Enhancing wimax performance with subcriber stations acting as ad hoc repeaters

• US 20080186900A1
• Filed: 11/30/2007
• Published: 08/07/2008
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Chang, Chu-Rui, Bassirat, Farhad
• Granted Patent: US 8,717,965 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/14 Relay systems
• CPC Class Codes: H04B 7/15542 Selecting at relay station its transmit and receive resources selection of wireless resources by user or terminal H04W72/02; arrangements affording multiple use of the transmission path by two-dimensional division of the resources H04L5/0003, or by allocating sub-channels H04L5/003
• CPC Class Codes: H04B 7/15557 Selecting relay station operation mode, e.g. between amplify and forward mode, decode and forward mode or FDD - and TDD mode
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 72/1263 Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A wireless communications network includes a subscriber station acting as a relay station (or ad-hoc repeater) between another subscriber station (a child subscriber station) and a base station (BTS) when there is no LOS between the other subscriber station and the base station, but there is LOS between the other subscriber station and the relay station. The BTS divides each of the downlink (DL) and uplink (UL) sub-frames into P1 and P2 portions and schedules transmissions of child subscriber DL and UL data during P1 of the DL and UL frames (from the BTS), respectively. The relay station receives the child subscriber DL and UL data, stores the data, and transmits/forwards the child subscriber DL and UL data during P2 of the DL and UL frame (to the BTS), respectively.

Claims

1. A method of operating a base station in a wireless communications network, the method comprising:

scheduling the base station to transmit downlink (DL) data for a subscriber station within a first portion P1 of a DL frame;

transmitting one or more DL frames including scheduling information, the scheduling information operable for scheduling transmission of the DL data from a relay station located remotely from the subscriber station within a second portion P2 of a DL frame, for scheduling transmission of uplink (UL) data from the subscriber station within a first portion P1 of a UL frame, and for scheduling transmission of the UL data from the relay station to the base station within a second portion P2 of a UL frame; and

receiving the UL data from the relay station.

2. A method of operating a relay station in a wireless communications network, the method comprising:

receiving a first radio frequency (RF) signal from a base station carrying downlink (DL) data for a subscriber station located remotely from the relay station, the first RF signal received during a first portion P1 of a DL frame;

demodulating the first RF signal to recover the DL data;

storing the DL data;

modulating the stored DL data to generate a second RF signal;

transmitting the second RF signal during a second portion P2 of a DL frame for reception by the subscriber station.

3. The method in accordance with claim 2 wherein the same DL frame carries the first RF signal and the second RF signal.

4. The method in accordance with claim 2 further comprising:

receiving a third radio frequency (RF) signal from the subscriber station carrying downlink (UL) data, the third RF signal received during a first portion P1 of a UL frame;

demodulating the third RF signal to recover the UL data;

storing the UL data;

modulating the stored UL data to generate a fourth RF signal;

transmitting the fourth RF signal during a second portion P2 of a UL frame for reception by the base station.

5. The method in accordance with claim 4 wherein the same UL frame carries the third RF signal and the fourth RF signal.

6. The method in accordance with claim 2 further comprising:

receiving a UL frame from the subscriber station;

measuring signal-to-noise ratio (SNR) of the received UL frame;

comparing the measured SNR to a predetermined SNR threshold, and if the measured SNR meets the predetermined threshold, transmitting the measured SNR to the base station.

7. A base station for communicating with one or more remote communication devices in a wireless network, the base station comprising:

a processor;

memory coupled to the processor;

a transceiver, having an antenna coupled thereto, operable for transmitting and receiving DL frames and UL frames to the one or more remote communications devices; and

a scheduler operable for;

scheduling the base station to transmit downlink (DL) data for a first communication device within a first portion P1 of a DL frame,

scheduling transmission of the DL data from a second communication device located remotely from the first communication device within a second portion P2 of a DL frame,

scheduling transmission of uplink (UL) data from the first communication device within a first portion P1 of a UL frame, and

scheduling transmission of the UL data from the second communication device to the base station within a second portion P2 of a UL frame.