Abstract
A piece of user equipment (UE), typically, has access to multiple radio access technologies (RATS). Moreover, apart from the standard primary cellular network, the secondary cellular networks can assist the primary network in downlink UE communications. In this way, the data can reach the UE through multiple entities. This paper exploits the multiple entities’ idea by proposing a cross-layer scheme that combines data to improve the block error rate (BLER) and the throughput. For this, we define a new entity, called the super-MAC, just above the Medium Access Control (MAC) layer. More specifically, we propose data duplication (at the transmitter) and combining (at UE) at the super-MAC, where the super-MAC gets the Radio Link Layer protocol data unit (RLC-PDU) and sends multiple-copies across various interfaces to different MAC-entities. In doing so, the super-MAC attaches a unique sequence number to a group of RLC-PDUs together. At the UE, the data from different MAC entities are combined at super-MAC to clear any block error. The super-MAC operates in between the Cyclic Redundancy Check and Forward Error Correction stages of the HARQ process. The additional complexity introduced by the scheme is negligible in front of the existing operations. Moreover, the average latency improves due to the significant improvement in the Block Error rate (BLER) that the combining scheme offers over the BLER of the conventional standalone system. Also, since the errors significantly reduce, the throughput shows significant improvement. Finally, the proposed scheme is an advancement in HARQ to reduce retransmissions, and hence it is suitable for the next-generation networks like B5G or 6G to adopt the super-MAC.
Highlights
With an increase in the number of users, there has been an exponential increase in demand for data, which has caused tremendous pressure on the current cellular networks like 4GLTE and non-standalone 5G-NR
We show that combining at the super-Medium Access Control (MAC) is superior to PDCP based approach in terms of block error rate (BLER) and throughput
Using an example of 4G-LTE as primary MAC (PMAC), and 5G-NR and IEEE 802.11ac WiFi as SMACS, we show a wide range of compatible rates exists that allow WiFi to work with LTE and 5G-NR to work with LTE
Summary
With an increase in the number of users, there has been an exponential increase in demand for data, which has caused tremendous pressure on the current cellular networks like 4GLTE and non-standalone 5G-NR. Ahmed et al.: Super-MAC: Data Duplication and Combining for Reliability Enhancements Such approaches are suggested for the 5G-NR (NR-U) [12]–[14]. We propose data duplication and combining schemes at a newly defined entity, super-MAC. The super-MAC supplies essential information like the addresses of the source and destination, among other things Note that this sequence number is different from the sequence number assigned at the PDCP and the RLC layers. If any path declares an error-free block’s reception, it reports the sequence number of this block to the primary MAC (PMAC) and the PMAC sends the error-free data to the RLC layer.
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