CDMA Cellular System: Advantages and Disadvantages

The CDMA cellular system offers a variety of advantages and disadvantages. Here, we’ll delve into the merits of CDMA:

• As the transmitted signal is spread across a wider bandwidth, the CDMA system is quite resilient against frequency-dependent problems such as fading and noisy bursts. This characteristic is known as frequency diversity.

• CDMA employs unique chipping codes for each user. These codes are designed to have low cross-correlation and low auto-correlation. Consequently, signals delayed by more than one chip period are less likely to interfere with the primary, dominant signal compared to other multipath environments. This makes CDMA resistant to the multipath effect.

• Privacy is a natural feature of CDMA systems. This is due to the use of unique codes for each mobile user.

• In FDMA and TDMA systems, the number of users that can access the system at the same time is limited and fixed. CDMA allows more users to access the system simultaneously, offering higher capacity.

Demerits (Disadvantages) of CDMA Cellular System

Now, let’s consider the downsides of CDMA:

• To ensure multiple users are aligned on chip boundaries, mobile users need to be synchronized. If users are not properly synchronized, the spreading sequences lose their orthogonality, and some degree of cross-correlation occurs.

• Signals originating closer to the base station experience less attenuation compared to signals from the farthest mobile subscribers. This difference in signal strength can make it difficult to recover transmissions from distant subscribers due to the incomplete orthogonality.

• Soft handoff in CDMA requires the mobile device to establish a connection with the new cell before releasing the connection with the old cell. This process is generally more complex than hard handoff procedures.