# Multi-Connectivity-Based Adaptive Fractional Packet Duplication in Cellular Networks
###### Abstract  
Mobile networks of the fifth generation have stringent requirements for data throughput, latency and reliability. Dual or multi-connectivity is implemented to meet the mobility requirements for certain essential 5G use cases, and this ensures the user's connection to one or more radio links. Packet duplication (PD) over multi-connectivity is a method of compensating for lost packets by reducing re-transmissions on the same erroneous wireless channel. Utilizing two or more uncorrelated links, a high degree of availability can be attained with this strategy. However, complete packet duplication is inefficient and frequently unnecessary. The wireless channel conditions can change frequently and not allow for a PD. We provide a novel adaptive fractional packet duplication (A-FPD) mechanism for enabling and disabling packet duplication based on a variety of parameters. The signal-to-interference-plus-noise ratio (SINR) and fade duration outage probability (FDOP) are important performance indicators for wireless networks and are used to evaluate and contrast several packet duplication scenarios. Using ns-3 and MATLAB, we present our simulation results for the multi-connectivity and proposed A-FPD schemes. Our technique merely duplicates enough packets across multiple connections to meet the outage criteria.  
fade duration outage probability (FDOP); average fade duration (AFD); adaptive-fractional packet duplication (A-FPD); carrier aggregation; dual connectivity; multi-connectivity +
Footnote †: journal: _Acticle_  
In order to overcome the propagation pathloss, highly directional means of communication are implemented. Appreciating the small wavelength of the mmWave, many antennas can be packed closely together to enable massive multiple input multiple output (mMIMO) diversity that, in turn, improves the link budget and range of the communication. In order to tackle the other challenge of blockage, ultra dense network (UDN) deployment is a method used to deploy more small cells reducing shadowing or no-coverage zones.  
Our main goal is to design a mechanism to automatically turn packet duplication ON and OFF based off the wireless channel conditions. This is keeping in mind the trade off between the signaling required and the overall system throughput. In order to reduce the signaling overhead, we take an average of the instantaneous SINR over a certain sample size that will be consistent with the channel conditions. The major contributions of this paper are as follows:  
* Utilize the available SINR as a key performance indicator to design multiple packet duplication schemes for making them more adaptive to near real time wireless channel and environmental conditions.
* Use fade duration outage probability (FDOP), in addition to SINR, to improve the network connectivity, reliability and low latency with adaptive fractional packet duplication (A-FPD).
* Attain high degree of availability using two or more uncorrelated links and only duplicate packets efficiently to not over-utilize the limited radio resources applying the proposed adaptive fractional packet duplication (A-FPD) schemes.