In a TDS-OFDM communications system, within a frame time, a transmitted signal comprising a preamble, a downlink sub-frame, and an uplink sub-frame. Within the downlink sub-frame, interposed between sub-frames are guard intervals that have known sequences positioned therein. The known sequences are
In a TDS-OFDM communications system, within a frame time, a transmitted signal comprising a preamble, a downlink sub-frame, and an uplink sub-frame. Within the downlink sub-frame, interposed between sub-frames are guard intervals that have known sequences positioned therein. The known sequences are used for an estimation of a received power. A method comprising the step of using a guard sequence in a guard interval of OFDM symbols of the received TDS-OFDM signals in the downlink or the uplink to estimate a received signal power and using the estimated signal power to calculate a CINR is provided.
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What is claimed is: 1. A TDS-OFDM communications system comprising: a frame such that within a frame time, a transmitted signal comprising a preamble, a downlink sub-frame, and an uplink sub-frame; and within the downlink sub-frame, interposed between OFDM symbols are guard intervals comprising kno
What is claimed is: 1. A TDS-OFDM communications system comprising: a frame such that within a frame time, a transmitted signal comprising a preamble, a downlink sub-frame, and an uplink sub-frame; and within the downlink sub-frame, interposed between OFDM symbols are guard intervals comprising known sequences being used for an estimation of a received power. 2. The system of claim 1, wherein both uplink and downlink use TDS-OFDM signals. 3. The system of claim 1, wherein both the downlink and uplink sub-frame consists of multiple OFDM symbols. 4. The system of claim 1, wherein the preamble may comprise one or more symbols. 5. The system of claim 1, wherein the preamble may be positioned at front, middle or last part of the frame, or distributed within the frame at different parts. 6. The system of claim 5, wherein the preamble symbol is constructed by a time-domain PN sequence, a frequency-domain PN sequence, or a partial-band frequency-domain PN sequence. 7. The system of claim 1, wherein a downlink OFDM symbol comprises a guard interval and a data part, within the guard interval at least one guard sequence is used, the guard sequence being at least one time-domain PN sequence. 8. The system of claim 1, wherein for a frequency reuse factor is one (frequency reuse factor=1), the guard sequence and OFDM data may occupy all or a part of an available bandwidth. 9. The system of claim 1, wherein for frequency reuse factor larger than 1 (frequency reuse factor>1), the available bandwidth is divided into at least two sub-bands, where sub-carriers in each sub-band are contiguous having all the sub-carriers joined and grouped together, or each sub-band are distributed having some sub-carriers free from joined and grouped together and be located at any position inside the whole available band. 10. The system of claim 1, wherein in the uplink, a bandwidth is divided into multiple sub-bands. 11. The system of claim 1, wherein the guard sequence and OFDM data occupy whole or partial assigned sub-bandwidth. 12. The system of claim 10, wherein the sub-carriers in each sub-band may be contiguous where all the sub-carriers are adjoined and grouped together. 13. The system of claim 10, wherein the sub-carrier is free from adjoining and positioned at any position inside an available band. 14. The system of claim 1, wherein the transmitted signal in each sub-band comprises multiple OFDM symbols, and wherein each OFDM symbol consists of a guard sequence and OFDM data with both the guard sequence and data are band-limited to the assigned sub-band. 15. The system of claim 1, wherein the guard sequence in the guard intervals of the OFDM symbols of the received TDS-OFDM signals, both in the downlink and uplink, can be used to estimate the received powers including signal power and interference power. 16. The system of claim 15, wherein the estimated powers can be used to calculate CINR. 17. The system of claim 16, wherein the CINR can be improved through using multiple CINR estimates using averaging or low-pass filtering. 18. The system of claim 1, wherein the transmitted signal in each sub-band is composed of multiple OFDM symbols, where each OFDM symbol includes a guard sequence and a data section. 19. The system of claim 18, wherein both the guard sequence and data are band-limited to an assigned sub-band and used for the power estimation. 20. A method comprising the step of using a guard sequence in a guard interval of OFDM symbols of the received TDS-OFDM signals in the downlink or the uplink to estimate a received signal power and using the estimated signal power to calculate a CINR.
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