This is a glossary of wireless terms.
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| 3 |
| 3GPP: Third Generation Partnership Project. The name of the organization which is responsible for Wideband CDMA standards in Europe. |
| 3GPP2: A reference to the North American Standards body responsible for CDMA standards. (IS-95, DO (Rev 0,A,B,C), UMB) |
| A |
| AoA:
Angle of Arrival (AoA) is the angle between the propagation direction of a radio wave incident at an antenna array and some reference direction. AoA is used to determine Direction of Arrival (DoA) for location. | |
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| Array Gain:
Historically, this term originated in relation to sonar array processing. Array gain relates to how the signals from the different antennas are collectively processed. Array gain can be realized irrespective of whether the fading is uncorrelated or correlated across the antenna elements. Typical examples of array gain are beamforming gain for transmit array gain, and the gain from processing the composite signal at the receive end such as with maximal ratio combining. To realize array gain, Channel State Information (CSI) is required at transmitter or receiver so as to respectively maximize the signal energy in the direction of the user or to extract the signal energy from the composite received signal including interference. At the transmitter, per antenna weights are adapted based on available channel state information to direct the right amount of signal energy to each element of the antenna array such that the SINR at the receive end is maximized. At the receiver, CSI is normally available and is leveraged to combine multiple copies of the received signal and/or iteratively extract the strongest signals such that the SINR is maximized. Array gain varies with the algorithm used, and is a function of number of transmit and receive antennas.
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| ASIC: Application Specific Integrated Circuit |
| B |
| BLAST: Bell Labs Layered Space Time: A well-known method of Spatial Multiplexing |
| BS: Base Station |
| C |
| CDMA: Code Division Multiple Access |
| CSI: Channel State Information (CSI) Channel State Information (CSI) is necessary to realize array gain with diversity antennas. Cases: CSI is easily available for TDD systems at both transmitter and receiver since they operate on the same carrier frequency. In FDD, CSI feedback is required from the receiver for transmitter to use How to measure CSI: Training based Blind CSI eats up bandwidth: Training Feedback CSI Accuracy and Tradeoff: The more accurate the CSI the more the benefit from its use. However, to obtain accurate CSI in highly variable channel conditions, frequent transmission of pilot symbols may be needed, which may be impractical from a bandwidth conservation perspective. There is a tradeoff between CSI accuracy and channel bandwidth required to transmit CSI pilots or feedback. CSI information gathered at the receiver is fed back to the transmitter, requiring an allocation of some bandwidth. Pilot symbols are alternated between antennas, or orthogonal pilots may be used, and use up some of the bandwidth. Receiver exploits properties of the received signal (e.g., constant envelope, cyclostationarity) to estimate channel Pilot symbols are inserted into the transmitted signal. Receiver gains channel knowledge through pilot symbol extraction to construct a channel estimate per data symbol transmitted.• No CSI: Neither transmitter or receiver know the channel • CSI at receiver: Receiver knows channel perfectly, transmitter does not have CSI • Perfect CSI: Transmitter and receiver know the channel perfectly (perfect CSI) • Partial CSI: Transmitter/receiver knows channel partially | |
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| D |
| DOA: DOA: Direction of Arrival
Direction of arrival is the direction from which the multipath signals arrives at the antenna. Direction of Arrival information is used in location estimation. Direction of arrival is determined using different methods: e.g., Angle of Arrival (AoA) and Time Difference of Arrival (TDoA) Received signal varies depending on angle/direction of arrival Angle of Arrival (AoA) or Direction of Arrival (DoA) vary based on (multiple) antenna location, obstruction, etc Independent signals arriving from/to spatially separated antennas have different angle/direction of arrival | |
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