arXiv subjects

Homa Nikbakht

Publications and source records attributed to Homa Nikbakht.

23 records · Page 2Linked to original sources

arXiv2019

Multiplexing Gain Region of Sectorized Cellular Networks with Mixed Delay Constraints

The sectorized hexagonal model with mixed delay constraints is considered when both neighbouring mobile users and base stations can cooperate over rate-limited links. Each message is a combination of independent "fast" and "slow" bits, where the former are subject to a stringent delay constraint and cannot profit from cooperation. Inner and outer bounds on the multiplexing gain region are derived. The obtained results show that for small cooperation prelogs or moderate "fast" multiplexing gains, the overall performance (sum multiplexing gain) is hardly decreased by the stringent delay constraints on the "fast" bits. For large cooperation prelogs and large "fast" multiplexing gains, increasing the "fast" multiplexing gain by $Δ$ comes at the expense of decreasing the sum multiplexing gain by $3 Δ$.

cs.IT↗

arXiv2018

Mixed Delay Constraints in Wyner's Soft-Handoff Network

Wyner's soft-handoff network with mixed delay constraints is considered when neighbouring receivers can cooperate over rate-limited links. Each source message is a combination of independent "fast" and "slow" bits, where the former are subject to a stringent decoding delay. Inner and outer bounds on the capacity region are derived, and the multiplexing gain region is characterized when only transmitters or only receivers cooperate.

cs.IT↗

arXiv2016

Exact Throughput Analysis of Random CoopMAC Networks in the Presence of Shadowing

The throughput performance of a random cooperative medium access control (CoopMAC) network in the presence of shadowing is considered. The nodes are assumed to be randomly distributed according to a homogeneous two-dimensional Poisson point process with constant intensity. The conditions under which a helper can improve the transmission rate between a given pair of nodes are examined. Based on these conditions, an exact analytical expression is derived for the average cooperative throughput of a random CoopMAC network that is subject to path loss and shadowing. This expression is then used to investigate the effects of shadowing, intensity of nodes and the distance between source and destination nodes on the cooperative throughput of the network. It is observed that the average cooperative throughput of the network increases only slightly when the intensity of helpers increases beyond a certain value.

cs.NI↗

arXiv2016

Joint Throughput Maximization and Power Control in Poisson CoopMAC Networks

A cooperative medium access control (CoopMAC) network with randomly distributed helpers is considered. We introduce a new helper selection scheme which maximizes the average throughput while maintaining a low power consumption profile in the network. To this end, all transmissions are assumed to be performed using power control. We assume that each node can estimate the channel between itself and a receiving node. Then, it evaluates the minimum transmission power needed to achieve the desired signal to noise ratio (SNR). If the required transmission power is less than the maximum transmission power of the node, the communication is regarded as successful. Otherwise, the transmission is canceled. %Also, we classify the helpers into six groups according to their transmission rates IEEE 802.11b Standard. In order to increase the average throughput, we assume that the cooperative link with the highest transmission rate is chosen from those that can successfully forward the source signal to destination. Also, when there are several links with the same rates, the one with minimum required power is given the highest priority. Assuming that the helpers are distributed as a Poisson point process with fixed intensity, we derive exact expressions for the average throughput and the power consumption of the network. Simulation results show that our scheme is able to significantly increase the throughput in comparison to the conventional CoopMAC network. It is also able to reduce the power consumption compared to a network with no power control approach.

cs.NI↗

arXiv2016

A New Approach for Helper Selection and Performance Analysis in Poisson CoopMAC Networks

The cooperative medium access control (CoopMAC) protocol in the presence of randomly-distributed nodes and shadowing is considered. The nodes are assumed to be distributed according to a homogeneous two-dimensional Poisson point process. A new approach is proposed for helper selection and throughput performance analysis which depends on the shadowing parameters as well as the distribution of helpers. In the proposed protocol, the potential helpers are divided into several tiers based on their distances from the source and destination in a way that the lower the tier index, the higher its priority. When there are several helpers of the same tier, the helper that is less affected by shadowing is chosen for cooperation. Upper and lower bounds are derived for the average cooperative throughput of the proposed CoopMAC protocol. It is observed that the proposed scheme readily outperforms the conventional CoopMAC protocol in having larger average throughput. It is also seen that the cooperative throughput of the proposed scheme approaches the upper bound when the density of nodes increases.

cs.NI↗