# US 8,542,619 B2 · Method and apparatus for performing mobility measurements in a communication network

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- Number: US 8,542,619 B2
- Document ID: US8542619B2
- Status: Granted
- Kind: B2
- Application number: 13/073,532
- Filed: 2011-03-28
- Published: 2011-10-27
- Granted: 2013-09-24
- Earliest claimed: 2008-01-04
- Assignees: Motorola Mobility LLC
- Applicants: Kenneth A. Stewart; Jean-Aicard Fabien; Michael E. Buckley; Raja S. Bachu
- Inventors: Kenneth A. Stewart; Jean-Aicard Fabien; Michael E. Buckley; Raja S. Bachu
- Web page: https://patentgrep.com/patent/US8542619B2

## CPC

- H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)}
- H04L 27/2613: {Structure of the reference signals}
- H04W 36/302: {due to low signal strength}
- H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT}
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04W 48/18: Selecting a network or a communication service
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A method and apparatus for performing mobility measurement in a communication network (100) is described. The method comprises of receiving a subframe sequence pattern from a node in the communication network (100). The subframe sequence pattern indicates types of subframes being transmitted by a neighboring cell node (104) in a neighboring cell (112). The method includes receiving a subframe from a sequence of subframes transmitted by the neighboring cell node (104) in the neighboring cell (112), and determining that the received subframe is a multicast subframe based on the subframe sequence pattern. The method then includes performing a single cell-specific reference symbol measurement in response to determining that the received subframe is the multicast subframe.

## Claims

### Claim 1

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving a subframe sequence pattern from a node in the communication network, the subframe sequence pattern indicates a type of subframe being transmitted by a neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node; and
measuring power or signal-to-noise ratio of a reference symbol in the received subframe.

### Claim 2 (depends on 1)

The method of claim 1 further comprising:
determining that the received subframe is the unicast subframe based on the subframe sequence pattern; and
performing at least one measurement based on at least two OFDM symbol bearing cell-specific reference symbols in response to determining that the received subframe is the unicast subframe.

### Claim 3 (depends on 1)

The method of claim 1, wherein receiving the subframe sequence pattern comprises receiving the subframe sequence pattern from a serving cell node in a serving cell, wherein the serving cell is a cell in which the mobile device is currently located.

### Claim 4 (depends on 1)

The method of claim 1, wherein receiving the subframe sequence pattern comprises receiving the subframe sequence pattern from the neighboring cell node.

### Claim 5 (depends on 1)

The method of claim 1, wherein the subframe sequence pattern is received over a broadcast control channel (BCH) or a multicast control channel (MCCH).

### Claim 6 (depends on 1)

The method of claim 1, wherein the subframe sequence pattern indicates a sequence pattern of unicast and multicast subframes transmitted by the neighboring cell node.

### Claim 7

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving a subframe sequence pattern from a node in the communication network, the subframe sequence pattern indicates a type of subframe being transmitted by a neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node;
extracting a sequence number from the received subframe, wherein the sequence number indicates a position in the sequence of subframes transmitted by the neighboring cell node;
identifying a type of subframe present, in the subframe sequence pattern, at a position associated with the extracted sequence number;
considering the received subframe as the multicast subframe when the identified type is a multicast type; and
considering the received subframe as the unicast subframe when the identified type is a unicast type.

### Claim 8

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving a subframe sequence pattern from a node in the communication network, the subframe sequence pattern indicates a type of subframe being transmitted by a neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols; and
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node,
wherein the received subframe sequence pattern is independent of a subframe sequence pattern of the serving cell node.

### Claim 9

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving an indicator from a serving cell node, wherein the indicator indicates a type of subframe being transmitted by at least one neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols; and
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node,
wherein the indicator indicates that a subframe sequence pattern of each neighboring cell node is same as a subframe sequence pattern.

### Claim 10 (depends on 9)

The method of claim 9, wherein the indicator is received over a control channel.

### Claim 11

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving an indicator from a serving cell node, wherein the indicator indicates a type of subframe being transmitted by at least one neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node;
determining that the received subframe is the unicast subframe based on the received indicator, wherein determining that the received subframe is the unicast subframe comprises:
extracting a binary value from the received indicator;
considering no neighboring cell node transmits at least one multicast subframe when the extracted binary value is a second binary value; and
ascertaining that the received subframe is the unicast subframe in response to considering no neighboring cell transmits at least one multicast subframe; and
performing at least one measurement based on at least two symbol bearing cell-specific reference symbols in response to determining that the received subframe is the unicast subframe.

### Claim 12

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving an indicator from a serving cell node, wherein the indicator indicates a type of subframe being transmitted by at least one neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node,
wherein the received indicator is associated with each of at least two carrier frequencies in the communication network.

### Claim 13

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving an indicator from a serving cell node, wherein the indicator indicates a type of subframe being transmitted by at least one neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node,
wherein performing the single reference symbol measurement comprises measuring power of a first reference symbol in the received subframe when the received subframe is the multicast subframe, the measured power indicating a power level in the neighboring cell.

### Claim 14

An apparatus in a mobile device for mobility measurements in a communication network, the apparatus comprising:
a transceiver configured to receive a subframe sequence pattern from a node in the communication network, wherein the subframe sequence pattern indicates a type of subframe being transmitted by a neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols; and to receive a subframe from a sequence of subframes transmitted by the neighboring cell node; and
a processor, coupled to the transceiver, configured to determine that the received subframe is the multicast subframe based on the subframe sequence pattern; and to perform a single reference symbol measurement in response to determining that the received subframe is the multicast subframe.

### Claim 15 (depends on 14)

The apparatus of claim 14 further comprising a processor, coupled to the transceiver, configured to determine that the received subframe is the unicast subframe based on the subframe sequence pattern; and to perform at least one measurement based on at least two symbol bearing cell-specific reference symbols in response to determining that the received subframe is the unicast subframe.

### Claim 16

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving a subframe sequence pattern from a node in the communication network, the subframe sequence pattern indicates a type of subframe being transmitted by a neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node;
determining that the received subframe is the multicast subframe based on the subframe sequence pattern; and
performing a single reference symbol measurement in response to determining that the received subframe is the multicast subframe.

### Claim 17

A method in a mobile device for mobility measurements in a communication network, the method comprising:
receiving an indicator from a serving cell node, wherein the indicator indicates a type of subframe being transmitted by at least one neighboring cell node, wherein the type of subframe includes a unicast subframe comprising at least two orthogonal frequency division multiplexing (OFDM) symbol bearing cell-specific reference symbols, and a multicast subframe comprising at least one OFDM symbol bearing reference symbols;
receiving a subframe from a sequence of subframes transmitted by the neighboring cell node;
determining that the received subframe is the multicast subframe based on the received indicator; and
performing a single reference symbol measurement in response to determining that the received subframe is the multicast subframe.

### Claim 18 (depends on 17)

The method of claim 17, wherein determining that the received subframe is the multicast subframe comprises:
extracting a binary value from the received indicator;
considering at least one neighboring cell node transmits at least one multicast subframe when the extracted binary value is a first binary value;
ascertaining that the received subframe is the multicast subframe in response to considering at least one neighboring cell node transmits at least one multicast subframe.