Cross-layer reduction of wireless network card idle time to optimize energy consumption of pull thin client protocols

Thin client computing trades local processing for network bandwidth consumption by offloading application logic to remote servers. User input and display updates are exchanged between client and server through a thin client protocol. On wireless devices, the thin client protocol traffic can lead to a significantly higher power consumption of the radio interface. In this article, a cross-layer framework is presented that transitions the wireless network interface card (WNIC) to the energy-conserving sleep mode when no traffic from the server is expected. The approach is validated for different wireless channel conditions, such as path loss and available bandwidth, as well as for different network roundtrip time values. Using this cross-layer algorithm for sample scenario with a remote text editor, and through experiments based on actual user traces, a reduction of the WNIC energy consumption of up to 36.82% is obtained, without degrading the application's reactivity

Neighbor-friendly user scheduling algorithm for interference management in LTE-A networks

© 2015 IEEE. Downlink inter-cell interference is considered as a major challenge for cellular systems. For this purpose, the Long Term Evolution Advanced (LTE-A) standard uses soft frequency reuse (SFR), which assigns two fixed disjoint portions of the available bandwidth, one for center users and one for cell edge users. However, SFR forces the allocation of users in a certain portion of the bandwidth regardless of the users' channel conditions. Neighbor-friendly power control techniques have been studied as a means to reduce inter-cell interference in neighboring cells without forcing users to a certain bandwidth portion. Nevertheless, they are not directly applicable to LTE-A since the granularity of the power levels and the exchange of information between base stations are limited. In this paper, we use the principles of neighbor-friendly power control to develop a user scheduling algorithm that assigns physical resource blocks (PRBs) to users based on the channel quality indicator (CQI) and uses relative narrowband transmit power (RNTP) signalling to reallocate users whenever inter-cell interference is detected. Compared to the baseline algorithms, the proposed algorithm is able to increase the instantaneous CQI efficiency especially of cell edge users.status: publishe

An Algorithm for Cross-layer Subcarrier and Power Allocation in Cellular Networks

© 2015 EURASIP. Inter-cell interference is a major challenge in multi-user multi-carrier cellular networks, especially for cells with overlapping coverage. Several subcarrier and power allocation algorithms have been developed to deal with this problem. However, they focus on maximizing data rates using only physical layer information, disregarding upper layer information like the queue backlogs. Assigning subcarriers to the users based only on physical layer information like the channel conditions maximizes data rates, but may lead to network instability. To tackle this problem, we propose a cross-layer subcarrier and power allocation algorithm that uses physical layer information to reduce inter-cell interference and upper layer information to stabilize the network. Furthermore, our approach achieves a larger rate region than the baseline approach by protecting users in neighboring cells.status: publishe

MIMO Strategies for Energy Efficient Transmission in LTE Pico-cell Environments

trabalho apresentado em 20th International Conference on Software, Telecommunications and Computer Networks, 11-13 setembro 2012, Split, CroáciaMobile data traffic is increasing at an unprecedented rate. To cope with this, operators are deploying small base station sites to cover hot spots. However, this also increases the total network energy expenditure and carbon footprint. As a consequence, improving the energy efficiency of small base stations remains a hot topic. In this paper energy efficient transmission in LTE pico-cell environments is addressed aiming at providing a basis for LTE networks optimization and carbon footprint reduction. MIMO is studied from an energy efficiency point of view rather than from an increased datarates perspective as usually found in literature. Additionally, duty-cycling in time and frequency is also considered, hence, improving the amount of power reduction that can be achieved. Globally, a factor of twelve times variation between the worst-case power consumption and the optimally selected MIMO mode is observed in pico-cells.N/

Joint precoding vector and modulation and coding scheme recalculation for LTE-A multi-user MIMO

status: publishe

Neighbor-friendly autonomous power control in wireless heterogeneous networks

The widespread deployment of base stations constitutes a promising solution to cope with the ever-increasing wireless data rate demands. However, it also increases the interference levels, especially at the cell-edge. Most interference management techniques assume coordination between base stations, which involves undesired overhead and delays. To solve this problem, we propose a neighbor-friendly autonomous algorithm for power control in wireless heterogeneous networks that protects victim users from neighboring cells through a penalty factor in the power allocation level. We refer to this algorithm as neighbor-friendly iterative waterfilling (NF-IWF). In addition, we propose a low-complexity closed-form version that fixes the penalty factor by assuming a linear approximation of the victim user data rate. In high interference conditions, it can achieve a victim user data rate increase by a factor of 3.5 compared to IWF, 15 compared to soft frequency reuse (SFR), and 60 compared to equal power allocation (EPA) with a marginal decrease of the primary user data rate

Neighbor-friendly autonomous algorithm for power control in wireless heterogeneous Networks

© 2014, Torrea-Duran et al.; licensee Springer. The widespread deployment of base stations constitutes a promising solution to cope with the ever-increasing wireless data rate demands. However, it also increases the interference levels, especially at the cell-edge. Most interference management techniques assume coordination between base stations, which involves undesired overhead and delays. To solve this problem, we propose a neighbor-friendly autonomous algorithm for power control in wireless heterogeneous networks that protects victim users from neighboring cells through a penalty factor in the power allocation level. We refer to this algorithm as neighbor-friendly iterative waterfilling (NF-IWF). In addition, we propose a low-complexity closed-form version that fixes the penalty factor by assuming a linear approximation of the victim user data rate. In high interference conditions, it can achieve a victim user data rate increase by a factor of 3.5 compared to IWF, 15 compared to soft frequency reuse (SFR), and 60 compared to equal power allocation (EPA) with a marginal decrease of the primary user data rate.status: publishe

Exploiting the overhearing capabilities of transmitting nodes to increase the energy efficiency in dense networks

The 1000-fold capacity increase envisioned by dense 5G networks results also in a tremendous increase in the energy consumption of the whole network. Utilizing relays in combination with physical-layer network coding (PNC) has been proposed as an energy-efficient solution to this problem by creating several short-distance low-power transmissions and by reducing the transmission time. However, deploying relay nodes can be very costly for dense networks. On the other hand, the proximity of transmitting nodes in dense networks allows the transmitting nodes to serve as relays and retransmit the signals overheard from other transmitting nodes using PNC. This approach has been shown to increase the spectral efficiency, but the impact on energy efficiency has not been studied yet. Therefore, in this paper, we analyze two approaches that exploit the overhearing capabilities of the transmitting nodes in terms of spectral efficiency, energy efficiency, and success rate. We then provide a low-complexity power control strategy that achieves a performance close to the optimal for each approach. We show that when at least one indirect link is stronger than the direct links, exploiting the overhearing capabilities of the transmitting nodes provides the highest performance in both the transmit power-dominated and circuit power-dominated regimes

Exploiting the overhearing capabilities of transmitting nodes to increase the energy efficiency in dense networks

© 2017, The Author(s). The 1000-fold capacity increase envisioned by dense 5G networks results also in a tremendous increase in the energy consumption of the whole network. Utilizing relays in combination with physical-layer network coding (PNC) has been proposed as an energy-efficient solution to this problem by creating several short-distance low-power transmissions and by reducing the transmission time. However, deploying relay nodes can be very costly for dense networks. On the other hand, the proximity of transmitting nodes in dense networks allows the transmitting nodes to serve as relays and retransmit the signals overheard from other transmitting nodes using PNC. This approach has been shown to increase the spectral efficiency, but the impact on energy efficiency has not been studied yet. Therefore, in this paper, we analyze two approaches that exploit the overhearing capabilities of the transmitting nodes in terms of spectral efficiency, energy efficiency, and success rate. We then provide a low-complexity power control strategy that achieves a performance close to the optimal for each approach. We show that when at least one indirect link is stronger than the direct links, exploiting the overhearing capabilities of the transmitting nodes provides the highest performance in both the transmit power-dominated and circuit power-dominated regimes.status: publishe