The Code Division Multiple Access (CDMA) technology was developed by Qualcomm, and has been operating in the United States since 1996. CDMA allows many users to share a common frequency/time channel for transmission. The user signals are distinguished by spreading them with different codes. In theory, this technology optimizes the utilization of the frequency bandwidth by equalizing signal-to-noise ratio (SNR) among all the users, thereby more equitably sharing the system power resources among them. While AMPS users who are near base stations typically enjoy SNRs (Signal to Noise Ratios) excess of 80dB. Users at the edge of cell coverage areas experience SNRs near the lower limit. With CDMA, users who are near base stations transmit less power maintaining the same SNR as users at the edge of a cells coverage.
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Showing posts with label GSM. Show all posts
Showing posts with label GSM. Show all posts
Sunday, October 13, 2013
What is MS (Mobile Station) ?
The MS (Mobile Station) consists of the physical equipment used by the subscriber to access a telecommunication services. Various types of MS, such as the vehicle mounted station, portable station, or handheld station are used. The mobile station (MS) consists of the mobile equipment (the terminal) and a smart card called the Subscriber Identity Module (SIM). The SIM provides personal mobility, so that the user can have access to subscribed services irrespective of a specific terminal. By inserting the SIM card into another GSM terminal (mobile phone), the user is able to receive calls at that terminal, make calls from that terminal, and receive other subscribed services.
What is SMS ?
SMS (Short Message Service) is a message service consisting of creating message of the size of a maximum of 160 alphanumeric characters. The message is sent to or from a mobile station. This can be considered as an advanced form of alphanumeric paging with a number of advantages. If the subscribers mobile unit is powered off or has left the coverage area, the message is stored and offered back to the subscriber when the mobile is powered on or has reentered the coverage area of the network. This ensures that the message will be received. Thus, SMS is a convenient facility of the GSM network.
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