Basestation RSSI and BER feedback signal quality display and transmit diversity

• US 6,035,183 A
• Filed: 12/09/1997
• Issued: 03/07/2000
• Est. Priority Date: 12/09/1997
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Corporation
• Inventors: Todd, Stephen Ross, Osborne, Greg
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): RAMOS FELICIANO, ELISEO
• Application Number:
  US08/987,209
• Time in Patent Office: 819 Days
• Field of Search: 455/226.2, 455/226.4, 455/67.7, 455/67.3, 455/70, 455/277.1, 455/277.2, 455/101, 455/115
• US Class Current: 455/226.2
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04B 7/0814 based on current reception conditions, e.g. switching to different antenna when signal level is below threshold

Abstract

A system and method for a fixed wireless access terminal to determine and display to a user forward link and reverse link RSSI and BER signal quality information. The reverse link information is measured by a basestation and transmitted to the terminal in a message. The quality information is displayed to the user with sufficient resolution to allow the user to adjust the location of the fixed wireless access terminal to optimize the quality of the link. The reverse link information may also be used as a basis for performing transmit switch diversity.

Claims

1. A method for a fixed wireless access terminal to indicate the quality of a mobile communications link between the fixed wireless access terminal and a basestation, the mobile communications link including a forward link from the basestation to the terminal, and a reverse link from the terminal to the basestation, the method comprising the steps of:

a) the terminal measuring an RSSI in the forward link and a BER in the forward link;

b) the basestation determining an RSSI in the reverse link and a BER in the reverse link and conveying this to the terminal in a message;

c) the terminal determining a link quality metric on the basis of both the forward link BER and RSSI and the reverse link BER and RSSI; and

d) the terminal displaying the link quality metric.

2. A method according to claim 1 wherein step d) comprises displaying the link quality metric in bar graph form with a resolution of 2 dB per pixel or greater.

3. A method according to claim 1 further comprising the step of c1) determining whether the reverse link is limiting or the forward link is limiting and wherein in step d), the RSSI for the limiting link is displayed in bar graph form.

4. A method according to claim 3 wherein step c1) is performed by comparing the forward link RSSI with the reverse link RSSI to determine which link has the worse RSSI, and selecting that as the limiting link.

5. A method according to claim 4 further comprising the step of the terminal displaying a limiting link identifier which identifies which of the forward link and the reverse link is the limiting link.

6. A method according to claim 5 wherein the link quality information is a reverse link RSSI measurement and a reverse link BER measurement and further comprising the steps of:

the basestation comparing the reverse RSSI measurement and BER measurement to respective predetermined levels;

if either the reverse RSSI measurement is below its predetermined level, or if the BER measurement is above its predetermined level, the basestation sending a toggle message to the terminal;

the terminal performing said switch from one antenna to the other antenna on the basis of the toggle message.

7. A method according to claim 3 wherein in step c1) is performed by comparing the forward link BER with the reverse link BER to determine which link has the worse BER, and selecting that as the limiting link.

8. A method according to claim 1 further comprising the step of displaying a course link quality indicator, the course link quality indicator having at least two discrete values each representing a defined range of RSSI and BER values.

9. A method according to claim 8 wherein the course link quality indicator has either two, three, four or five discrete values.

10. A method according to claim 9 further comprising the step of periodically receiving in a message from the basestation containing a redefinition of the range of RSSI and BER values for each of said discrete values.

11. A method according to claim 1 wherein the link quality metric is only displayed when it is below a predetermined threshold.

12. A method according to claim 10 wherein the display of the link quality metric turns off after a delay period if the link quality metric exceeds the predetermined threshold.

13. A method according to claim 1 further comprising the steps of:

a) the basestation determining a link quality for the reverse link;

b) the basestation sending a message to the terminal on the basis of the link quality information;

c) the terminal receiving the message from the basestation, and on the basis of its contents either performing a switch from one transmit antenna to another transmit antenna, or not.

14. A method according to claim 13 wherein the link quality information is a reverse link RSSI measurement and a reverse link BER measurement and wherein said message contains these measurements, the method further comprising the steps of:

the terminal comparing the reverse RSSI measurement and BER measurement to respective predetermined levels;

if either the reverse RSSI measurement is below its predetermined level, or if the BER measurement is above its predetermined level, performing said switch from one antenna to the other antenna, and otherwise not performing the switch.

15. A fixed wireless access terminal for wireless connection to a basestation over a mobile communications link including a forward link from the basestation to the terminal, and a reverse link from the terminal to the basestation, the terminal comprising:

a display;

circuitry for receiving a message from said basestation containing a reverse link RSST and a reverse link BER;

circuitry for measuring a forward link DER and RSSI, determining a link quality metric on the basis of the forward link DER and RSSI and the reverse link DER and RSSI, and displaying the link quality metric on the display.

16. A terminal according to claim 15 wherein said display comprises a high resolution bar graph field for displaying an RSSI measurement.

17. A terminal according to claim 16 wherein the bar graph has a resolution of 2 dB or better.

18. A terminal according to claim 16 wherein said circuitry determines whether the reverse link is limiting or the forward link is limiting and wherein the RSSI for the limiting link is displayed in the graph.

19. A terminal according to claim 16 wherein the limiting link is identified by comparing the forward link RSSI with the reverse link RSSI to determine which link has the worse RSSI, and selecting that as the limiting link.

20. A terminal according to claim 16 wherein the limiting link is identified by comparing the forward link BER with the reverse link BER to determine which link has the worse BER, and selecting that as the limiting link.

21. A terminal according to claim 16 wherein said display further comprises a course link quality indicator field, wherein said circuitry updates the course link quality indicator to display one of at least two discrete values each representing a defined range of RSSI and BER values.

22. A terminal according to claim 16 wherein the display further comprises a limiting link identifier field, and the circuitry updates the limiting link identifier field to identify which link is the limiting link.

23. A fixed wireless access terminal for wireless connection to a basestation over a mobile communications link including a forward link from the basestation to the terminal, and a reverse link from the terminal to the basestation, the terminal comprising:

a first transmit antenna and a second transmit antenna;

a switch for alternatively connecting the first antenna and said second antenna to said wireless connection;

circuitry for receiving a message from the basestation respecting the quality of the reverse link, and for, on the basis of contents of the message, instructing said switch to switch from one transmit antenna to another transmit antenna, or not;

wherein the message contains link quality information consisting of a reverse link RSSI measurement and a reverse link BER measurement, wherein said circuitry compares the reverse RSSI measurement and BER measurement to respective predetermined levels, and if either the reverse RSSI measurement is below its predetermined level, or if the BER measurement is above its predetermined level, instructs said switch to switch from one antenna to the other antenna.