Performance of Dynamic Time Division Broadcast Protocol with Rateless Coding

Two-way relaying channel (TWRC) improves the throughput of one-way relaying channel through network coding at the relay. Time division broadcast (TDBC) is one typical protocol for TWRC, but with three time slots for one round information exchange leading to throughput loss. To enhance throughput performance, incremental redundancy transmission is usually incorporated into TDBC (i.e., TDBC-IR) by one bit feedback, indicating the successful or failed transmission. Nevertheless, TDBC-IR still suffers in throughput since it cannot fully exploit and adapt to the varying channel dynamics. In the paper, we propose a dynamic TDBC protocol with incremental redundancy in the form of rateless coding (i.e., DTDBC-RC) to fully utilizing the varying channel dynamics. In DTDBC-RC, the two sources first transmit in rateless coding way with given maximum allowable transmission time, and then the relay retransmits or not based on its decoding results. To reveal the advantages of DTDBC-RC, we analyze its performance comprehensively in terms of outage probability, expected rate, and diversity-multiplexing trade-off (DMT). We also present a subslot realization scheme for DTDBC-RC (i.e., sub-DTDBC-RC) since the DMT of DTDBC-RC cannot be obtained directly. Simulation and numerical results show the performance advantage of DTDBC-RC (or sub-DTDBC-RC) over TDBC-IR in terms of both expected rate and DMT.

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Centralized Dynamic-Time Division Duplex Utilizing Interference Alignment

IEEE Transactions on Wireless Communications ◽

10.1109/twc.2021.3077250 ◽

2021 ◽

pp. 1-1

Author(s):

Mojtaba Ghermezcheshmeh ◽

Mohsen Mohammadkhani Razlighi ◽

Vahid Shah-Mansouri ◽

Nikola Zlatanov

Keyword(s):

Interference Alignment ◽

Time Division Duplex ◽

Dynamic Time ◽

Time Division

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Impact of Competition on Efficiency of Microfinance Institutions: Cross Country Comparison of India and Bangladesh

International Journal of Rural Management ◽

10.1177/09730052211005244 ◽

2021 ◽

pp. 097300522110052

Author(s):

Joyeeta Deb ◽

Ram Pratap Sinha

Keyword(s):

Information Exchange ◽

Data Envelopment ◽

Bottom Of The Pyramid ◽

Microfinance Institutions ◽

Tobit Regression ◽

Social Efficiency ◽

Trade Off ◽

Social Objective ◽

Efficient Level ◽

Potential Impact

Increased competition coupled with commercialisation in the Indian microfinance sector has brought about many major transformations. From an impact-driven development programme, microfinance institutions (MFIs) today emerged as commercially oriented profit-making entities. In addition to bringing their commercial and social objectives into balance, MFIs today are striving for efficient level of operation. Efficiency in the level of operation of MFIs allows them to remain competitive and attain financial sustainability. However, it is also imperative for MFIs to remain socially committed towards the ultimate mission of reaching the poorest at the bottom of the pyramid. Hence, it is of research interest to see the trade-off between MFIs’ social objective of spreading outreach and at the same time remaining financially sustainable. Against this backdrop, this article is devoted to study the potential impact of competition and commercialisation on efficiency of MFIs in India and Bangladesh. The study is carried over 75 MFIs altogether over the period of 8 years from 2009 to 2016. The data have been collected from microfinance information exchange database. Efficiency is measured through technical efficiency (TE) scores as estimated under data envelopment analysis. In order to establish the association between competitions, which is estimated by the Herfindahl–Hirschman index (HHI), tobit regression is used. The study evidenced increasing level of competition in the sector over the years, but it is more pronounced in India as against Bangladesh. In order to analyse the trade-off, TE scores are separately estimated under both financial and social measures. TE score is found to be higher in case of social measures of efficiency as against financial efficiency. Further, under both the measures, competition is found to be having a significant impact on both financial and social efficiency.

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