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Xin Kang - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Power Allocation strategies for fading cognitive radio channels with primary user outage constraint
    IEEE Journal on Selected Areas in Communications, 2011
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a cognitive radio (CR) network where a secondary (cognitive) user shares the spectrum for transmission with a primary (non-cognitive) user over block-fading (BF) channels. It is assumed that the primary user has a constant-rate, constant-Power transmission, while the secondary user is able to adapt transmit Power and rate Allocation over different fading states based on the channel state information (CSI) of the CR network. We study a new type of constraint imposed over the secondary transmission to protect the primary user by limiting the maximum transmission outage probability of the primary user to be below a desired target. We derive the Optimal Power Allocation strategies for the secondary user to maximize its ergodic/outage capacity, under the average/peak transmit Power constraint along with the proposed primary user outage probability constraint. It is shown by simulations that the derived new Power Allocation strategies can achieve substantial capacity gains for the secondary user over the conventional methods based on the interference temperature (IT) constraint to protect the primary transmission, with the same resultant primary user outage probability.

  • Optimal Power Allocation for OFDM-based cognitive radio with new primary transmission protection criteria
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Xin Kang, Yingchang Liang, H K Garg, Rui Zhang
    Abstract:

    This paper considers a spectrum underlay network, where an OFDM-based cognitive radio (CR) system is allowed to share the subcarriers of an OFDMA-based primary system for simultaneous transmission. Instead of using the conventional interference Power constraint (IPC) to protect the primary users (PUs) in the primary system, a new criterion referred to as rate loss constraint (RLC), in the form of an upper bound on the maximum rate loss of each PU due to the CR transmission, is proposed for primary transmission protection. Assuming the channel state information (CSI) of the PU link, the CR link, and their mutual interference links is available to the CR, the Optimal Power Allocation strategy to maximize the achievable rate of the CR system is derived under RLC together with CR?s transmit Power constraint. It is shown that the CR system can achieve a significant rate gain under RLC as compared to IPC. Furthermore, the relationship between RLC and IPC is investigated, and it is shown that the rate gain is obtained by exploiting the additional CSI of the PU link. A more general case referred to as hybrid protection to PUs is then studied, by taking into account that some PU links? CSI is not available at CR.

  • Optimal Power Allocation for cognitive radio under primary user s outage loss constraint
    International Conference on Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a secondary link sharing the spectrum with a primary link in a fading cognitive radio (CR) network. Instead of applying the conventional interference Power constraint at the primary user (PU) receiver for the secondary user (SU) to protect the primary transmission, we propose a new constraint on the maximum tolerable outage probability for the PU due to the SU transmission. Under the assumption that perfect instantaneous channel state information (CSI) on the SU channel, the channel from the SU transmitter to PU receiver, and the PU channel is available at the SU transmitter, we derive the Optimal Power Allocation strategies to achieve the ergodic capacity of the SU fading channel. It is shown by simulations that the proposed Power Allocation strategies can achieve substantial capacity gain for the SU over that based on the conventional interference Power constraint, for the same PU outage probability loss.

  • Optimal Power Allocation for fading channels in cognitive radio networks ergodic capacity and outage capacity
    IEEE Transactions on Wireless Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Arumugam Nallanathan, H K Garg, Rui Zhang
    Abstract:

    A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) in a secondary communication network (SCN) to opportunistically operate in the frequency bands originally allocated to a primary communication network (PCN) or by allowing SCN to coexist with the primary users (PUs) in PCN as long as the interference caused by SCN to each PU is properly regulated. In this paper, we consider the latter case, known as spectrum sharing, and study the Optimal Power Allocation strategies to achieve the ergodic capacity and the outage capacity of the SU fading channel under different types of Power constraints and fading channel models. In particular, besides the interference Power constraint at PU, the transmit Power constraint of SU is also considered. Since the transmit Power and the interference Power can be limited either by a peak or an average constraint, various combinations of Power constraints are studied. It is shown that there is a capacity gain for SU under the average over the peak transmit/interference Power constraint. It is also shown that fading for the channel between SU transmitter and PU receiver is usually a beneficial factor for enhancing the SU channel capacities.

  • Optimal Power Allocation for fading channels in cognitive radio networks under transmit and interference Power constraints
    International Conference on Communications, 2008
    Co-Authors: Xin Kang, Yingchang Liang, Arumugam Nallanathan
    Abstract:

    In this paper, we study the Optimal Power control policies for fading channels in cognitive radio networks considering both the transmit and the interference Power constraints. For each of the constraints, the peak Power and the average Power are investigated. We derive the Optimal Power Allocation strategies in terms of maximizing the ergodic capacity of the secondary user when the channel state information is available to the transmitter and the receiver. It is shown that the Optimal Power adaption for each case has its own features, and is quite different from one to another. Finally, the numerical results are presented to validate the proposed Power Allocation methods for various Power constraint region.

Rui Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Power Allocation for outage probability minimization in fading channels with energy harvesting constraints
    IEEE Transactions on Wireless Communications, 2014
    Co-Authors: Chuan Huang, Rui Zhang, Shuguang Cui
    Abstract:

    This paper studies the Optimal Power Allocation for outage probability minimization in point-to-point fading channels with the energy-harvesting constraints and channel distribution information (CDI) at the transmitter. Both the cases with non-causal and causal energy state information (ESI) are considered, which correspond to the energy-harvesting (EH) rates being known and unknown prior to the transmissions, respectively. For the non-causal ESI case, the average outage probability minimization problem over a finite horizon of N EH periods is shown to be non-convex for a large class of practical fading channels. However, the globally Optimal "offline" Power Allocation is obtained by a forward search algorithm with at most N one-dimensional searches, and the Optimal Power profile is shown to be non-decreasing over time and have an interesting "save-then-transmit" structure. In particular, for the special case of N=1, our result revisits the classic outage capacity for fading channels with uniform Power Allocation. Moreover, for the case with causal ESI, we propose both the Optimal and subOptimal "online" Power Allocation algorithms, by applying the technique of dynamic programming and exploring the structure of Optimal offline solutions, respectively.

  • outage minimization in fading channels Optimal Power Allocation with channel distribution information known at transmitter
    Global Communications Conference, 2012
    Co-Authors: Chuan Huang, Rui Zhang, Shuguang Cui
    Abstract:

    This paper revisits the Optimal Power Allocation for outage minimization in the classic point-to-point fading channels with the channel distribution information (CDI) known at the transmitter. The channel state information (CSI) is assumed to be perfectly known at the receiver, but not available at the transmitter. In particular, we consider a finite horizon of N-block transmissions subject to an average Power constraint at the transmitter. Although minimizing the time-averaged per-block outage probability over each N-block transmission is shown to be a non-convex problem for a large class of practical fading channels, we show that the globally Optimal Power Allocation is obtainable by a simple one-dimensional search. It is shown that if the average transmit Power is above a certain threshold determined by the distribution of the fading channel and the target transmission rate, the uniform Power Allocation is Optimal; otherwise, an on-off Power Allocation is Optimal. Moreover, a subOptimal low-complexity Power Allocation scheme is proposed, which is shown to be asymptotically Optimal as N goes to infinity. Finally, numerical results are provided to validate our analysis.

  • Optimal Power Allocation strategies for fading cognitive radio channels with primary user outage constraint
    IEEE Journal on Selected Areas in Communications, 2011
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a cognitive radio (CR) network where a secondary (cognitive) user shares the spectrum for transmission with a primary (non-cognitive) user over block-fading (BF) channels. It is assumed that the primary user has a constant-rate, constant-Power transmission, while the secondary user is able to adapt transmit Power and rate Allocation over different fading states based on the channel state information (CSI) of the CR network. We study a new type of constraint imposed over the secondary transmission to protect the primary user by limiting the maximum transmission outage probability of the primary user to be below a desired target. We derive the Optimal Power Allocation strategies for the secondary user to maximize its ergodic/outage capacity, under the average/peak transmit Power constraint along with the proposed primary user outage probability constraint. It is shown by simulations that the derived new Power Allocation strategies can achieve substantial capacity gains for the secondary user over the conventional methods based on the interference temperature (IT) constraint to protect the primary transmission, with the same resultant primary user outage probability.

  • Optimal Power Allocation for OFDM-based cognitive radio with new primary transmission protection criteria
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Xin Kang, Yingchang Liang, H K Garg, Rui Zhang
    Abstract:

    This paper considers a spectrum underlay network, where an OFDM-based cognitive radio (CR) system is allowed to share the subcarriers of an OFDMA-based primary system for simultaneous transmission. Instead of using the conventional interference Power constraint (IPC) to protect the primary users (PUs) in the primary system, a new criterion referred to as rate loss constraint (RLC), in the form of an upper bound on the maximum rate loss of each PU due to the CR transmission, is proposed for primary transmission protection. Assuming the channel state information (CSI) of the PU link, the CR link, and their mutual interference links is available to the CR, the Optimal Power Allocation strategy to maximize the achievable rate of the CR system is derived under RLC together with CR?s transmit Power constraint. It is shown that the CR system can achieve a significant rate gain under RLC as compared to IPC. Furthermore, the relationship between RLC and IPC is investigated, and it is shown that the rate gain is obtained by exploiting the additional CSI of the PU link. A more general case referred to as hybrid protection to PUs is then studied, by taking into account that some PU links? CSI is not available at CR.

  • Optimal Power Allocation for cognitive radio under primary user s outage loss constraint
    International Conference on Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a secondary link sharing the spectrum with a primary link in a fading cognitive radio (CR) network. Instead of applying the conventional interference Power constraint at the primary user (PU) receiver for the secondary user (SU) to protect the primary transmission, we propose a new constraint on the maximum tolerable outage probability for the PU due to the SU transmission. Under the assumption that perfect instantaneous channel state information (CSI) on the SU channel, the channel from the SU transmitter to PU receiver, and the PU channel is available at the SU transmitter, we derive the Optimal Power Allocation strategies to achieve the ergodic capacity of the SU fading channel. It is shown by simulations that the proposed Power Allocation strategies can achieve substantial capacity gain for the SU over that based on the conventional interference Power constraint, for the same PU outage probability loss.

Jamie Evans - One of the best experts on this subject based on the ideXlab platform.

Yingchang Liang - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Power Allocation strategies for fading cognitive radio channels with primary user outage constraint
    IEEE Journal on Selected Areas in Communications, 2011
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a cognitive radio (CR) network where a secondary (cognitive) user shares the spectrum for transmission with a primary (non-cognitive) user over block-fading (BF) channels. It is assumed that the primary user has a constant-rate, constant-Power transmission, while the secondary user is able to adapt transmit Power and rate Allocation over different fading states based on the channel state information (CSI) of the CR network. We study a new type of constraint imposed over the secondary transmission to protect the primary user by limiting the maximum transmission outage probability of the primary user to be below a desired target. We derive the Optimal Power Allocation strategies for the secondary user to maximize its ergodic/outage capacity, under the average/peak transmit Power constraint along with the proposed primary user outage probability constraint. It is shown by simulations that the derived new Power Allocation strategies can achieve substantial capacity gains for the secondary user over the conventional methods based on the interference temperature (IT) constraint to protect the primary transmission, with the same resultant primary user outage probability.

  • Optimal Power Allocation for OFDM-based cognitive radio with new primary transmission protection criteria
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Xin Kang, Yingchang Liang, H K Garg, Rui Zhang
    Abstract:

    This paper considers a spectrum underlay network, where an OFDM-based cognitive radio (CR) system is allowed to share the subcarriers of an OFDMA-based primary system for simultaneous transmission. Instead of using the conventional interference Power constraint (IPC) to protect the primary users (PUs) in the primary system, a new criterion referred to as rate loss constraint (RLC), in the form of an upper bound on the maximum rate loss of each PU due to the CR transmission, is proposed for primary transmission protection. Assuming the channel state information (CSI) of the PU link, the CR link, and their mutual interference links is available to the CR, the Optimal Power Allocation strategy to maximize the achievable rate of the CR system is derived under RLC together with CR?s transmit Power constraint. It is shown that the CR system can achieve a significant rate gain under RLC as compared to IPC. Furthermore, the relationship between RLC and IPC is investigated, and it is shown that the rate gain is obtained by exploiting the additional CSI of the PU link. A more general case referred to as hybrid protection to PUs is then studied, by taking into account that some PU links? CSI is not available at CR.

  • Optimal Power Allocation for cognitive radio under primary user s outage loss constraint
    International Conference on Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a secondary link sharing the spectrum with a primary link in a fading cognitive radio (CR) network. Instead of applying the conventional interference Power constraint at the primary user (PU) receiver for the secondary user (SU) to protect the primary transmission, we propose a new constraint on the maximum tolerable outage probability for the PU due to the SU transmission. Under the assumption that perfect instantaneous channel state information (CSI) on the SU channel, the channel from the SU transmitter to PU receiver, and the PU channel is available at the SU transmitter, we derive the Optimal Power Allocation strategies to achieve the ergodic capacity of the SU fading channel. It is shown by simulations that the proposed Power Allocation strategies can achieve substantial capacity gain for the SU over that based on the conventional interference Power constraint, for the same PU outage probability loss.

  • Optimal Power Allocation for fading channels in cognitive radio networks ergodic capacity and outage capacity
    IEEE Transactions on Wireless Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Arumugam Nallanathan, H K Garg, Rui Zhang
    Abstract:

    A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) in a secondary communication network (SCN) to opportunistically operate in the frequency bands originally allocated to a primary communication network (PCN) or by allowing SCN to coexist with the primary users (PUs) in PCN as long as the interference caused by SCN to each PU is properly regulated. In this paper, we consider the latter case, known as spectrum sharing, and study the Optimal Power Allocation strategies to achieve the ergodic capacity and the outage capacity of the SU fading channel under different types of Power constraints and fading channel models. In particular, besides the interference Power constraint at PU, the transmit Power constraint of SU is also considered. Since the transmit Power and the interference Power can be limited either by a peak or an average constraint, various combinations of Power constraints are studied. It is shown that there is a capacity gain for SU under the average over the peak transmit/interference Power constraint. It is also shown that fading for the channel between SU transmitter and PU receiver is usually a beneficial factor for enhancing the SU channel capacities.

  • Optimal Power Allocation for fading channels in cognitive radio networks under transmit and interference Power constraints
    International Conference on Communications, 2008
    Co-Authors: Xin Kang, Yingchang Liang, Arumugam Nallanathan
    Abstract:

    In this paper, we study the Optimal Power control policies for fading channels in cognitive radio networks considering both the transmit and the interference Power constraints. For each of the constraints, the peak Power and the average Power are investigated. We derive the Optimal Power Allocation strategies in terms of maximizing the ergodic capacity of the secondary user when the channel state information is available to the transmitter and the receiver. It is shown that the Optimal Power adaption for each case has its own features, and is quite different from one to another. Finally, the numerical results are presented to validate the proposed Power Allocation methods for various Power constraint region.

H K Garg - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Power Allocation strategies for fading cognitive radio channels with primary user outage constraint
    IEEE Journal on Selected Areas in Communications, 2011
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a cognitive radio (CR) network where a secondary (cognitive) user shares the spectrum for transmission with a primary (non-cognitive) user over block-fading (BF) channels. It is assumed that the primary user has a constant-rate, constant-Power transmission, while the secondary user is able to adapt transmit Power and rate Allocation over different fading states based on the channel state information (CSI) of the CR network. We study a new type of constraint imposed over the secondary transmission to protect the primary user by limiting the maximum transmission outage probability of the primary user to be below a desired target. We derive the Optimal Power Allocation strategies for the secondary user to maximize its ergodic/outage capacity, under the average/peak transmit Power constraint along with the proposed primary user outage probability constraint. It is shown by simulations that the derived new Power Allocation strategies can achieve substantial capacity gains for the secondary user over the conventional methods based on the interference temperature (IT) constraint to protect the primary transmission, with the same resultant primary user outage probability.

  • Optimal Power Allocation for OFDM-based cognitive radio with new primary transmission protection criteria
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Xin Kang, Yingchang Liang, H K Garg, Rui Zhang
    Abstract:

    This paper considers a spectrum underlay network, where an OFDM-based cognitive radio (CR) system is allowed to share the subcarriers of an OFDMA-based primary system for simultaneous transmission. Instead of using the conventional interference Power constraint (IPC) to protect the primary users (PUs) in the primary system, a new criterion referred to as rate loss constraint (RLC), in the form of an upper bound on the maximum rate loss of each PU due to the CR transmission, is proposed for primary transmission protection. Assuming the channel state information (CSI) of the PU link, the CR link, and their mutual interference links is available to the CR, the Optimal Power Allocation strategy to maximize the achievable rate of the CR system is derived under RLC together with CR?s transmit Power constraint. It is shown that the CR system can achieve a significant rate gain under RLC as compared to IPC. Furthermore, the relationship between RLC and IPC is investigated, and it is shown that the rate gain is obtained by exploiting the additional CSI of the PU link. A more general case referred to as hybrid protection to PUs is then studied, by taking into account that some PU links? CSI is not available at CR.

  • Optimal Power Allocation for cognitive radio under primary user s outage loss constraint
    International Conference on Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Rui Zhang, H K Garg
    Abstract:

    In this paper, we consider a secondary link sharing the spectrum with a primary link in a fading cognitive radio (CR) network. Instead of applying the conventional interference Power constraint at the primary user (PU) receiver for the secondary user (SU) to protect the primary transmission, we propose a new constraint on the maximum tolerable outage probability for the PU due to the SU transmission. Under the assumption that perfect instantaneous channel state information (CSI) on the SU channel, the channel from the SU transmitter to PU receiver, and the PU channel is available at the SU transmitter, we derive the Optimal Power Allocation strategies to achieve the ergodic capacity of the SU fading channel. It is shown by simulations that the proposed Power Allocation strategies can achieve substantial capacity gain for the SU over that based on the conventional interference Power constraint, for the same PU outage probability loss.

  • Optimal Power Allocation for fading channels in cognitive radio networks ergodic capacity and outage capacity
    IEEE Transactions on Wireless Communications, 2009
    Co-Authors: Xin Kang, Yingchang Liang, Arumugam Nallanathan, H K Garg, Rui Zhang
    Abstract:

    A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) in a secondary communication network (SCN) to opportunistically operate in the frequency bands originally allocated to a primary communication network (PCN) or by allowing SCN to coexist with the primary users (PUs) in PCN as long as the interference caused by SCN to each PU is properly regulated. In this paper, we consider the latter case, known as spectrum sharing, and study the Optimal Power Allocation strategies to achieve the ergodic capacity and the outage capacity of the SU fading channel under different types of Power constraints and fading channel models. In particular, besides the interference Power constraint at PU, the transmit Power constraint of SU is also considered. Since the transmit Power and the interference Power can be limited either by a peak or an average constraint, various combinations of Power constraints are studied. It is shown that there is a capacity gain for SU under the average over the peak transmit/interference Power constraint. It is also shown that fading for the channel between SU transmitter and PU receiver is usually a beneficial factor for enhancing the SU channel capacities.