OFDMA is essentially a hybrid of FDMA and TDMA: Users are dynamically assigned subcarriers (FDMA) in different time slots (TDMA) . The advantages of OFDMA start with the advantages of single-user OFDM in terms of robust multipath suppression and frequency diversity. In addition, OFDMA is a flexible multiple-access technique that can accommodate many users with … Read more
The Difference Between Line Of Sight and Non-Line Of Sight Line of Sight (LOS): In LOS communication, there is a direct, unobstructed path between the transmitter and receiver. This type of communication is typically more reliable and offers higher data transfer rates because there are minimal obstacles in the signal’s path. LOS is commonly used … Read more
Fixed WiMAX offers cost effective point to point and point to multipoint solutions. What makes WiMAX so exciting is the broad range of applications it makes possible but not limited to broadband internet access, T1/E1 substitute for businesses, voice over Internet protocol (VoIP) as telephone company substitute, Internet Protocol Television (IPTV) as cable TV substitute, … Read more
How does WiMAX compare with the existing and emerging capabilities of 3G and Wi-Fi? The throughput capabilities of WiMAX depend on the channel bandwidth used. Unlike 3G systems, which have a fixed channel bandwidth, WiMAX defines a selectable channel bandwidth from 1.25MHz to 20MHz, which allows for a very flexible deployment. When deployed using the … Read more
Naturally, the first application for which a wireless alternative was developed and deployed was voice telephony. These systems, called wireless local-loop (WLL), were quite successful in developing countries such as China, India, Indonesia, Brazil, and Russia, whose high demand for basic telephone services could not be served using existing infrastructure. In fact, WLL systems based … Read more
In LTE (Long-Term Evolution), handover measurements are crucial for ensuring seamless mobility as User Equipment (UE) moves across different cells within the network. These measurements assist in deciding when and to which cell a handover should occur. Here’s an overview of key handover measurements in LTE: Received Signal Strength (RSS): RSS measures the power level … Read more
Reverse power control Open loop power control Closed loop power control Inner loop power control: 800 Hz Outer loop power control Forward power control Message transmission mode: threshold transmission periodic transmission Closed loop power control Reverse open loop power control means that based on the detected signals from a base station, a mobile station … Read more
The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the forward CDMA channel Control the insertion of power control bit Spread the information on the reverse CDMA channel to identify the mobile stations In a reverse direction, different long codes are used for the information … Read more
It can be seen from the figure that the data are read row by row into an interleaver at the transmit end,read column by column out (this process is called interleaving) and propagated after other modulation process. Then, the data enter the interleaver at the receive end row by row and are read out column … Read more
The UE is RRC connected.During the HO:The radio link is released from the eNodeB 1 and re-established on the eNodeB 2The Control plane is switched to the eNodeB 2 and the MMEThe User plane is switched to the eNodeB 2 and the S-GW The Intra-e-UTRAN-Access Mobility Support for UEs in ECM-CONNECTED handles all necessary steps … Read more