Methods of handling coverage within a wireless communications system

• US 8,848,654 B2
• Filed: 05/16/2007
• Issued: 09/30/2014
• Est. Priority Date: 12/29/2006
• Status: Expired due to Fees

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: He, Yu Jun, Shio, Steven, Xie, Hai Rong, Zheng, Ming Bin
• Primary Examiner(s): TAYLOR, NATHAN SCOTT
• Application Number:
  US11/798,702
• Publication Number:
  US 20080159226A1
• Time in Patent Office: 2,694 Days
• Field of Search: 370331-335, 455436-444
• US Class Current: 370/331
• CPC Class Codes: H04W 16/32 Hierarchical cell structures

Abstract

A first pilot signal is transmitted at a first frequency for a first coverage area (e.g., an outdoor area). A second pilot signal is transmitted at a second frequency for a second coverage area (e.g., an indoor area). The first pilot signal at the second frequency is transmitted into a portion of the second coverage area, the second coverage area at least overlapping with the first coverage area. Further, the first pilot signal is transmitted at the second frequency in the second coverage area. In an example, the first pilot signal at the first frequency is transmitted from an outdoor base station, the second pilot signal at the second frequency is transmitted by an indoor base station, the first pilot signal at the second frequency is transmitted into the second coverage area (e.g., an interior of a building from a building exit point) by an antenna (e.g., not necessarily at a base station) and the second pilot signal at the first frequency is transmitted by the indoor base station. The pilot signal configuration discussed above may facilitate call handoffs between the first and second coverage areas. For example, if the first coverage area is an outdoor area and the second coverage area is a building interior, the example pilot signal configuration may reduce pilot pollution.

Claims

1. A method of pilot signal transmission within a wireless communications system, comprising:

first transmitting, by a first base station, a first signal having a first frequency and a first pilot offset for a first coverage area;

second transmitting, by a second base station, a second signal having a second frequency and a second pilot offset for a second coverage area, the second frequency being different from the first frequency, the second pilot offset being different from the first pilot offset;

third transmitting, by a pilot antenna, a first indicating pilot signal having the second frequency and the first pilot offset for supporting handoff from the second base station to the first base station, a portion of the second coverage area overlapping with a portion of the first coverage area; and

fourth transmitting, by the second base station, a second indicating pilot signal having the first frequency and the second pilot offset for supporting handoff from the first base station to the second base station.

2. The method of claim 1, wherein inter-frequency hand-off is not enabled between the first signal and the second signal.

3. The method of claim 1, wherein the first base station is an outdoor base station and the second base station is an indoor base station.

4. The method of claim 1, wherein the pilot antenna is positioned within a building access point.

5. The method of claim 4, wherein the building access point is one of an entrance and an exit of a building.

6. The method of claim 1, wherein the wireless communications system operates in accordance with one of code division multiple access (CDMA) protocols, universal mobile telecommunication system (UMTS) protocols and evolution data optimized (EVDO) protocols.

7. The method of claim 1, wherein the first indicating pilot signal is transmitted into

a portion of the second coverage area such that a signal strength of the first indicating pilot signal increases as the portion is traversed from the second coverage area to the first coverage area.

8. The method of claim 1, further comprising:

receiving, by the second base station, a request from a mobile station to handoff to the second base station from the first base station if a measured signal strength of the second indicating pilot signal is greater than a measured signal strength of the first signal.

9. The method of claim 1, further comprising:

receiving, by the first base station, a request from a mobile station to handoff to the first base station from the second base station if a measured signal strength of the first indicating pilot signal is greater than a measured signal strength of the second signal.