hannel time variations. On the other hand, for large values of T max (i.e., large delay spread, or alternatively small coherence bandwidth means that channel is frequency- selective), m should be small to closely follow channel frequency variation. In a regularly spaced pilot pattern, the pilot symbols are evenly spaced in frequency and in time. Cell-specific reference signals (CRS) were originally defined in 3GPP LTE Rel-8 and have continued to be used as downlink wideband always-on power-boosted pilot subcarriers which are scaled with the number of transmit antenna ports that are essential in coherent decoding/detection of the LTE downlink control channels, mobility measurements, etc. The always-on and power-boosted properties of CRS have been the potential cause of inter-cell interference in LTE networks even in the absence of user traffic. The reference signals in NR are different from LTE in the sense that they are only present when the UE has data allocation; thus they are UE specific and confined to the time-frequency region where user data are allocated. Unlike LTE, NR does not utilize cell-specific reference signals, rather exclusively relies on user-specific demodulation reference signals (DM-RSs) for channel estimation, enabling efficient beamforming and other multi-antenna schemes. In NR, the reference signals are not transmitted unless there are data to transmit, thereby improving network energy efficiency and reducing inter-cell interference. Support for low-latency transmission is an important part of NR design. In a front-loaded DM-RS structure, the ref- erence signals and downlink control channel carrying scheduling information are located at the beginning of the slot; thus a device can start processing the received data immediately without prior buffering and time-domain interleaving across OFDM symbols, thereby mini- mizing the decoding delay. There are other types of reference signals such as phase tracking reference signals (PT-RS) which are used to counter phase noise at higher frequencies. 