U.S. patent application number 14/797941 was filed with the patent office on 2016-01-21 for device to device communication with cluster coordinating.
The applicant listed for this patent is INTEL IP CORPORATION. Invention is credited to KAMRAN ETEMAD, QINGHUA LI, HUANING NIU, HUJUN YIN.
Application Number | 20160021526 14/797941 |
Document ID | / |
Family ID | 51391685 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160021526 |
Kind Code |
A1 |
NIU; HUANING ; et
al. |
January 21, 2016 |
DEVICE TO DEVICE COMMUNICATION WITH CLUSTER COORDINATING
Abstract
Technology for a user equipment (UE) to communicate in a device
to device (D2D) network. A D2D discovery beacon can be listened for
at the UE for a predetermined period of time. The UE can be
self-assigned as a D2D cluster coordinator when the D2D discovery
beacon has not been received by the UE for the predetermined period
of time. A D2D cluster can be formed to enable D2D communication
between D2D UEs in the D2D cluster. A D2D discovery beacon can be
transmitted from the D2D cluster coordinator to the D2D UEs within
the D2D cluster.
Inventors: |
NIU; HUANING; (Milpitas,
CA) ; YIN; HUJUN; (Saratoga, CA) ; LI;
QINGHUA; (San Ramon, CA) ; ETEMAD; KAMRAN;
(Potomac, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTEL IP CORPORATION |
Santa Clara |
CA |
US |
|
|
Family ID: |
51391685 |
Appl. No.: |
14/797941 |
Filed: |
December 20, 2013 |
PCT Filed: |
December 20, 2013 |
PCT NO: |
PCT/US2013/077120 |
371 Date: |
July 13, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61768330 |
Feb 22, 2013 |
|
|
|
Current U.S.
Class: |
370/230 |
Current CPC
Class: |
H04W 28/0289 20130101;
H04W 76/28 20180201; H04W 72/0446 20130101; Y02D 30/70 20200801;
H04L 12/4633 20130101; H04L 47/11 20130101; H04L 61/2575 20130101;
H04W 72/0413 20130101; H04L 61/2564 20130101; H04L 45/30 20130101;
H04L 61/2539 20130101; H04W 74/002 20130101; H04W 36/30 20130101;
H04W 48/18 20130101; H04L 61/2525 20130101; H04W 72/02 20130101;
H04W 76/23 20180201; H04L 27/2614 20130101; H04W 4/70 20180201;
H04W 28/12 20130101; H04W 48/08 20130101; H04W 72/005 20130101;
H04W 72/042 20130101; H04W 36/0088 20130101; H04W 84/12 20130101;
H04L 47/12 20130101; H04W 48/14 20130101; H04W 48/16 20130101; H04W
4/80 20180201; H04W 88/06 20130101; H04W 8/005 20130101; H04W 76/27
20180201; H04W 24/02 20130101; H04W 52/028 20130101; H04L 61/6077
20130101; H04W 28/02 20130101; H04W 40/02 20130101; H04W 40/244
20130101; H04W 74/02 20130101; H04L 61/2592 20130101; H04W 28/08
20130101; H04W 74/04 20130101; H04W 74/08 20130101; H04W 76/14
20180201; H04L 61/2514 20130101; H04W 24/06 20130101; H04W 52/0216
20130101 |
International
Class: |
H04W 8/00 20060101
H04W008/00; H04W 24/02 20060101 H04W024/02; H04W 48/18 20060101
H04W048/18; H04W 28/02 20060101 H04W028/02; H04W 4/00 20060101
H04W004/00 |
Claims
1. A user equipment (UE) operable to communicate in a device to
device (D2D) network, having computer circuitry configured to:
listen for a D2D discovery beacon at the UE for a predetermined
period of time; self-assign the UE as a D2D cluster coordinator
when the D2D discovery beacon has not been received by the UE for
the predetermined period of time; form a D2D cluster to enable D2D
communication between D2D UEs in the D2D cluster; and transmit a
D2D discovery beacon from the D2D cluster coordinator to the D2D
UEs within the D2D cluster.
2. The computer circuitry of claim 1, wherein the computer
circuitry is further configured to: receive a join request at the
D2D cluster coordinator from a D2D UE in the D2D cluster to join
the D2D cluster; and communicate a join request approval to the D2D
UE.
3. The computer circuitry of claim 1, wherein the computer
circuitry is further configured to: receive a D2D bandwidth
allocation request for bandwidth from at least one D2D UE in the
D2D cluster; schedule a communication period for the at least one
D2D UE in the D2D cluster; and transmit scheduling information for
the communication period to the at least one D2D UE in the D2D
cluster to enable the at least one D2D UE to determine when the
bandwidth is allocated for the at least one D2D UE to communicate
with another D2D UE in the D2D cluster.
4. The computer circuitry of claim 1, wherein the computer
circuitry is further configured to coordinate scheduling
information of each of the D2D UEs in the D2D cluster to reduce
interference between the D2D UEs.
5. A user equipment (UE) operable to communicate in a device to
device (D2D) network, having computer circuitry configured to:
receive, at the UE, a D2D discovery beacon from a D2D UE
coordinator in a D2D communication cluster; transmit a join request
to the D2D UE coordinator, to join the D2D communication cluster;
and receive a join request approval message to join the D2D
communication cluster.
6. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to: transmit a D2D bandwidth
allocation request to the D2D UE coordinator in the D2D
communication cluster; receive a scheduling information from the
D2D UE coordinator for communicating with a D2D UE in the D2D
communication cluster; and transmit data from the UE to the D2D UE
in the D2D communication cluster at a selected time based on the
received scheduling information.
7. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to transmit a join request to an
adjacent D2D UE coordinator that is located in an adjacent D2D
communication cluster to the D2D communication cluster.
8. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to send a multicast transmission
request to the D2D UE coordinator to schedule a multicast by the UE
to other UEs in the D2D communication cluster.
9. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to request to associate or request
to dissociate with the D2D UE coordinator based on a receiving
power of the D2D discovery beacon at the UE.
10. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to request a handover from the D2D
UE coordinator to an other D2D UE coordinator based on a receiving
power of the D2D discovery beacon at the UE.
11. The computer circuitry of claim 5, wherein the computer
circuitry is further configured to receive D2D discovery beacons at
the UE from a plurality of D2D UE coordinators, wherein each D2D UE
coordinator is located in a separate D2D communication cluster.
12. An enhanced node B (eNB) operable to form a device to device
(D2D) communication cluster, having computer circuitry configured
to: receive a D2D cluster coordinator self-assignment request from
a user equipment (UE) at an enhanced node B (eNB); transmit a D2D
cluster coordinator assignment acceptance from the eNB to the UE to
form a D2D cluster coordinator UE; and form a D2D cluster by the
eNB to enable D2D communication between D2D UEs, wherein the D2D
cluster coordinator UE coordinates the D2D communication between
the D2D UEs in the D2D cluster.
13. The computer circuitry of claim 12, wherein the computer
circuitry is further configured to: receive a D2D radio bearer
setup request from an other UE in the D2D cluster at the eNB; and
establish a D2D radio bearer for a D2D pair that includes the other
UE.
14. The computer circuitry of claim 13, wherein the computer
circuitry is further configured to establish the D2D radio bearer
to provide a desired quality of service (QoS).
15. The computer circuitry of claim 12, wherein the computer
circuitry is further configured to determine a D2D cluster
coordinator UE in the D2D cluster to receive the D2D cluster
coordinator assignment based on a power capacity level or a battery
capacity level threshold of the UE in the D2D cluster.
16. The computer circuitry of claim 15, wherein the computer
circuitry is further configured to transmit a D2D cluster
coordinator assignment acceptance to a first UE in the D2D cluster
that sends the D2D cluster coordinator self-assignment request and
the power capacity level or the battery capacity level is above the
threshold.
17. The computer circuitry of claim 12, wherein the computer
circuitry is further configured to enable a hand over of a D2D UE
in the D2D cluster to an other D2D cluster coordinator in an other
D2D cluster.
18. The computer circuitry of claim 12, wherein the computer
circuitry is further configured: receive a cluster association
request at the eNB from an other UE to join the D2D cluster; and
communicate, to the D2D cluster coordinator UE, a cluster
association approval for the other UE to associate with the D2D
cluster coordinator UE to join the D2D cluster.
19. The computer circuitry of claim 12, wherein the computer
circuitry is further configured to receive, at the eNB, a cluster
information message from the D2D cluster coordinator UE, wherein
the cluster information message includes: a D2D bandwidth request
for D2D communication by UEs in the D2D cluster; an interference
report, regarding interference between the UEs in the D2D cluster
or interference between UEs in adjacent D2D clusters; a transmit
power control message; a request to move a D2D communication
frequency to a different frequency band; a request to add an other
UE to the D2D cluster; or a request to remove at least one UE from
the D2D cluster.
20. The computer circuitry of claim 12, wherein the computer
circuitry is further configured to use the interference report, by
the eNB, to determine when to combine or split D2D clusters.
21. A method for forming a device to device (D2D) communication
cluster, comprising: searching, by a user equipment (UE), for a D2D
discovery beacon communicated from a D2D cluster coordinator;
transmitting a D2D cluster coordinator self-assignment request from
the UE to an enhanced node B (eNB) when the D2D discovery beacon is
not received for a selected period of time; receiving a D2D cluster
coordinator self-assignment request approval from the eNB to
configure the UE as a D2D cluster coordinator; and forming a D2D
cluster by the D2D cluster coordinator to enable D2D communication
between UEs in the D2D cluster.
22. The method of claim 21, further comprising: transmitting a D2D
discovery beacon to the UEs located within a coverage area of the
D2D cluster; and receiving a join request from at least one of the
UEs to join the D2D cluster.
23. The method of claim 22, further comprising communicating a join
request approval from the D2D cluster coordinator to the at least
one UE.
24. The method of claim 21, further comprising: communicating to
the eNB the join request of the at least one UE from the D2D
cluster coordinator; and receiving a join request approval from the
eNB at the D2D cluster coordinator for the at least one UE to join
the D2D cluster.
25. The method of claim 21, further comprising: receiving a D2D
bandwidth allocation request from at least one UE in the D2D
cluster; scheduling bandwidth for the at least one UE; and
transmitting a D2D bandwidth allocation message to the at least one
UE within the D2D cluster to enable the at least one UE to
determine when bandwidth is allocated for the at least one UE to
communicate with another UE in the D2D cluster.
26. The method of claim 21, further comprising the cluster
coordinator serving as a mobile Pico node.
27. The method of claim 26, further comprising dynamically
optimizing the location and coverage of the mobile Pico node based
on D2D traffic.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of and hereby
incorporates by reference U.S. Provisional Patent Application Ser.
No. 61/768,330, filed Feb. 22, 2013, with an attorney docket number
P54652Z.
BACKGROUND
[0002] Users of wireless and mobile networking technologies are
increasingly using their mobile devices to communicate as well as
send and receive data. With increased data communications on
wireless networks, the strain on the limited resources for
telecommunications is also increasing.
[0003] To handle the increasing amount of wireless services for an
increasing numbers of users, efficient use of the available radio
network resources has become important. Device to Device (D2D)
communications allows mobile users to directly communicate with
each other with little or no burden on a wireless network. The D2D
communication can occur when adjacently located devices are enabled
to communicate with each other directly instead of using a
conventional communications links such as a Wi-Fi or cellular
communications system. D2D communications may occur within range of
a cellular communications system, such as an enhanced node B (eNB).
The cellular communication system can assist with the D2D
communication.
[0004] D2D communications can also occur outside of the range of a
cellular communications system or where a cellular communications
system is unavailable, e.g. non-network assisted. In either case,
network-assisted or non-network assisted D2D communications can be
coordinated to achieve higher spatial reuse, manage interference,
and limit control and feedback overhead.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Features and advantages of the disclosure will be apparent
from the detailed description which follows, taken in conjunction
with the accompanying drawings, which together illustrate, by way
of example, features of the disclosure; and, wherein:
[0006] FIG. 1 depicts a D2D communication centralized scheduling
scheme in accordance with an example;
[0007] FIG. 2 shows a downlink radio frame structure in accordance
with an example;
[0008] FIG. 3 depicts a network-assisted cluster based architecture
in accordance with an example;
[0009] FIG. 4 illustrates a non-network assisted cluster based
architecture in accordance with an example;
[0010] FIG. 5 illustrates a self-elected cluster coordinator
discovering D2D devices in a D2D cluster in accordance with an
example;
[0011] FIG. 6 shows a core network server or D2D server setting up
a D2D radio bearer to pair D2D UEs together in accordance with an
example;
[0012] FIG. 7 depicts a bandwidth allocation scheme for a
network-assisted cluster based architecture in accordance with an
example;
[0013] FIG. 8 depicts a bandwidth allocation scheme for a
non-network assisted cluster based architecture in accordance with
an example;
[0014] FIGS. 9a and 9b show examples of frame and symbol structures
using a D2D subframe structure in accordance with an example;
[0015] FIG. 10 depicts the functionality of computer circuitry with
a UE operable to communicate in a D2D network in accordance with an
example;
[0016] FIG. 11 depicts the functionality of computer circuitry with
a UE operable to communicate in a D2D network in accordance with an
example;
[0017] FIG. 12 depicts the functionality of computer circuitry with
an enhanced node B (eNB) operable to form a D2D communication
cluster in accordance with an example;
[0018] FIG. 13 illustrates a method for forming a D2D communication
cluster in accordance with an example;
[0019] FIG. 14 illustrates a diagram of a UE in accordance with an
example.
[0020] Reference will now be made to the exemplary embodiments
illustrated, and specific language will be used herein to describe
the same. It will nevertheless be understood that no limitation of
the scope of the invention is thereby intended.
DETAILED DESCRIPTION
[0021] Before the present invention is disclosed and described, it
is to be understood that this invention is not limited to the
particular structures, process steps, or materials disclosed
herein, but is extended to equivalents thereof as would be
recognized by those ordinarily skilled in the relevant arts. It
should also be understood that terminology employed herein is used
for the purpose of describing particular examples only and is not
intended to be limiting. The same reference numerals in different
drawings represent the same element. Numbers provided in flow
charts and processes are provided for clarity in illustrating steps
and operations and do not necessarily indicate a particular order
or sequence.
[0022] Direct communication between mobile wireless devices that
are located close to or adjacent each other can be advantageous to
alleviate the signaling overhead and signal interference between
devices and nodes in a cellular network. Device to device (D2D) or
machine type communication refers to direct communication among
devices or machines without routing the data through a
communications network, such as a cellular network or a wireless
fidelity (WiFi) network.
[0023] Clustering closely located D2D devices, such as user
equipments (UEs) that are capable of D2D or local communication is
a feasible and efficient way of increasing data demands on cellular
networks while alleviating signaling overhead and managing
interference. In D2D communication, devices can be grouped into
clusters, where at least one device sends data to another device in
a cluster. A cluster can comprise multiple D2D devices that are
located nearby or adjacent each other. A cluster can also comprise
multiple D2D devices that can locally communicate with other D2D
devices directly. A cluster can also comprise grouping together D2D
devices with mutual or similar properties or characteristics.
[0024] The D2D devices in a cluster can be grouped into clusters
based on the relative location of a D2D UE to other D2D UEs or
based on other criteria, such as similar data requirements. D2D
devices in a cluster can directly share the resources with other
D2D devices. In one embodiment, D2D devices in a cluster can share
resources by competing for allocated resources. In another
embodiment, D2D device in a cluster can directly share resources by
having one of the D2D devices allocate the resources. In one
embodiment the resources may be allocated between cluster members
based on a resource allocation grant by the cellular network. In
one embodiment, the resources may also be allocated independent of
a cellular network and be allocated using a D2D cluster
coordinator.
[0025] In a D2D communications system there are several D2D
communication system schemes where multiple mobile equipment
devices, such as UE, can directly communicate with each other
and/or communicate with a cellular communications system, such as
an enhanced node B (eNB) or base station.
[0026] One D2D communication system scheme is an in-network or
network assisted scheme that has a central controller, such as an
eNB or a base station, receiving transmission requests from all the
UEs in the D2D communications system. In another embodiment, a D2D
communications system can be integrated into a cellular network,
where an eNB can allocate resources for the cluster and a D2D
coordinator then allocates the resources to each cluster member,
such as each D2D device. In another embodiment, the D2D coordinator
can assign subsets of resources to nearby devices in a cluster.
[0027] The cellular communications system can comprise one or more
cellular network nodes and one or more Institute of Electrical and
Electronics Engineers (IEEE) 802.11-2012 configured access points.
In one embodiment, the one or more cellular networks may be 3rd
generation partnership project (3GPP) long term evolution (LTE)
Rel. 8, 9, 10, or 11 networks and/or IEEE 802.16p, 802.16n,
802.16m-2011, 802.16h-2010, 802.16j-2009, 802.16-2009 networks.
[0028] The D2D coordinator collects all the D2D communication
requests within the cluster. The cellular network node can take all
the requests from UE coordinators within the cell. The cellular
network node can semi-statically allocate a large amount of
resources per cluster. The cluster coordinator can be responsible
for resource allocation of each D2D pair within the cluster. One
advantage of a two tier resource allocation, where the D2D
coordinator and the cellular network node allocate resources, is
that the two tier resource allocation can dramatically reduced the
signaling overhead from the cellular network node and reduce the
feedback overhead from UE to cellular network node.
[0029] When D2D communication takes place within a cellular
network, the cluster can operate on uplink (UL) or downlink (DL)
resources. For UL resources, an UL resource allocation grant can be
reused for network controlled cluster operation. The
network-assisted cluster scheduling operation can lower the
threshold for adapting user cooperation schemes between D2D capable
UEs or other types of mobile users and can help to permit efficient
data transfer between cluster members.
[0030] FIG. 1 illustrates one embodiment of a D2D communication
centralized scheduling scheme that has a central controller, such
as eNB or a base station. The centralized controller 110 in the
centralized scheduling scheme can comprise a transceiver 120 and a
computer processor 130. FIG. 1 also illustrates that the UE 140 can
comprise a transceiver 150 and a computer processor 160.
[0031] D2D communication systems may provide mobile device users
with better quality of service (QoS), new applications, and
increased mobility support. To increase efficiency and reduce
interference, UEs in a D2D system can synchronize their D2D
communications. In one example, the UEs synchronize within the D2D
network using a radio frame structure, transmitted on a physical
(PHY) layer in a DL or UL transmission between an eNB and a D2D UE.
In one embodiment, the D2D communications may occur on a licensed
band for communications. In one embodiment a 3GPP LTE frame
structure is used for the synchronization. In one embodiment, the
one or more cellular networks may a 3GPP LTE Rel. 8, 9, 10, 11, or
12 network and/or a IEEE 802.16p, 802.16n, 802.16m-2011,
802.16h-2010, 802.16j-2009, 802.16-2009.
[0032] FIG. 2 illustrates a downlink radio frame structure. In
another embodiment, an uplink radio frame structure could similarly
be used. In the example of the downlink radio frame structure, a
radio frame 200 of a signal used to transmit the data can be
configured to have a duration, Tf, of 10 milliseconds (ms). Each
radio frame can be segmented or divided into ten subframes 210i
that are each 1 ms long. Each subframe can be further subdivided
into two slots 220a and 220b, each with a duration, Tslot, of 0.5
ms. The first slot (#0) 220a can include a legacy physical downlink
control channel (PDCCH) 260 and/or a PDSCH 266, and the second slot
(#1) 220b can include data transmitted using the PDSCH. Additional
structures may also be used, such as enhanced structures for
enhanced PDCCH (ePDCCH) or other types of enhanced channels.
[0033] Each slot for a component carrier (CC) used by the node and
the wireless device can include multiple RBs 230a, 230b, 230i,
230m, and 230n based on the CC frequency bandwidth. Each RB
(physical RB or PRB) 230i can include 12-15kHz subcarriers 236 (on
the frequency axis) and 6 or 7 orthogonal frequency-division
multiplexing (OFDM) symbols 232 (on the time axis) per slot. The RB
can use seven OFDM symbols if a short or normal cyclic prefix is
employed. The RB can use six OFDM symbols if an extended cyclic
prefix is used. The RB can be mapped to 84 resource elements (REs)
240i using short or normal cyclic prefixing, or the RB can be
mapped to 72 REs (not shown) using extended cyclic prefixing. The
RE can be a unit of one OFDM symbol 242 by one subcarrier (i.e., 15
kHz) 246.
[0034] When communicating with each other, each D2D UE may need to
switch between transmission and reception modes for sending and
receiving messages, respectively. In one embodiment, D2D
communications can be performed during the UL band communications
period of a cellular network. In this embodiment, the sequential
switching between the transmission and reception modes may enable
UEs to perform D2D communications during the UL band communications
period of a cellular network. In another embodiment, D2D
communications may be performed during the DL band communications
period of a cellular network. In this embodiment, the sequential
switching between the transmission and reception modes may enable
UEs to perform D2D communications during a DL band communications
period of a cellular network.
[0035] FIG. 3 shows multiple mobile devices or UEs 340, 350, and
360 located nearby or adjacent each other which can be assigned or
formed into D2D clusters. In one embodiment, if a D2D UE wants to
start the D2D communication, after the D2D discovery process, the
D2D UE will scan for a D2D cluster discovery beacon to determine
whether there is an existing D2D cluster within range of the D2D
UE. If the D2D UE cannot find an existing cluster, the D2D UE wants
to start a D2D cluster and the D2D UE can send a forming cluster
request message to the eNB 330. When the D2D UE receives a grant
from the eNB 330, the D2D UE can start a D2D cluster discovery
beacon. Nearby D2D pairs that detect the cluster beacon can join
the cluster. This may be desirable in a case of a D2D cluster
operation in which the cluster comprises more than two locally
communicating devices or UEs.
[0036] FIG. 3 also illustrates one embodiment of a network-assisted
cluster based architecture with a UE coordinator. In a
network-assisted cluster based architecture, multiple D2D UEs 340,
350, and 360 can be assigned or formed into D2D clusters. One of
the D2D UEs may serve as a cluster coordinator 360, coordinating
the channel accesses of the D2D UEs 340, 350, and 360. In one
embodiment, the D2D UEs can be assigned as pairs for D2D
communication, such as a transmitter D2D UE 340 and receiver D2D UE
350. In one embodiment, D2D UEs 340, 350, 360, and/or 390 and eNB
330 can work together to determine if the cluster should be formed
and which UE is the cluster coordinator 360. In one embodiment, the
eNB 330 can form the clusters 310, 320, 370, and 380 based on the
approximate location of each UE in the network. In one embodiment,
if D2D UEs 390 are not located within a defined distance or signal
strength of each other, a cluster may not be formed and the UEs 390
can communicate with other UEs via the eNB 330.
[0037] In one embodiment where clusters 370 and 380 overlap, the
eNB can assign different resource blocks to each of the overlapping
clusters. For example if cluster 1 (370) and cluster 2 (380)
overlap, the eNB can assign RBs 1 through 10 to overlapping cluster
1 (370) and RBs 11 through 20 to overlapping cluster 2 (380). In
another embodiment where clusters 310 and 320 do not overlap, the
eNB can reuse the same RBs and assign RBs 1 through 20 to each of
the non-overlapping clusters.
[0038] In one embodiment, selected UEs can be assigned as high
category UEs. High category UEs are UEs that have some increased or
additional functionality beyond the normal functionality of a UE in
order to be a cluster coordinator. In one embodiment, only high
category UEs may be assigned as a cluster coordinator 360. For
example, a D2D UE with a battery level capacity that exceeds a
selected threshold may be assigned as a high category UE. In one
embodiment, the high category UEs can self-elect to be a cluster
coordinator. In one embodiment, the eNB can ratify the first D2D UE
that volunteers to be the cluster coordinator with a battery level
capacity that exceeds a selected threshold for a cluster
coordinator. In one embodiment, the cluster coordinator may not be
involved in any D2D communication and may only be facilitator.
[0039] FIG. 4 illustrates a non-network assisted cluster based
architecture 400 with a cluster coordinator 460. In a non-network
assisted cluster based architecture, multiple D2D UEs 440, 450, and
460 can be assigned or formed into D2D clusters. One of the D2D UEs
may serve as a cluster coordinator 460, coordinating the channel
accesses of the D2D UEs 440, 450, and 460. In one embodiment, the
D2D UEs can be assigned as pairs for D2D communication, such as a
transmitter (Tx) D2D UE 440 and receiver (Rx) D2D UE 450. In one
embodiment, D2D UEs 440, 450, 460, and/or 430 can work together to
decide if a cluster should be formed and which D2D UE is assigned
or selected as the cluster coordinator 460. In one embodiment, each
cluster coordinator can form a cluster, such as clusters 410, 420,
470, and 480 respectively based on the approximate location of each
D2D UE in the network. In one embodiment, if D2D UEs 490 are not
located within a defined distance or signal strength of other D2D
UEs, a cluster may not be formed and the D2D UEs 430 can
communicate directly or indirectly with one or more clusters 410,
420, 470, and/or 480. In one embodiment, a D2D pair 440 and 450 can
belong to multiple clusters, such as overlapping cluster 1 (470)
and overlapping cluster 2 (480). In another embodiment, a D2D pair
440 and 450 can belong to choose one cluster to join from a
plurality of clusters such as overlapping cluster 1 (470) and
overlapping cluster 2 (480).
[0040] In one embodiment, a UE can self-elect as a coordinator,
such as a D2D coordinator, cluster coordinator, or UE coordinator.
To determine if a cluster coordinator is needed, the UE may listen
for a selected period of time for a discovery beacon from another
D2D UE. When the
[0041] UE does not hear or receive a discover beacon within the
selected period of time, the UE can elect itself as the cluster
coordinator.
[0042] In one embodiment, the UE can assess if the UE meets the
cluster coordinator requirements before electing itself as cluster
coordinator. In one embodiment, the cluster coordinator
requirements may include a battery capacity level threshold or a
transmit power threshold. In another embodiment, if the UE meets
the cluster coordinator requirements then the UE can elect itself
as the cluster coordinator. In one embodiment, the cluster
coordinator can determine the size of the cluster. The size of the
cluster may be determined based on a coverage range of the cluster
coordinator. In one embodiment the coverage range can be based on
the power level of the cluster coordinator.
[0043] FIG. 5 illustrates that when a cluster coordinator 560 has
been selected or self-elected, the cluster coordinator 560 can
broadcast a discovery beacon 570 to be received by adjacent D2D
UEs, such as D2D UEs 510-550, to discover the D2D devices in a D2D
cluster. In one embodiment, the cluster coordinator 560 can receive
requests to join the D2D cluster from UEs outside of the D2D
cluster. In one embodiment, the discovery beacon sent by the
cluster coordinator 560 can be a reserved set of sequences out of
the total set of discovery sequences. In another embodiment, the
discovery beacon can also be a short data packet. The short data
packet can include the cluster coordinator's identification (ID)
and information related to forming a cluster. In one embodiment,
the cluster discovery beacon may be sent at selected time periods
or at regular intervals. In one embodiment, a D2D UE such as D2D
UEs 510-550 can use the receive power of the discovery beacon as a
reference to determine D2D UE cluster association, cluster
dissociation, and cluster handover decisions. In one embodiment,
the cluster coordinator can assign RBs to the cluster to reduce or
eliminate interference between UEs in the cluster and with UEs in
adjacent clusters.
[0044] In one embodiment, when a D2D UE moves out of the range of
the cluster coordinator 560, dissociation can occur. For example, a
D2D UE associated with a cluster may monitor the received discovery
beacon power. If the received beacon power drops below a selected
level or threshold, the D2D UE may dissociate with the cluster. In
another embodiment, a cluster handover, such as a handover of a D2D
communication back to an uplink transmission, is performed by a
core network or eNB. In one embodiment, a core network server or
D2D server can control the handover between D2D transmission and
normal UL transmission. For a non-network assisted cluster based
architecture, a core network server or D2D server may not be used
because all safety related information is broadcasted and each D2D
UE has the same QoS.
[0045] In one embodiment, the association of a D2D UE with a
cluster coordinator may be assisted by an eNB. For example, a D2D
UE who can receive the discovery beacon and is not a member of the
cluster may send an acknowledgment message to an eNB and the eNB
will relay the acknowledgment message to the cluster coordinator.
In another embodiment, the association of a D2D UE with a cluster
coordinator 560 may be non-network assisted. For example, a D2D UE
that is not a member of the cluster can receive the discovery
beacon and directly send an acknowledgment message to the cluster
coordinator.
[0046] An acknowledgement message may have several different
formats. In one embodiment, the acknowledgement message is a
physical layer acknowledgement (PHY ACK). For a PHY ACK, a D2D UE
can simply reply back with a beacon at certain time/frequency
slots. In another embodiment, the acknowledgement message is a
medium access control (MAC) packet. For a MAC packet, the D2D UE
will send the acknowledgement message as a payload and transmit the
acknowledgement message through a random access channel. In one
example, a D2D UE that desires to join a cluster may not send an
ACK to the cluster coordinator directly. Instead, the UE can send a
request to the eNB for criteria matching. If the selected criteria
are matched, the eNB may let the cluster coordinator and the D2D UE
know that the D2D UE desires to join the cluster, at which point
further association steps can be performed.
[0047] FIG. 5 further illustrates that a D2D UE may listen for
and/or receive multiple discovery beacons and may identify multiple
nearby or adjacent clusters. The D2D UE can select one or more
clusters to associate with. When a D2D UE, such as Tx D2D UEs and
Rx D2D UEs 510-550, select a cluster to associate with, each D2D UE
can send a join request 580 to the cluster coordinator 560
requesting to join the cluster.
[0048] In one embodiment, each cluster has one cluster coordinator
560. In another embodiment, the cluster coordinator assignment or
role may alternate between multiple UEs over a period of time. One
advantage to alternating which UE is the cluster coordinator 560 is
that the UEs that are cluster coordinators 560 for a period of time
can save power during the period that the UE is not the cluster
coordinator 560. In another embodiment, the cluster coordinator 560
may alternate to another UE when the current cluster coordinator's
battery level falls below a selected threshold. In one embodiment,
to alternate the cluster coordinator assignment, the current
cluster coordinator and the UE that want to be the next cluster
coordinator, e.g. the future cluster coordinator, can alternate or
switch the cluster coordinator role using D2D broadcast
communication.
[0049] A non-network assisted D2D communications system can be
advantageous for a public safety usage situation. In one
embodiment, a cluster coordinator can serve as a mobile Pico node.
In one embodiment, the location and coverage of the mobile Pico
node is dynamically optimized based on D2D traffic. In another
embodiment, the cluster coordinator can be a D2D UE with a battery
capacity level that is higher than a selected threshold.
[0050] In a network-assisted environment, the cluster coordinator
can communicate with eNB to: request or release D2D bandwidth for
the whole cluster; report interference among clusters for combing
or splitting the cluster; request to change the transmit power;
request to move to a different frequency band; or request to add or
remove a D2D UE to or from the cluster. In a non-network assisted
environment, the cluster coordinators between different clusters
can directly: request or release D2D bandwidth for the whole
cluster; report interference among clusters for combing or
splitting the cluster; request to change the transmit power;
request to move to a different frequency band; or request to add or
remove a D2D UE to or from the cluster. For overlapping clusters a
D2D UE can determine which cluster is best or join multiple
clusters.
[0051] FIG. 6 illustrates that for a network-assisted cluster based
architecture 600, a core network server or D2D server can set up a
D2D radio bearer to pair D2D UEs and to ensure quality of service
(QoS) control. The eNB and/or the core network can set up the D2D
UE data communication radio bearer. In one embodiment, a radio
bearer is a link between two points that meet a defined or selected
characteristic. In one embodiment, a selected characteristic is the
proximity of D2D UEs, such as D2D UE pairs 610 and 620, 630 and
640, or 650 and 660. In one embodiment, for a UE associated with a
radio bearer, the radio bearer can specify a configuration for
layer 2 and physical layer communication in order to have its QoS
clearly defined. In another embodiment, radio bearers are layer 2
or higher for the transfer of either the UE data or control
data.
[0052] In one embodiment, if a cluster coordinator discovers that a
D2D UE pair is within direct communication range, then the cluster
coordinator can send a request to the eNB and core network to
request the setup of a radio bearer and corresponding QoS. In
another embodiment, a corresponding D2D radio network temporary
identifier (RNTI) can also be granted for D2D communication. In one
embodiment, the D2D RNTI is sent to both the transmitter D2D UE and
the receiver D2D UEs such that the Rx D2D UE knows it is the
addressed or receiving D2D UE for D2D communication.
[0053] FIG. 7 illustrates a network-assisted cluster based
architecture where a Tx D2D UE, such as Tx D2D UEs 720, 730, and
760, has data to communicate to an Rx D2D UE, such as Rx D2D UEs
740, 750 or 710. When the Tx D2D UE has data to communicate, the Tx
D2D UE will send a bandwidth request 770 to the eNB 700 and the UE
coordinator 710. The bandwidth request 770 can be a contention
based transmission in the bandwidth request zone. Bandwidth request
770 may consist of two portions, a contention code or preamble and
a request message payload. The contention code can be used as a
channel training signal for detecting a request message. When a
collision occurs, the coordinator may still be able to detect
multiple collided contention codes though the collided request
messages may be lost. If the request message is successfully
decoded, the coordinator may grant the resource. If the request
message is lost but the code is detected, the coordinator may ask
the transmitter which sent the code to submit the request message
in an allocated resource.
[0054] If bandwidth is allocated by the UE coordinator 710 for
multiple transmissions by a Tx D2D UE 720, 730, or 760 to Rx D2D
UEs 710, 740, or 750, the D2D UE receivers may receive a bandwidth
allocation grant 780 from the eNB 700 and/or the UE coordinator 710
that includes a notification of the multiple transmissions
bandwidth allocation grant.
[0055] FIG. 8 illustrates a non-network assisted cluster based D2D
communications architecture. In the non-network assisted cluster
based D2D communications architecture the UE coordinator 810
coordinates communications between D2D UEs 810-860 within the
cluster. To coordinate D2D communications between D2D UEs 810-860,
the UE coordinator 810 can receive bandwidth requests 870 from Tx
D2D UEs 810, 830, and 860 within the cluster and broadcast resource
allocations 880 to D2D UEs in the cluster. In one embodiment, Tx
D2D UEs 810, 830, and/or 860 send a bandwidth request 870 to the UE
coordinator 810. The UE coordinator 810 can receive the bandwidth
request from the D2D transmitter 810, 830, and/or 860 and can
allocate bandwidth for the D2D transmission. The UE coordinator 810
can communicate a bandwidth allocation grant 880 to D2D UEs 820-860
in the cluster. In one embodiment, the bandwidth allocation grant
may be unicast to a Tx D2D UE and a RX D2D UE pair. In one
embodiment, only the Tx D2D UE and the Rx D2D UE pair, such as
pairs 810 and 820, 830 and 840, or 850 and 860, can decode the
bandwidth allocation grant. In another embodiment, the UE
coordinator 810 may broadcast the allocation grants to the D2D UEs
within the cluster. In one embodiment, a Tx D2D UE may request
resources or bandwidth for multicast transmissions.
[0056] In one embodiment, the bandwidth allocation grant 880 can
include D2D communication scheduling information, including: when a
D2D UE pair can communicate data, the period of time the D2D UE
pair can communicate for, and/or the amount of bandwidth allocated
for the D2D communication. The scheduling information can be
applied in a future subframe, e.g. the next subframe, of the
bandwidth allocation grant. In one embodiment, a D2D data
communication uses an UL carrier or UL subframes in a time division
duplex (TDD) system. In another embodiment, a transmitted waveform
can follow either a DL frequency division multiple access (OFDMA)
waveform or UL single carrier frequency division multiple access
(SCFDMA) waveform. One advantage of using a DL OFDMA waveform is a
reduction in UE implementation complexity because the D2D reception
can share the hardware of the normal downlink.
[0057] FIGS. 9a and 9b show examples of frame structures and symbol
structures using a D2D subframe structure. The scheduling
information 950 is a communications schedule for D2D
communications. In one embodiment, a D2D subframe 3 is where data
transmission 960 occurs. In another embodiment, the RS can reuse DL
cell-specific reference signal (CRS) port 0 and port 1 for one or
two stream transmissions. In another embodiment, the CRS will also
be used for other measurements, such as D2D transmission power
control and adaptive coding and modulation. In one embodiment, the
contents in the scheduling information 950 can follow a current
downlink control information (DCI) or a simplified DCI for D2D
transmission. In one embodiment, the D2D subframe structure is a UL
subframe structure. In another embodiment, the D2D subframe
structure is a DL subframe structure. In one embodiment, the random
access zone 940 is a bandwidth request zone or a contentions zone
to request bandwidth from the cluster coordinator.
[0058] In one embodiment, the reference signal structure may be
different from the CRS since there is no periodic reference signal
sent on the link. In another embodiment, a reference symbol may be
used for OFDMA modulation. The reference symbol enables automatic
gain control (AGC) setting and channel estimation at the receiver
for burst traffic.
[0059] FIG. 10 provides a flow chart 1000 to illustrate the
functionality of one embodiment of the computer circuitry with a UE
operable to communicate in a D2D network. The functionality can be
implemented as a method or the functionality can be executed as
instructions on a machine, where the instructions are included on
at least one computer readable medium or one non-transitory machine
readable storage medium. The computer circuitry can be configured
to listen for a D2D discovery beacon at the UE for a predetermined
period of time, as in block 1010. The computer circuitry can be
further configured to self-assign the UE as a D2D cluster
coordinator when the D2D discovery beacon has not been received by
the UE for the predetermined period of time, as in block 1020. The
computer circuitry can also be configured to form a D2D cluster to
enable D2D communication between D2D UEs in the D2D cluster, as in
block 1030. The computer circuitry can also be configured to
transmit a D2D discovery beacon from the D2D cluster coordinator to
the D2D UEs within the D2D cluster, as in block 1040.
[0060] In one embodiment, the computer circuitry is further
configured to receive a join request at the D2D cluster coordinator
from a D2D UE in the D2D cluster to join the D2D cluster and
communicate a join request approval to the D2D UE. In another
embodiment, the computer circuitry is further configured to receive
a D2D bandwidth allocation request for bandwidth from at least one
D2D UE in the D2D cluster, schedule a communication period for the
at least one D2D UE in the D2D cluster, and transmit scheduling
information for the communication period to the at least one D2D UE
in the D2D cluster to enable the at least one D2D UE to determine
when the bandwidth is allocated for the at least one D2D UE to
communicate with another D2D UE in the D2D cluster. In another
embodiment, the computer circuitry is further configured to
coordinate scheduling information of each of the D2D UEs in the D2D
cluster to reduce interference between the D2D UEs.
[0061] FIG. 11 provides a flow chart 1100 to illustrate the
functionality of one embodiment of the computer circuitry with a UE
operable to communicate in a D2D network. The functionality can be
implemented as a method or the functionality can be executed as
instructions on a machine, where the instructions are included on
at least one computer readable medium or one non-transitory machine
readable storage medium. The computer circuitry can be configured
to receive, at the UE, a D2D discovery beacon from a D2D UE
coordinator in a D2D communication cluster, as in block 1110. The
computer circuitry can be further configured to transmit a join
request to the D2D UE coordinator, to join the D2D communication
cluster, as in block 1120. The computer circuitry can also be
configured to receive a join request approval message to join the
D2D communication cluster, as in block 1130.
[0062] In one embodiment, the computer circuitry is further
configured to transmit a D2D bandwidth allocation request to the
D2D UE coordinator in the D2D communication cluster, receive a
scheduling information from the D2D UE coordinator for
communicating with a D2D UE in the D2D communication cluster, and
transmit data from the UE to the D2D UE in the D2D communication
cluster at a selected time based on the received scheduling
information. In another embodiment, the computer circuitry is
further configured to transmit a join request to an adjacent D2D UE
coordinator that is located in an adjacent D2D communication
cluster to the D2D communication cluster. In another embodiment,
the computer circuitry is further configured to send a multicast
transmission request to the D2D UE coordinator to schedule a
multicast by the UE to other UEs in the D2D communication cluster.
In another embodiment, the computer circuitry is further configured
to request to associate or request to dissociate with the D2D UE
coordinator based on a receiving power of the D2D discovery beacon
at the UE. In one embodiment, the computer circuitry is further
configured to request a handover from the D2D UE coordinator to
another D2D UE coordinator based on a receiving power of the D2D
discovery beacon at the UE. In another embodiment, the computer
circuitry is further configured to receive D2D discovery beacons at
the UE from a plurality of D2D UE coordinators, wherein each D2D UE
coordinator is located in a separate D2D communication cluster.
[0063] FIG. 12 provides a flow chart 1200 to illustrate the
functionality of one embodiment of the computer circuitry with an
eNB operable to form a D2D communication cluster. The functionality
can be implemented as a method or the functionality can be executed
as instructions on a machine, where the instructions are included
on at least one computer readable medium or one non-transitory
machine readable storage medium. The computer circuitry can be
configured to receive a D2D cluster coordinator self-assignment
request from a UE at an eNB, as in block 1210. The computer
circuitry can be further configured to transmit a D2D cluster
coordinator assignment acceptance from the eNB to the UE to form a
D2D cluster coordinator UE, as in block 1220. The computer
circuitry can also be configured to form a D2D cluster by the eNB
to enable D2D communication between D2D UEs, as in block 1230. In
one embodiment, the D2D cluster coordinator UE coordinates the D2D
communication between the D2D UEs in the D2D cluster.
[0064] In one embodiment, the computer circuitry is further
configured to receive a D2D radio bearer setup request from another
UE in the D2D cluster at the eNB and establishing a D2D radio
bearer for a D2D pair that includes the other UE. In another
embodiment, the computer circuitry is further configured to
establish the D2D radio bearer to provide a desired quality of
service (QoS). In another embodiment, the computer circuitry is
further configured to determine a D2D cluster coordinator UE in the
D2D cluster to receive the D2D cluster coordinator assignment based
on a power capacity level or a battery capacity level threshold of
the UE in the D2D cluster. In another embodiment, the computer
circuitry is further configured to transmit a D2D cluster
coordinator assignment acceptance to a first UE in the D2D cluster
that sends the D2D cluster coordinator self-assignment request and
the power capacity level or the battery capacity level is above the
threshold. In one embodiment, the computer circuitry is further
configured to enable a hand over of a D2D UE in the D2D cluster to
an other D2D cluster coordinator in an other D2D cluster. In
another embodiment, the computer circuitry is further configured to
receive a cluster association request at the eNB from an other UE
to join the D2D cluster and communicating, to the D2D cluster
coordinator UE, a cluster association approval for the other UE to
associate with the D2D cluster coordinator UE to join the D2D
cluster.
[0065] In one embodiment, the computer circuitry is further
configured to receive, at the eNB, a cluster information message
from the D2D cluster coordinator UE, wherein the cluster
information message includes: a D2D bandwidth request for D2D
communication by UEs in the D2D cluster; an interference report,
regarding interference between the UEs in the D2D cluster or
interference between UEs in adjacent D2D clusters; a transmit power
control message; a request to move a D2D communication frequency to
a different frequency band; a request to add an other UE to the D2D
cluster; and/or a request to remove at least one UE from the D2D
cluster. In another embodiment, the computer circuitry is further
configured to use the interference report, by the eNB, to determine
when to combine or split D2D clusters.
[0066] FIG. 13 illustrates a method for forming a D2D communication
cluster. The method can comprise searching, by a user equipment
(UE), for a D2D discovery beacon communicated from a D2D cluster
coordinator, as in block 1310. The method can further comprise
transmitting a D2D cluster coordinator self-assignment request from
the UE to an eNB when the D2D discovery beacon is not received for
a selected period of time, as in block 1320. The method can also
comprise receiving a D2D cluster coordinator self-assignment
request approval from the eNB to configure the UE as a D2D cluster
coordinator, as in block 1330. The method may further comprise
forming a D2D cluster by the D2D cluster coordinator to enable D2D
communication between UEs in the D2D cluster, as in block 1340.
[0067] In one embodiment, the method further comprises transmitting
a D2D discovery beacon to the UEs located within a coverage area of
the D2D cluster and receiving a join request from at least one of
the UEs to join the D2D cluster. In another embodiment, the method
further comprises communicating a join request approval from the
D2D cluster coordinator to the at least one UE. In another
embodiment, the method further comprises communicating to the eNB
the join request of the at least one UE from the D2D cluster
coordinator and receiving a join request approval from the eNB at
the D2D cluster coordinator for the at least one UE to join the D2D
cluster. In another embodiment, the method further comprises
receiving a D2D bandwidth allocation request from at least one UE
in the D2D cluster, scheduling bandwidth for the at least one UE,
and transmitting a D2D bandwidth allocation message to the at least
one UE within the D2D cluster to enable the at least one UE to
determine when bandwidth is allocated for the at least one UE to
communicate with another UE in the D2D cluster.
[0068] FIG. 14 provides an example illustration of the wireless
device, such as a user equipment (UE), a mobile station (MS), a
mobile wireless device, a mobile communication device, a tablet, a
handset, or other type of wireless device. The wireless device can
include one or more antennas configured to communicate with a node
or transmission station, such as a base station (BS), an evolved
Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a
remote radio equipment (RRE), a relay station (RS), a radio
equipment (RE), a remote radio unit (RRU), a central processing
module (CPM), or other type of wireless wide area network (WWAN)
access point. The wireless device can be configured to communicate
using at least one wireless communication standard including 3GPP
LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and Wi-Fi.
The wireless device can communicate using separate antennas for
each wireless communication standard or shared antennas for
multiple wireless communication standards. The wireless device can
communicate in a wireless local area network (WLAN), a wireless
personal area network (WPAN), and/or a WWAN.
[0069] FIG. 14 also provides an illustration of a microphone and
one or more speakers that can be used for audio input and output
from the wireless device. The display screen can be a liquid
crystal display (LCD) screen, or other type of display screen such
as an organic light emitting diode (OLED) display. The display
screen can be configured as a touch screen. The touch screen can
use capacitive, resistive, or another type of touch screen
technology. An application processor and a graphics processor can
be coupled to internal memory to provide processing and display
capabilities. A non-volatile memory port can also be used to
provide data input/output options to a user. The non-volatile
memory port can also be used to expand the memory capabilities of
the wireless device. A keyboard can be integrated with the wireless
device or wirelessly connected to the wireless device to provide
additional user input. A virtual keyboard can also be provided
using the touch screen.
[0070] Various techniques, or certain aspects or portions thereof,
can take the form of program code (i.e., instructions) embodied in
tangible media, such as floppy diskettes, CD-ROMs, hard drives,
non-transitory computer readable storage medium, or any other
machine-readable storage medium wherein, when the program code is
loaded into and executed by a machine, such as a computer, the
machine becomes an apparatus for practicing the various techniques.
In the case of program code execution on programmable computers,
the computing device can include a processor, a storage medium
readable by the processor (including volatile and non-volatile
memory and/or storage elements), at least one input device, and at
least one output device. The volatile and non-volatile memory
and/or storage elements can be a RAM, EPROM, flash drive, optical
drive, magnetic hard drive, or other medium for storing electronic
data. The base station and mobile station can also include a
transceiver module, a counter module, a processing module, and/or a
clock module or timer module. One or more programs that can
implement or utilize the various techniques described herein can
use an application programming interface (API), reusable controls,
and the like. Such programs can be implemented in a high level
procedural or object oriented programming language to communicate
with a computer system. However, the program(s) can be implemented
in assembly or machine language, if desired. In any case, the
language can be a compiled or interpreted language, and combined
with hardware implementations.
[0071] It should be understood that many of the functional units
described in this specification have been labeled as modules, in
order to more particularly emphasize their implementation
independence. For example, a module can be implemented as a
hardware circuit comprising custom VLSI circuits or gate arrays,
off-the-shelf semiconductors such as logic chips, transistors, or
other discrete components. A module can also be implemented in
programmable hardware devices such as field programmable gate
arrays, programmable array logic, programmable logic devices or the
like.
[0072] Modules can also be implemented in software for execution by
various types of processors. An identified module of executable
code can, for instance, comprise one or more physical or logical
blocks of computer instructions, which can, for instance, be
organized as an object, procedure, or function. Nevertheless, the
executables of an identified module need not be physically located
together, but can comprise disparate instructions stored in
different locations which, when joined logically together, comprise
the module and achieve the stated purpose for the module.
[0073] Indeed, a module of executable code can be a single
instruction, or many instructions, and can even be distributed over
several different code segments, among different programs, and
across several memory devices. Similarly, operational data can be
identified and illustrated herein within modules, and can be
embodied in any suitable form and organized within any suitable
type of data structure. The operational data can be collected as a
single data set, or can be distributed over different locations
including over different storage devices, and can exist, at least
partially, merely as electronic signals on a system or network. The
modules can be passive or active, including agents operable to
perform desired functions.
[0074] Reference throughout this specification to "an example"
means that a particular feature, structure, or characteristic
described in connection with the example is included in at least
one embodiment of the present invention. Thus, appearances of the
phrases "in an example" in various places throughout this
specification are not necessarily all referring to the same
embodiment.
[0075] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials can be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the contrary.
In addition, various embodiments and example of the present
invention can be referred to herein along with alternatives for the
various components thereof. It is understood that such embodiments,
examples, and alternatives are not to be construed as defacto
equivalents of one another, but are to be considered as separate
and autonomous representations of the present invention.
[0076] Furthermore, the described features, structures, or
characteristics can be combined in any suitable manner in one or
more embodiments. In the following description, numerous specific
details are provided, such as examples of layouts, distances,
network examples, etc., to provide a thorough understanding of
embodiments of the invention. One skilled in the relevant art will
recognize, however, that the invention can be practiced without one
or more of the specific details, or with other methods, components,
layouts, etc. In other instances, well-known structures, materials,
or operations are not shown or described in detail to avoid
obscuring aspects of the invention.
[0077] While the forgoing examples are illustrative of the
principles of the present invention in one or more particular
applications, it will be apparent to those of ordinary skill in the
art that numerous modifications in form, usage and details of
implementation can be made without the exercise of inventive
faculty, and without departing from the principles and concepts of
the invention. Accordingly, it is not intended that the invention
be limited, except as by the claims set forth below.
* * * * *