Method for frequency division duplex communications
View Patent ↗The high quality PCS communications are enabled in environments where adjacent PCS service bands operate with out-of-band harmonics that would otherwise interfere with the system's operation. The highly bandwidth-efficient communications method combines a form of time division duplex (TDD), frequency division duplex (FDD), time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations. The method provides excellent fade resistance. The method enables changing a user's available bandwidth on demand by assigning additional TDMA slots during the user's session.
1. A system for highly bandwidth-efficient communications, comprising:
a base station receiver for receiving multiple incoming wireless signals from multiple remote stations, wherein the incoming wireless signals comprise multiple discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band during multiple time division multiple access (TDMA) intervals, and wherein the multiple remote stations transmitting to the base station receiver are not always identical in successive TDMA intervals; and
a base station transmitter for transmitting multiple outgoing wireless signals to multiple remote stations, wherein the outgoing wireless signals comprise multiple discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band during multiple time division multiple access (TDMA) intervals, and wherein the multiple remote stations intended to receive the outgoing wireless signals from the base station receiver is not always identical in successive TDMA intervals.
2. An apparatus for wireless communications, comprising:
a remote station, wherein multiple remote stations transmit multiple outgoing wireless signals to a base station receiver, wherein the outgoing wireless signals comprise multiple discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band during multiple time division multiple access (TDMA) intervals, and wherein the multiple remote stations transmitting to the base station receiver is not always identical in successive TDMA intervals; and
the remote station, wherein the multiple remote stations receive multiple incoming wireless signals from a base station transmitter, said incoming wireless signals comprising multiple discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band during multiple time division multiple access (TDM) intervals, wherein the multiple remote stations intended to receive the outgoing wireless signals from said base station receiver are not always identical in successive TDMA intervals.
3. The apparatus of claim 2 , wherein the remote station is a mobile wireless handset.
4. In a communications system based at least in part on orthogonal frequency division multiplexing (OFDM), a method for communicating between a base station and a remote station, the method comprising:
establishing a traffic channel from the base station to the remote station; and
based on a waveform transmitted from the base station to the remote station, synchronizing operations at the base station and the remote station, wherein the waveform comprises multiple discrete frequency tones that are orthogonal frequency division multiplexed, and wherein the synchronization includes aligning a processing window with the transmitted waveform and adjusting a reference oscillator at the remote station to operate at the same frequency as an oscillator at the base station.
5. In a communications system, a method for communicating between a base station and a remote station, the method comprising:
receiving information associated with the remote station wherein the information includes a direction of arrival (DOA) for the remote station and channel measurements for multiple channels;
computing a channel candidacy assessment factor (CAF) for each of the multiple channels based on the received information; and
where the channel candidacy assessment factor (CAF) for at least one of the multiple channels is acceptable, selecting the channel with the most favorable CAF.
6. The method of claim 5 , wherein each channel measurement comprises a received signal strength indicator (RSSI) and a signal to interference ratio (SINR).