Method and apparatus for transmitting communication signals using transmission space diversity and frequency diversity

• US 6,006,075 A
• Filed: 06/18/1996
• Issued: 12/21/1999
• Est. Priority Date: 06/18/1996
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Smith, David Anthony, Almgren, Knut Magnus, Olofsson, H.ang.kan Gunnar
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/665,501
• Time in Patent Office: 1,281 Days
• Field of Search: 455/101, 455/102, 455/103, 455/560, 455/561, 455/562, 375/299
• US Class Current: 455/101
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 7/0604 with predefined switching scheme
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 1/06 using space diversity

Abstract

A transmitter diversity assembly and an associated method for a radio transmitter. When coupled to a radio transmitter to form a portion thereof, signal diversity is created to overcome multi-path fading. A plurality of antennas are freely selectable to be coupled to receive bursts of a communication signal, modulated to be transmitted on any of selected carriers. By altering the carriers upon which the bursts of the communication signal are transmitted and the spatially-separated antennas used to transduce the bursts of the communication signal, both transmission space diversity and frequency diversity is created.

Claims

1. A transmitter diversity assembly for a communication station operable to generate a communication signal of at least one selected carrier frequency to be transmitted upon at least one communication channel, said transmitter diversity assembly comprising:

a set of spaced-apart antennas, each antenna of said set of antennas selectively connectable to receive the communication signal generated at the communication station and to transduce the communication signal when applied thereto;

switching circuitry actuatable into selected switch positions for selectively connecting selected antennas of said set of antennas to receive the communication signal generated by the communication station;

a selector coupled to said switching circuitry, said selector for selecting the switch positions into which said switching circuitry is actuated, the switch positions selected by the selector selected to connect a sequence of different ones of the selected antennas to receive the communication signal, the communication signal generated of any of the at least one selected carrier frequency connectable to any antenna of said set of spaced-apart antennas, thereby to transduce the communication signal at the different ones of the selected antennas;

wherein the communication station comprises a communication signal generator and a set of transmitting elements, wherein each antenna of said set of antennas is connected to a transmitting element of the set of transmitting elements, and wherein said switching circuitry comprises a baseband switch coupled between the communication signal generator and the transmitting elements; and

wherein the at least one communication channel upon which the communication signal is to be transmitted comprises a plurality of communication channels, wherein the transmitting elements of the set of transmitting elements each modulate the communication signal at different carrier frequencies corresponding to different communication channels of the set of communication channels, and wherein selection by said selector of the switch positions into which said switching circuitry is actuated is determinative of both the antenna at which the communication signal is transduced and the communication channel upon which the communication signal is transmitted.

2. The transmitter diversity assembly of claim 1 wherein the selected switch positions into which said selector actuates said switching circuitry are selected responsive to previous switch positions into which the switching circuitry previously had been actuated.

3. A transmitter diversity assembly for a communication station operable to generate a communication signal of at least one selected carrier frequency to be transmitted upon at least one communication channel, said transmitter diversity assembly comprising:

a set of spaced-apart antennas, each antenna of said set of antennas selectively connectable to receive the communication signal generated at the communication station and to transduce the communication signal when applied thereto;

switching circuitry actuatable into selected switch positions for selectively connecting selected antennas of said set of antennas to receive the communication signal generated by the communication station;

a selector coupled to said switching circuitry, said selector for selecting the switch positions into which said switching circuitry is actuated, the switch positions selected by the selector selected to connect a sequence of different ones of the selected antennas to receive the communication signal, the communication signal generated of any of the at least one selected carrier frequency connectable to any antenna of said set of spaced-apart antennas, thereby to transduce the communication signal at the different ones of the selected antennas; and

wherein the communication station comprises a communication signal generator and a set of transmitting elements, each transmitting element of the set of transmitting elements coupled to the communication signal generator, and wherein said switching circuitry comprises a radio frequency switch coupled between each transmitting element of the set of transmitting elements and said set of antennas.

4. The transmitter diversity assembly of claim 3 wherein the at least one communication channel upon which the communication signal is to be transmitted comprises a plurality of communication channels, wherein the set of transmitting elements comprises a single transmitting element, the single transmitting element for modulating the communication signal at a carrier frequency corresponding to any selected communication channel of the plurality of communication channels and wherein the antenna of said set of antennas coupled by said switching circuitry to receive the communication signal transduces the communication signal to be transmitted upon the communication channel corresponding to the carrier frequency at which the single transmitting element modulates the communication signal.

5. A transmitter diversity assembly for a communication station operable at least to transmit communication signals upon at least one communication channel, said transmitter diversity assembly comprising:

a set of antennas, each antenna of said set selectively coupled to the communication station to transduce the communication signals formed at the communication station;

switching circuitry actuatable into selected switch positions for selectively coupling selected antennas of said set of antennas to the communication station;

a selector coupled to said switching circuitry, said selector for actuating the switching circuitry into the selected switch positions, the selected switch positions into which the switching circuitry is actuated responsive to indications of at least one transmission characteristic of the at least one communication channel;

wherein the communication station comprises at least one transmitter for generating the communication signals and wherein said switching circuitry is coupled between the antennas of said set of antennas and the transmitter;

wherein the transmitter of the communication station transmits the communication signals pursuant to a frequency hopping scheme on a plurality of frequency channels and wherein the transmission characteristic of the at least one communication channel comprises an indication of a fading characteristic; and

wherein said selector further comprises a memory device for storing selections by said selector of the selected switch positions into which said switching circuitry is actuated and the frequency channel of the plurality of frequency channels upon which the communication signal is transmitted when said switching circuitry is actuated into the selected switch positions.

6. The transmitter diversity assembly of claim 5 wherein the selected switch positions into which said selector actuates said switching circuitry are selected responsive to:

the fading characteristic, the frequency channel of the plurality of frequency channels upon which the communication signals are to be transmitted, and stored selections, stored at the memory device, of the selected switch positions and the frequency channels associated therewith which are within a coherence bandwidth of the frequency channel upon which the communication signals are to be transmitted.

7. The transmitter diversity assembly of claim 6 wherein each selected switch position of the selected switch positions is selected to couple an antenna of said set of antennas which the stored selections stored by said memory device indicates to have least recently been coupled to the transmitter when transmitting the communication signal upon a frequency channel within the frequency bandwidth about the frequency channel upon which the communication signal is to be transmitted.

8. The transmitter diversity assembly of claim 5 wherein the at least one communication channel comprises a plurality of communication channels, wherein said transmitter is tunable to generate communication signals upon any communication channel of said plurality of communication channels, and wherein said switching circuitry is actuatable into a selected position of the selected switch positions to couple any antenna of said set of antennas with the transmitter.

9. The transmitter diversity assembly of claim 5 wherein which said selector actuates said switching circuitry sequentially into a plurality of switch positions, the switch positions into which said switching circuitry is actuated being dependent upon the transmission characteristics of the at least one communication channel and previous switch positions into which said switching circuitry has been actuated.

10. The transmitter diversity assembly of claim 5

wherein the fading characteristic is of at least one downlink communication channel.

11. A transmitter diversity assembly for a communication station operable at least to transmit communication signals upon at least one communication channel, said transmitter diversity assembly comprising:

a set of antennas, each antenna of said set selectively coupled to the communication station to transduce the communication signals formed at the communication station;

switching circuitry actuatable into selected switch positions for selectively coupling selected antennas of said set of antennas to the communication station;

a selector coupled to said switching circuitry, said selector for actuating the switching circuitry into the selected switch positions, the selected switch positions into which the switching circuitry is actuated responsive to indications of at least one transmission characteristic of the at least one communication channel;

wherein the communication station comprises at least one transmitter for generating the communication signals and wherein said switching circuitry is coupled between the antennas of said set of antennas and the transmitter;

wherein the at least one transmitter of the communication station comprises a plurality of transmitting elements and the at least one communication channel comprises a plurality of communication channels, each transmitting element associated with a different communication channel, and wherein said switching circuitry comprises a radio frequency switching matrix actuatable into a switch position to couple any antenna of said set of antennas with any transmitting element of said set of transmitting elements; and

wherein the communication station includes a baseband signal generator for generating baseband signals, the baseband signals mixed with up mixing signals applied to the transmitting elements of the transmitter and wherein said switching circuitry comprises a baseband switch for coupling the baseband signal generator to a selected transmitting element, thereby to apply the baseband signals to the selected transmitting element, and thereby to form communication signals for transmission upon selected ones of the communication-channels.

12. The transmitter diversity assembly of claim 11 wherein the transmission characteristics of the at least one communication channel comprises a coherence space formed of a transmission space exhibiting similar transmission characteristics.

13. The method of claim 11 wherein the transmission characteristic of the at least one communication channel comprises an indication of a fading characteristic of the at least one communication channel.

14. The method of claim 11 wherein the transmission characteristic of the at least one communication channel comprises indications of a coherence bandwidth formed of frequency bandwidth exhibiting similar transmission characteristics.

15. The method of claim 11 wherein the transmission characteristic of the at least one communication channel comprises indications of a coherence space formed of a transmission distance range including a transmission distance extending between at least one antenna of the set of antennas and a remote station.

16. A transmitter diversity assembly for a communication station operable at least to transmit communication signals upon at least one communication channel, said transmitter diversity assembly comprising:

a set of antennas, each antenna of said set selectively coupled to the communication station to transduce the communication signals formed at the communication station;

switching circuitry actuatable into selected switch positions for selectively coupling selected antennas of said set of antennas to the communication station;

a selector coupled to said switching circuitry, said selector for actuating the switching circuitry into the selected switch positions, the selected switch positions into which the switching circuitry is actuated responsive to indications of at least one transmission characteristic of the at least one communication channel;

wherein the communication station further comprises a receiver for receiving communication signals transmitted thereto upon at least one unlink communication channel and wherein the transmission characteristics of the at least one communication channel comprise path gain levels of the communication signals transmitted upon the at least one unlink channel to each antenna of said set of antennas; and

wherein said selector actuates said switching circuitry sequentially into a plurality of switch positions, the switch positions into which said switching circuitry is actuated being dependent upon the path gain levels and previous switch positions into which said switching circuitry has been actuated.

17. A transmitter diversity assembly for a communication station operable at least to transmit communication signals upon at least one communication channel, said transmitter diversity assembly comprising:

a set of antennas, each antenna of said set selectively coupled to the communication station to transduce the communication signals formed at the communication station;

switching circuitry actuatable into selected switch positions for selectively coupling selected antennas of said set of antennas to the communication station;

a selector coupled to said switching circuitry, said selector for actuating the switching circuitry into the selected switch positions, the selected switch positions into which the switching circuitry is actuated responsive to indications of at least one transmission characteristic of the at least one communication channel;

wherein the communication station further comprises a receiver for receiving communication signals transmitted thereto upon at least one uplink communication channel and wherein the transmission characteristics of the at least one communication channel comprise path gain levels of the communication signals transmitted upon the at least one uplink channel to each antenna of said set of antennas; and

wherein said selector is further operable responsive to variances of the path gain levels of the communication signals transmitted to each antenna of said set of antennas and wherein the switch positions into which said switching circuitry is actuated is further dependent upon the variances of the path gain levels.