Sub-access point, system, and method for adjusting power of transmission signal

• US 7,675,892 B2
• Filed: 10/19/2005
• Issued: 03/09/2010
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Min, In-hong
• Primary Examiner(s): Afshar; Kamran
• Assistant Examiner(s): FARAGALLA, MICHAEL A
• Application Number:
  US11/252,738
• Publication Number:
  US 20060083206A1
• Time in Patent Office: 1,602 Days
• Field of Search: 455/434, 455/41.2, 455/522, 455/436, 455/11.1, 370/338, 370/236, 370/331
• US Class Current: 370/338
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A sub-access point (AP), system, and method for adjusting a power level of a transmission signal, and more particularly, in which the power level of a transmission signal output from the sub-AP is adjusted based on received signal strength indicator (RSSI) readings and frame error rate (FER) of a main AP, thereby eliminating shadow areas and minimizing interference between the main AP and the sub-AP. The sub-AP includes a reception unit which receives a beacon frame and a data frame from a main AP, a RSSI checking unit which checks an RSSI of the main AP, a FER checking unit which checks an FER, and a control unit which determines a power level at which a transmission signal is to be transmitted based on the identified RSSI and the identified FER and causes a transmission signal to be output at the determined power level.

Claims

1. A sub-access point (AP) which adjusts the power of a transmission signal, the sub-AP comprising:

a reception unit which receives a beacon frame and a data frame from a main AP;

a received signal strength indicator (RSSI) checking unit which identifies an RSSI of the main AP with reference to the received beacon frame or the received data frame;

a frame error rate (FER) checking unit which identifies an FER from the received data frame;

a calculation unit which calculates a median RSSI and a median FER of the main AP; and

a control unit which determines a transmission level at which a transmission signal is to be transmitted based on the median RSSI and the median FER, and which causes a transmission signal to be output with a power level equivalent to the determined transmission level,

wherein the control unit examines a service set identifier (SSID) of the main AP with reference to the received beacon frame or the received data frame, and

the RSSI checking unit, the FER checking unit, the calculation unit, and the control unit operate only if the control unit determines, based on the examination, that the SSID of the main AP is the same as a SSID of the sub-AP.

2. The sub-AP of claim 1, further comprising:

a storage unit which stores a plurality of RSSI ranges, a plurality of FER ranges, a plurality of transmission levels corresponding to the respective RSSI ranges and the respective FER ranges, and a plurality of power levels corresponding to the respective transmission levels; and

a transmission unit which outputs a transmission signal with a power level corresponding to at least one of the median RSSI and the median FER calculated by the calculation unit.

3. The sub-AP of claim 2, wherein the calculation unit calculates the median RSSI using the equation:

$\mathrm{RSSI}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{RSSI}<br><br>\left(t\right)<br><br>\text{)}$

wherein i andj represent a location, and t represents time.

4. The sub-AP of claim 2, wherein the calculation unit calculates the median FER using the equation:

$\mathrm{FER}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{FER}<br><br>\left(t\right)<br><br>\text{)}$

wherein i and j represent a location, and t represents time.

5. A system for adjusting the power level of a transmission signal comprising:

a main AP which outputs at least one of a beacon frame and a data frame to wirelessly communicate with a plurality of wireless network devices in a wireless network; and

a sub-AP which receives at least one of the beacon frame and the data frame output from the main AP, calculates a median received signal strength indicator (RSSI) and a median frame error rate (FER) of the main AP based on the at least one of the received beacon frame and the received data frame, and outputs a transmission signal with a power level corresponding to the calculated median RSSI and the calculated median FER,

wherein the sub-AP examines a service set identifier (SSID) of the main AP with reference to the received beacon frame or the received data frame, and

the sub-AP calculates the median RSSI and the median FER and outputs the transmission signal with the power level corresponding to the calculated median RSSI and the calculated median FER only if, based on the examination, the SSID of the main AP is same as a SSID of the sub-AP.

6. The system of claim 5, wherein the sub-AP comprises:

a reception unit which receives a beacon frame and a data frame from a main AP;

a RSSJ checking unit which identifies an RSSI of the main AP with reference to the received beacon frame or the received data frame;

a FER checking unit which identifies the FER from the received data frame; and

a control unit which determines a power level at which a transmission signal is to be transmitted based on the identified RSSI and the identified FER and which causes a transmission signal to be output at the determined power level.

7. The system of claim 6, wherein the median RSSI is calculated using the equation:

$\mathrm{RSSI}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{RSSI}<br><br>\left(t\right)<br><br>\text{)}$

wherein i and j represent a location, and t represents time.

8. The system of claim 6, wherein the median FER is calculated using the equation:

$\mathrm{FER}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{FER}<br><br>\left(t\right)<br><br>\text{)}$

wherein i and j represent a location, and t represents time.

9. A method of adjusting a power level of a transmission signal of a sub-access point (AP) comprising:

receiving a data frame transmitted by a main AP;

examining a service set identifier (SSID) of the main AP with reference to the received data frame; and

based on the examination, if the SSJD of the main AP is same as a SSID of the sub-AP;

determining a received signal strength indicator (RSSI) and a frame error rate (FER) of the main AP with reference to the received data frame,

calculating a median RSSI and a median FER based on the determined RSSI and FER,

determining a transmission level based on the calculated median RSSI and the calculated median FER, and

outputting a transmission signal with a power level equivalent to the determined transmission level.

10. The method of claim 9, wherein the determining a transmission level comprises:

determining whether a transmission level corresponding to the calculated median RSSI is identical to a transmission level corresponding to the calculated median FER; and

if the transmission level corresponding to the calculated median RS SI is determined not to be identical to the transmission level corresponding to the calculated median FER, choosing the transmission level corresponding to the calculated median RSSI.

11. The method of claim 9, wherein the median RSSI is calculated using the equation:

$\mathrm{RSSI}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{RSSI}<br><br>\left(t\right)<br><br>\text{)}$

wherein i and j represent a location, and t represents time.

12. The method of claim 9, wherein the median FER is calculated using the equation:

$\mathrm{FER}<br><br>\left(i,j\right)=\mathrm{Median}<br><br><br><br>(\underset{t=1}{\overset{n}{\sum <br><br>}}<br><br>)<br><br>\mathrm{FER}<br><br>\left(t\right)<br><br>\text{)}$

wherein i and j represent a location, and t represents time.