Impact of LOS/NLOS Propagation on the Coverage Performance of Multi-Stream MIMO-ZFBF Cellular Downlink

IEEE Trans. Veh. Technol.

Leung

2019

Self Cite

For a low-mobile Poisson bipolar network and under line-of-sight/non-line-of-sight (LOS/NLOS) path-loss model, we study repetitive retransmissions (RR) and blocked incremental redundancy (B-IR). We consider spatially-coded multiple-input multiple-output (MIMO) zero-forcing beamforming (ZFBF) multiplexing system, whereby the packet success reception is determined based on the aggregate data rate across spatial dimensions of the MIMO system. Characterization of retransmisimportant, but inherently complex due to a substantial rate correlation across retransmissions and intractability of evaluating the probability density function (pdf) of aggregate data rate.results show that, compared to RR scheme, B-IR scheme has higher RCC while its coverage probability is substantially larger. We demonstrate that the spotted contention between coverage probability and RCC causes the mean transmission delay (MTD) of B-IR to become either smaller or larger than the MTD of RR scheme. Finally, we develop a numerical approximation of MTD, and evaluate the effective spatial throughput (EST), which is reciprocal to MTD, of RR and B-IR schemes. Our numerical multiplexing gain, block length, and activity factor of nodes. We further observe that for dense networks 1) LOS component is considerably instrumental to enhance EST; 2) EST of B-IR scheme can be much higher than that of RR scheme; 3) When Doppler spread exists, it can improve MTD of B-IR while it does not cast any meaningful effect on the MTD of RR.

Section: A Mtdsupporting

confidence: 82%

“…NLOS) link. According to 3GPP path-loss model [16,34], we then specify path-loss function through the following probabilistic form [17,33]:…”

Section: A Network Model and Main Assumptionsmentioning

confidence: 99%

Section: Performance Evaluationmentioning

confidence: 99%

“…Now we use approximations (34) and (33) to evaluate the ETS of RR and B-IR schemes, respectively. In Fig.…”

Section: B Estmentioning

confidence: 99%

See 2 more Smart Citations

Delay Analysis of Spatially Coded MIMO-ZFBF With Retransmissions in Random Networks

IEEE Trans. Veh. Technol.

Leung

2019

Self Cite

“…Randomized content placement is extended further in [10], [11] to -tier HetNets, where the probability of content placement stays the same across the BSs in each tier. The optimal probabilistic content placement is shown in [10], [11] Nevertheless, the above studies fail to incorporate the following two important practical aspects of the HetNets in caching performance analysis: (i) Although the cost of installing caching equipments (memory and the corresponding hardware) is much lower than that of the backhaul's for a dense/ultra-dense network, such as in 5G [1], the aggregated cost of caching may exceed the backhaul's cost; (ii) interference as many UEs might receive interferences from a large number of BSs through a line-of-sight (LOS) channel [12], [13].…”

Section: Introductionmentioning

confidence: 99%

Caching or No Caching in Dense HetNets?

2019 IEEE Wireless Communications and Networking Conference (WCNC)

Navaie

Shin

et al. 2019

Caching the content closer to the user equipments (UEs) in heterogenous cellular networks (HetNets) improves user-perceived Quality-of-Service (QoS) while lowering the operators backhaul usage/costs. Nevertheless, under the current is unclear whether cache-enabled HetNets preserve the claimed the collective cost of caching which may inevitably exceed the expensive cost of backhaul in a dense HetNet, and 2) the excessive interference which affects the signal reception irrespective of it simultaneously reduces cache-hit probability and increases the only about of the content library size in the cache of smallcell base stations. Furthermore, we show that range expansion, which is known to be of substantial value in wireless networks, from macro cells to small cells, in cache-enabled HetNets, it is do the opposite.

Coverage Performance in MIMO-ZFBF Dense HetNets with Multiplexing and LOS/NLOS Path-Loss Attenuation

IEEE Trans. on Mobile Comput.

Navaie

Shin

et al. 2020

Self Cite

The performance of multiple-input multiple-output (MIMO) multiplexing heterogenous cellular networks are often analyzed using a single-exponent path-loss model. Thus, the effect of the expected line-of-sight (LOS) propagation in densified settings is unaccounted for, leading to inaccurate performance evaluation and/or inefficient system design. This is due to the complexity of LOS/non-LOS models in the context of MIMO communications. We address this issue by developing an analytical framework based on stochastic geometry to evaluate the coverage performance. We focus on the zero-forcing beamforming where the maximum signal-to-interference ratio is used for cell association. We analytically derive the coverage. We then investigate the cross-stream interference correlation, and develop two approximations of the coverage: Alzer Approximation (A-A) and Gamma Approximation (G-A). The former is often used in the single antenna and single-stream MIMO. We extend A-A to a MIMO multiplexing system and evaluate its utility. We show that the inverse interference is well-fitted by a Gamma random variable, where its parameters are directly related to the system parameters. The accuracy and robustness of G-A is higher than that of A-A. We observe that depending on the multiplexing gain, it is possible to attain the best coverage probability by proper densification.