Part two provides an example of how decision-analysis software can be used to assess these four technologies against your own requirements. Evaluating the technologies This section of the article summarizes each technology's strengths and weaknesses. Its main drawback is low bandwidth efficiency. In systems using channel monitoring and dynamic frequency switching, QPSK also resists ingress and interfering frequencies. The use of short TDMA packets helps keep the signal-path delay low, but reduces the ratio of useful data to total transmitted data.
Longer packets improve the efficiency for data transmission.
For variable data rates, a system must be able to allocate additional time slots or vary packet lengths. Because of its robustness and maturity, QPSK has worked well in field trials and carries little risk. Headend burst demodulators are more difficult to find, especially when fast carrier and timing acquisition is required for short TDMA packets. Prospects for the long-term availability of QPSK equipment are encouraging, because QPSK is a mandatory constellation according to MCNS and IEEE 802.14 specifications. QPSK modems typically consume less power and require less processing than other technologies' modems.