Orthogonal frequency division multiple access (OFDMA): Mobile WiMAX uses OFDM as a multiple-access technique, whereby different users can be allocated different subsets of the OFDM tones. As discussed in detail in Chapter 6, OFDMA facilitates the exploitation of frequency diversity and multiuser diversity to significantly improve the system capacity. Flexible and dynamic per user resource … Read more
The challenge to broadband wireless comes from the scarcity of radio-spectrum resources. Regulatory bodies around the world have allocated only a limited amount of spectrum for commercial use. The need to accommodate an ever-increasing number of users and offering bandwidth-rich applications using a limited spectrum challenges the system designer to continuously search for solutions that … Read more
Applications using a fixed wireless solution can be classified as point-to-point or point-to-multipoint. Point-to-point applications include interbuilding connectivity within a campus and microwave backhaul. Point-to-multipoint applications include broadband for residential, small office/home office (SOHO), and small- to medium-enterprise (SME) markets, T1 or fractional T1-like services to businesses, and (3) wireless backhaul for Wi-Fi hotspots. Consumer … Read more
Here I list out some important OFDM characters for Wimax. Let’s check it in detail. OFDM Pros and Cons: OFDM enjoys several advantages over other solutions for high-speed transmission. Reduced computational complexity: OFDM can be easily implemented using FFT/IFFT and the processing requirements grow only slightly faster than linearly with data rate or bandwidth The … Read more
Angular Spread and Coherence Distance calculation for Wimax Calculation Angular Spread and Coherence Distance is very easy let’s see. So far, we have focused on how the channel response varies over time and how to quantify its delay and correlation properties. However, channels also vary over space. We do not attempt to rigorously treat all … Read more
Which OFDM Parameters Used in WiMAX The fixed and mobile versions of WiMAX have slightly different implementations of the OFDM physical layer. Fixed WiMAX, which is based on IEEE 802.16-2004, uses a 256 FFT-based OFDM physical layer. Mobile WiMAX, which is based on the IEEE 802.16e-20055 standard, uses a scalable OFDMA-based physical layer. In the … Read more
Slow Fading Margin in LTE with example of standard deviations in slow fading Shadow fading indicates the fading brought by obstruction due to a building or a natural feature. Shadow fading changes slowly, and is thus called “slow fading”. Statistics repeatedly show that the median levels of received signals follow log-normal distribution with the time … Read more
Visualization of Beam Forming in LTE Currently, beam forming is only applicable for TDD version of LTE. The time synchronous version of LTE TDD on uplink and downlink also makes the implementation of beam forming more attractive than in LTE FDD. Beam forming scheme is a signal processing technology that is used to direct radio … Read more
What and How Cell Edge Rate in LTE Cell Edge Rate in LTE is simple if it’s High then Coverage Low and if It’s Low then Coverage high similar to Frequency selection. Not clear lets understand in detail. Cell Edge Rate in LTE Similar to other wireless communications systems, such as CDMA2000 EVDO, WiMAX and … Read more
Definition of LTE Interference Margin Here I write Interference Margin in simple word and basic definition of interference margin in LTE. Let understands it. Interference margin accounts for the increase in the terminal noise level caused by the interference from other users. LTE uplink is orthogonal if it is within the same cell so there … Read more