# US 2014/0192690 A1 · Ue beaconing using rach transmissions for small cells

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- Number: US 2014/0192690 A1
- Document ID: US20140192690A1
- Status: Published application
- Kind: A1
- Application number: 13/734,952
- Filed: 2013-01-05
- Published: 2014-07-10
- Earliest claimed: 2013-01-05
- Assignees: QUALCOMM Incorporated
- Applicants: Qualcomm Incorporated
- Inventors: Kaushik CHAKRABORTY; Bongyong SONG; Soumya DAS
- Web page: https://patentgrep.com/patent/US20140192690A1

## CPC

- H04W 48/16: Discovering, processing access restriction or access information
- H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals}
- H04W 52/0206: {in access points, e.g. base stations}
- H04W 84/045: {using private Base Stations, e.g. femto Base Stations, home Node B}
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A method of beacon detection performed by a small cell device includes: exchanging beacon parameters with a user equipment (UE); entering a low power mode after exchanging the beacon parameters with the UE; receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode; entering a high power mode in response to receiving the beacon; and associating with the UE while in the high power mode. The method of beacon detection allows a small cell device to transition from a low power mode to a high power mode in an efficient manner. The transmission may be triggered by a user equipment that is entering a service area of the small cell device.

## Claims

### Claim 1

A method of beacon detection performed by a small cell device, the method comprising:
exchanging beacon parameters with a user equipment (UE);
entering a low power mode after exchanging the beacon parameters with the UE;
receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode;
entering a high power mode in response to receiving the beacon; and
associating with the UE while in the high power mode.

### Claim 2 (depends on 1)

The method of claim 1, wherein the beacon parameters are exchanged with the user equipment while in the high power mode.

### Claim 3 (depends on 1)

The method of claim 1,
wherein in the low power mode, a listening component of the small cell device for receiving the beacon is activated and a transceiver of the small cell device for receiving data packets is deactivated; and
wherein in the high power mode, the listening component of the small cell device is activated and the transceiver of the small cell device is activated.

### Claim 4 (depends on 1)

The method of claim 1, wherein the small cell device enters the low power mode when the UE is not in coverage of the small cell device.

### Claim 5 (depends on 1)

The method of claim 1, wherein the small cell device is a femtocell unit.

### Claim 6 (depends on 1)

The method of claim 1, wherein the associating comprises performing a subsequent RACH procedure to complete cell reselection.

### Claim 7

A method of beacon transmission performed by a user equipment, comprising:
exchanging beacon parameters with a small cell device;
detecting presence of the small cell device;
transmitting, in response to the detecting, a beacon in a random access channel (RACH) preamble containing the beacon parameters to the small cell device; and
associating with the small cell device.

### Claim 8 (depends on 7)

The method of claim 7,
wherein the presence of the small cell device is detected while the small cell device is in a low power mode;
wherein the parameters are exchanged with the user equipment while the small cell device is a high power mode; and
wherein the user equipment is associated with the small cell device while the small cell device is in the high power mode.

### Claim 9 (depends on 7)

The method of claim 7, wherein the associating comprises performing a subsequent RACH procedure to complete cell reselection.

### Claim 10 (depends on 7)

The method of claim 7, wherein the presence of the small cell device is detected via at least one of a neighborhood map, out-of-band signaling, and position estimation.

### Claim 11

A method of beacon detection performed by a small cell device, comprising:
exchanging beacon parameters with a user equipment (UE);
transmitting the beacon parameters to a neighboring cell device;
entering a low power mode after exchanging the beacon parameters with the UE;
receiving a notification from the neighboring cell device in response to the neighboring cell receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode;
entering a high power mode in response to receiving the notification; and
associating with the UE while in the high power mode.

### Claim 12 (depends on 11)

The method of claim 11, wherein the neighboring cell device comprises a small cell device.

### Claim 13 (depends on 11)

The method of claim 11, wherein the neighboring cell device comprises a macro cell device.

### Claim 14 (depends on 11)

The method of claim 11, wherein the notification is received via a backhaul to the small cell device.

### Claim 15 (depends on 11)

The method of claim 11, wherein the beacon parameters are exchanged with the UE while in the high power mode.

### Claim 16 (depends on 11)

The method of claim 11,
wherein in the low power mode, a listening component of the small cell device for receiving the notification is activated and a transceiver of the small cell device for receiving data packets is deactivated; and
wherein in the high power mode, the listening component of the small cell device is activated and the transceiver of the small cell device is activated.

### Claim 17 (depends on 11)

The method of claim 11, wherein the small cell device enters the low power mode when the UE is not in coverage of the small cell device.

### Claim 18 (depends on 11)

The method of claim 11, wherein the small cell device is a femtocell unit.

### Claim 19 (depends on 11)

The method of claim 11, wherein the associating comprises performing a subsequent RACH procedure to complete cell reselection.

### Claim 20

A method of beacon detection transmission by a user equipment, comprising:
exchanging beacon parameters with a small cell device;
detecting presence of the neighboring cell device associated with the small cell device;
transmitting, in response to the detecting, a beacon in a random access channel (RACH) preamble containing the beacon parameters to the neighboring cell device; and
associating with the small cell device.

### Claim 21 (depends on 20)

The method of claim 20,
wherein the presence of the neighboring cell device is detected while the small cell device is in a low power mode;
wherein the parameters are exchanged with the user equipment while the small cell device is a high power mode; and
wherein the user equipment is associated with the small cell device while the small cell device is in the high power mode.

### Claim 22 (depends on 20)

The method of claim 20, wherein the associating comprises performing a subsequent RACH procedure to complete cell reselection.

### Claim 23 (depends on 20)

The method of claim 20, wherein the presence of the small cell device is detected via at least one of a neighborhood map, out-of-band signaling, and position estimation.

### Claim 24

A method of beacon detection performed by a small cell device, comprising:
exchanging beacon parameters with a user equipment (UE);
transmitting the beacon parameters to a first neighboring cell device;
entering a low power mode after exchanging the beacon parameters with the UE;
receiving, while in the low power mode, at least one of (i) a beacon in a random access channel (RACH) message containing an identifier of the small cell, and (ii) a notification from the first neighboring cell device in response to the neighboring cell device detecting a beacon in a RACH message from the UE containing an identifier of the small cell device;
entering a high power mode in response to receiving the second notification; and
associating with the UE while in the high power mode.

### Claim 25 (depends on 24)

The method of claim 24, wherein the RACH message includes an identifier for the small cell device.

### Claim 26 (depends on 25)

The method of claim 25, wherein the identifier comprises a SRNC-ID.

### Claim 27 (depends on 24)

The method of claim 24, wherein the notification is received from the neighboring cell device to which the UE transmitted the RACH message.

### Claim 28 (depends on 24)

The method of claim 24, wherein the notification is received from a different neighboring cell device to which the UE transmitted the RACH message.

### Claim 29 (depends on 24)

The method of claim 24, wherein the at least one of the neighboring cell devices comprises a small cell device.

### Claim 30 (depends on 24)

The method of claim 24, wherein the at least one of the neighboring cell devices comprises a macro cell device.

### Claim 31 (depends on 24)

The method of claim 24, wherein the notification is received via a backhaul to the small cell device.

### Claim 32 (depends on 24)

The method of claim 24, wherein the beacon parameters are exchanged with the UE while in the high power mode.

### Claim 33

A method of beacon transmission performed by a user equipment, comprising:
exchanging beacon parameters with a small cell device;
detecting presence of a neighboring cell device;
transmitting, in response to detecting the neighboring cell device, a beacon in a random access channel (RACH) message containing the beacon parameters; and
associating with the small cell device.

### Claim 34 (depends on 33)

The method of claim 33, wherein the RACH message is transmitted to the detected neighboring cell device.

### Claim 35 (depends on 33)

The method of claim 33, wherein the RACH message includes an identifier for the small cell device.

### Claim 36 (depends on 33)

The method of claim 33, wherein the identifier comprises a serving radio network control identifier (SRNC-ID).

### Claim 37 (depends on 33)

The method of claim 33,
wherein the presence is detected while the small cell device is in a low power mode;
wherein the parameters are exchanged with the user equipment while the small cell device is a high power mode; and
wherein the user equipment is associated with the small cell device while the small cell device is in the high power mode.

### Claim 38 (depends on 33)

The method of claim 33, wherein the associating comprises performing a subsequent RACH procedure to complete cell reselection.

### Claim 39 (depends on 33)

The method of claim 33, wherein the presence of the small cell device is detected via at least one of a neighborhood map, out-of-band signaling, and position estimation.

### Claim 40

An apparatus for beacon detection, the apparatus comprising:
means for exchanging beacon parameters with a user equipment (UE);
means for entering a low power mode after exchanging the beacon parameters with the UE;
means for receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode;
means for entering a high power mode in response to receiving the beacon; and
means for associating with the UE while in the high power mode.

### Claim 41

An apparatus for beacon detection, the apparatus comprising:
a processor configured for:
exchanging beacon parameters with a user equipment (UE);
entering a low power mode after exchanging the beacon parameters with the UE;
receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode;
entering a high power mode in response to receiving the beacon; and
associating with the UE while in the high power mode.

### Claim 42

A computer program product for beacon detection, the computer program product comprising:
a computer-readable storage medium comprising code for:
exchanging beacon parameters with a user equipment (UE);
entering a low power mode after exchanging the beacon parameters with the UE;
receiving, from the UE, a beacon in a random access channel (RACH) preamble containing the beacon parameters while in the low power mode;
entering a high power mode in response to receiving the beacon; and
associating with the UE while in the high power mode.