Effective Overloaded Pilot Assignment with Pilot Decontamination for Cell-Free Systems

Osawa, Noboru; Göttsch, Fabian; Ohseki, Takeo; Amano, Yoshiharu; Yamazaki, Kosuke; Caire, Giuseppe

doi:10.48550/arxiv.2207.11478

Cited by 1 publication

(1 citation statement)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The solution is immediate and consists of sorting the users in decreasing order of the product Q k ptq Rk and letting Aptq the set of the top K act sorted users. Given the selected set Aptq, UL pilots and user-centric clusters are assigned to the active UEs following the semi-overloaded pilot assignment method from [20], where an RU may assign the same pilot sequence to multiple UEs provided that the channel subspaces of the UEs are nearly mutually orthogonal, such that accurate channel estimation is possible (negligible mutual pilot contamination, using the decontamination method of [7]). An RU-UE association can only be established, when the SNR association threshold criterion β ,k ě η M SNR is fulfilled, where η is an association threshold parameter.…”

Section: A Pilot and Cluster Reallocation Schemementioning

confidence: 99%

Fairness Scheduling in Dense User-Centric Cell-Free Massive MIMO Networks

Göttsch

Osawa

Ohseki

et al. 2022

2022 56th Asilomar Conference on Signals, Systems, and Computers

Self Cite

View full text Add to dashboard Cite

We consider fairness scheduling in a user-centric cell-free massive MIMO network, where L remote radio units, each with M antennas, serve K « LM user equipments (UEs). Recent results show that the maximum network sum throughput is achieved where Kact « LM 2 UEs are simultaneously active in any given time-frequency slots. However, the number of users K in the network is usually much larger. This requires that users are scheduled over the time-frequency resource and achieve a certain throughput rate as an average over the slots. We impose throughput fairness among UEs with a scheduling approach aiming to maximize a concave component-wise non-decreasing network utility function of the per-user throughput rates. In cell-free user-centric networks, the pilot and cluster assignment is usually done for a given set of active users. Combined with fairness scheduling, this requires pilot and cluster reassignment at each scheduling slot, involving an enormous overhead of control signaling exchange between network entities. We propose a fixed pilot and cluster assignment scheme (independent of the scheduling decisions), which outperforms the baseline method in terms of UE throughput, while requiring much less control information exchange between network entities.

show abstract

Section: A Pilot and Cluster Reallocation Schemementioning

confidence: 99%