B3P2 - Mobile and nomadic communications Flashcards
ad hoc mode (WiFi)
where all devices can directly message one other in a WiFi-net;
bipolar
where 1s and 0s and repped by +1 and -1 amplitudes;
channel bonding
merging 2+ channels for to get widerBandwidth;
channel equalisation (refSig)
where referenceSignals are used to check distortion;
channelisation (chip) code
where orthogonal chipCodes are used to distinguish simultaneously transmitted dataStreams;
chip
bipolarValues of fixedDuration concatenated to rep a 1 or 0;
correlation
where a signal is extracted from other signals;
cyclic prefix
where the last part of a symbol is copied and pasted to the start of the symbol, thereby protecting against inter-symbol interference;
delay spread
the waiting time for all zig-zags of a multipathSignal to arrive;
dynamic frequency selection (DFS) [radar]
where the device switches to a different channel if radar is detected in a 5MHz unlicensedBand;
fast link adaptation
adapting codeRates and modMethods to mobileComm conditions;
frequency division multiplexing (FDD)
where separate frequencyBands are used for uplink and downlink;
guard band
where an interval of spectrum is left unused to prevent interference between neighbouring bands;
high-speed packet access (HSPA)
uses 15 different 16-chipCodes allocated dynamically to users in WCDMA and 3G;
infrastructure mode
where all devices message via the accessPoint in a WiFi-network;