LTE has been designed as a completely packet-oriented multi service system, without the reliance on circuit-switched connection-oriented protocols prevalent in its predecessors. In LTE, this philosophy is applied across all the layers of the protocol stack. The route towards fast packet scheduling over the radio interface was already opened by HSDPA, which allowed the transmission … Read more
LTE devices use several modulation techniques to modulate data and control information. These modulation techniques include: QPSK (2 bits per symbol), 16QAM (4 bits per symbol), and 64QAM (6 bits per symbol). All of these modulation techniques are supported in the downlink direction; and all but 64QAM, which is optional, are supported in the uplink … Read more
The Global Positioning System (GPS) is a radio-navigation system that employs RF transmitters in 24 satellites. The satellite configuration when completed will guarantee that a GPS receiver located anywhere on earth can receive RF signals from at least four satellites 24 hours a day (with unobstructed visibility). For commercial use, each satellite transmits unique bi-phase … Read more
Similar to any radio network, standard isolation would be required if equipment from different vendors are to be combined. Which including guard band, filtering as well as vertical/horizontal separation. In addition, indoor DAS (distributed antenna system) may contribute to interference problem particularly on the uplink due to PIM related inter-modulation, over drive of input RF … Read more