Bandwidth required to transmit a signal or bandwidth of a transmission media plays an important role in any form of communication (wired or wireless). This paper explains the importance of bandwidth and how we can choose modulation technique, multiple access technique and other parameters for broadband communication so that the available bandwidth gets enhanced. The paper compares the majorly used analog to digital encoding technique Delta Modulation (DM) with Pulse Code Modulation (PCM) in terms of required bandwidth for number of users (channels). It was found that DM is better. The probability of error is an important parameter to fix channel capacity. In the analysis, it was found that probability of error for Binary Phase Shift Keying (BPSK) and Orthogonal Frequency-Division Multiplexing (OFDM) is better than Quadrature Phase Shift Keying (QPSK) and Direct Sequence (DS)-Code Division Multiple Access (CDMA) respectively. We can efficiently utilize bandwidth by selecting bandwidth-efficient analog to digital encoding methods like DM and BPSK as modulation techniques, and OFDM-CDMA as multiple access technique with digital equipments.

In olden days 90% communication was by voice and only 10% was by data, but now with the advent of Internet, the situation is just opposite—only 10% communication is by voice and 90% is by data. Future mobile communication systems will provide not only voice and low speed data services, but also video and high-speed data services. Furthermore, the system will have the capability for wireless multimedia communications. To support those services, the system should guarantee higher data transmission capacity at a radio interface and higher data rate for each user up to several megabits per second (Dong et al., 1998). Every transmission medium has a fixed bandwidth. The rate at which data can be transmitted over a given communication path or channel under given conditions is referred to as the channel capacity (William, 2001). There are many factors which affect the channel capacity of a system like data rate, bandwidth, noise and error rate. Signal fading due to multipath propagation is a dominant source of impairment in wireless communication system (Zhao et al., 2005), .

causing high Bit Error Rate (BER). For high capacity data rate, bandwidth of transmission media should be high, and noise level, error rate and required bandwidth of transmitted signal should be less. The channel capacity is fixed by considering all the above parameters for successful communication.

Telecommunications Journal, Speech Noise Elimination, Traditional Spectrum Subtraction, Communication Systems, Speech Processing Algorithms, Signal Processing, Noise Reduction Techniques, Voice Activity Detection, Spectrum Subtraction Method, Signal to Noise Ratios, Cockpit Voice Recorder, Musical Noise.