Combined Bank Assistant Maintenance Engineer/ Assistant Hardware Engineer Exam: 23.11.2023 (BIBM)প্রশ্ন ও সমাধান

Answer: Multiplexing combines several signals to travel over one shared physical medium, using a multiplexer (MUX) to combine and a demultiplexer (DEMUX) to separate them at the receiving end. There are four main types:

1. FDM (Frequency Division Multiplexing): the channel's total bandwidth is divided into separate, non-overlapping frequency bands, one per signal — all transmitted simultaneously. Used in radio/TV broadcasting and analog cable systems.

2. TDM (Time Division Multiplexing): each signal gets the entire channel bandwidth, but only for a short, recurring time slot, in round-robin fashion.

• Synchronous TDM: fixed time slots assigned regardless of whether a source has data ready.
• Statistical/Asynchronous TDM: slots allocated dynamically only to sources with data, improving efficiency.

3. WDM (Wavelength Division Multiplexing): used specifically on fiber-optic cable — multiple signals travel as different wavelengths (colors) of light on the same fiber simultaneously.

4. CDM (Code Division Multiplexing): each signal is encoded with a unique spreading code so all signals can share the same time and frequency, separated purely by their code at the receiver — the basis of CDMA mobile networks.

graph TD
    M[Multiplexing] --> F["FDM - by frequency band"]
    M --> T["TDM - by time slot"]
    M --> W["WDM - by light wavelength, fiber only"]
    M --> C["CDM - by unique code"]

Exam takeaway: FDM splits by frequency, TDM splits by time, WDM splits by wavelength (fiber-optic specific), CDM splits by code — all let multiple signals share one physical link efficiently.

Answer: Digital banking delivers banking services (account access, transfers, payments, loans) through online/mobile digital channels, rather than requiring a customer to visit a physical branch.

Aspect	Traditional Banking	Digital Banking
Access	Branch visit, limited hours	24/7, from anywhere with internet
Channel	Face-to-face at a counter	Website, mobile app, ATM/agent network
Transaction speed	Slower (manual processing)	Near real-time
Paperwork	Physical forms, signatures	Digital forms, e-KYC, OTP verification
Cost to serve	Higher (branch staff/infrastructure)	Lower (automated, scalable)

How digital banking promotes financial inclusion:

• Removes geographic barriers: mobile banking (e.g., bKash, Nagad in Bangladesh) reaches rural populations with no nearby bank branch.
• Lowers the cost of service: no need to maintain expensive branch infrastructure to serve low-balance customers, making small accounts viable for banks.
• Simplified onboarding: agent banking and e-KYC let unbanked people open accounts with minimal documentation.
• Micro-transactions/micro-loans: digital platforms make small-value transfers, savings, and microcredit economically feasible for low-income and informal-sector workers.

graph LR
    U[Unbanked Rural Customer] --> M[Mobile/Agent Banking App]
    M --> B[Bank's Digital Core System]
    B --> S[Savings, Payments, Microloans]

Exam takeaway: digital banking = branch-independent, 24/7, low-cost service delivery; its scalability and reduced onboarding friction are precisely what extend formal financial services to previously unbanked/underbanked populations.