available to secondary users. Hence, a secondary device might attempt to coexist with the primary, such that the presence of secondary devices goes unnoticed.