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Learn CDMA Basics

Code Division Multiple Access (CDMA): Enabling Efficient Spectrum Sharing in Wireless Communications Posted on January 3, 2026 In the world of wireless communications, efficient use of the limited radio spectrum is crucial. One of the most powerful techniques for allowing multiple users to share the same frequency band simultaneously is Code Division Multiple Access (CDMA) . Unlike traditional methods that divide resources by frequency or time, CDMA uses unique codes to distinguish signals, making it a cornerstone of 3G mobile networks and influencing modern technologies like 4G and beyond. What is CDMA? CDMA is a multiple access technique based on spread-spectrum technology. In spread-spectrum systems, the signal is spread over a much wider bandwidth than necessary for the original data. This spreading is achieved by multiplying the data signal with a high-rate pseudorandom noise (PN) code, also known as a spreading code or chipping code. Key features of CDMA: ...
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Real-world applications of multiplexing and multiple access: From satellite communications to the Internet of Things

Multiplexing and multiple access are two important techniques that are used to improve the efficiency and capacity of communication systems. These techniques are used in many different fields and applications, from satellite communications to the Internet of Things (IoT).  In this post, we will explore some of the real-world applications of multiplexing and multiple access and the challenges and future developments in these areas. Satellite communications are one of the most important applications of multiplexing and multiple access. Satellites are used to provide communication services to remote and hard-to-reach areas, such as ships, airplanes, and remote locations.  Multiplexing and multiple access techniques are used to increase the capacity and efficiency of satellite communications. For example, frequency division multiplexing (FDM) is used to divide the available bandwidth into different frequency bands, and time division multiplexing (TDM) is used to divide the availab...
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Exploring the world of multiplexing and multiple access: How it improves communication efficiency

Communication is an essential part of our daily lives, and we rely on it for almost everything we do . From sending a text message to streaming a video , we use different communication systems to connect with the world . However, these systems are often limited by the amount of available bandwidth, which can cause congestion and delays. This is where multiplexing and multiple access come in . Multiplexing and multiple access are two techniques that are used to improve the efficiency and capacity of communication systems. In this post , we will explore what multiplexing and multiple access are, the different types of multiplexing and multiple access techniques, and how they are used in different communication systems. Multiplexing is a technique that allows multiple signals to share the same communication channel. It enables the simultaneous transmission of multiple signals over a single channel, which increases the capacity and efficiency of the c...
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Mobile Terminated Call in GSM

Mobile Terminated Call         • The calling party dials the MSISDN for the mobile subscriber. • The PSTN identifies the network (PLMN) that the dialed MSISDN belongs to and will locate a GMSC for that network.         • The PSTN sends an Initial Address message to the GMSC. •T he GMSC forwards the MSISDN to the HLR and requests routing information for it. • The HLR looks up the MSISDN and determines the IMSI and the SS7 address for the MSC/VLR that is servicing the MS. •T he HLR then contacts the servicing MSC/VLR and asks it to assign a Mobile Station Routing Number (MSRN) to the call. (a MSRN is assigned to the call not to the MS itself. ) • The MSC/VLR allocates the MSRN and forwards it to the HLR.
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Call Setup GSM Flow

GSM Call Flow (GSM Originating Call) Call Setup GSM Flow Call Setup GSM Flow: •              The MSC sends an Initial Address Message (IAM) to the GMSC. The IAM contains the MSISDN of the called party as the MS dialed it. •              The MSC will also send a Call Proceeding (CALL_PROC) message down to the BSS and this is when the BSS would assign a TCH to the MS, as described earlier •              Based on the dialed number, the GMSC decides where to route the IAM within the PSTN. •              The PSTN will continue to route the IAM until it reaches the correct Switching Center and the call routing is complete. The PSTN will then establish the call circuit and send an Address Complete Message (ACM) back to the GMSC. •              The GMSC then forwards the ACM back to the r...
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What is Ray Model?

Introduction Ray Model 1. Optical fiber is basically a solid glass rod. The diameter of rod is so small that it looks like a fiber. 2. Optical fiber is a dielectric waveguide. The light travels like an electromagnetic wave inside the waveguide. The dielectric waveguide is different from a metallic waveguide which is used at microwave and millimeter wave frequencies. 3. In a metallic waveguide, there is a complete shielding of electromagnetic radiation but in an optical fiber the electromagnetic radiation is not just confined inside the fiber but also extends outside the fiber. 4. The light gets guided inside the structure, through the basic phenomenon of total internal reflection . 5. The optical fiber consists of two concentric cylinders; the inside solid cylinder is called the core and the surrounding 6. For the light to propagate inside the fiber through total internal reflections at core-cladding interface, the refractive index of the core must be greater tha...
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BROADBAND COMMUNICATION IMPORTANT QUESTIONS

BROADBAND COMMUNICATION QUESTION BANK 1.  (a)           What are the advantages of optical fiber cables over the co-axial cables?     (06) (b) Calculate NA, Acceptance angle and Angle of fiber with core and cladding refractive index values as n 1 =1.5 and n 2 =1.45 respectively.                                                                    (06) (c) Explain the “mode theory” of optical fiber.     (06) 2.  (a)           What is meant by accepta...
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