The present disclosure relates generally to a system and method for digital communications, and more particularly to a system and method for operations enabling direct mobile communications in a wireless communication system.
In the field of wireless communication, there has been increasing demand for direct device-to-device communication (D2D), direct mobile communication (DMC), and the like. This form of communication refers to a communication mode between two or more user equipments (UEs) that does not include or does not always include a communications controller in a communication path between or among the UEs. DMC will be used herein to denote this form of communication. Generally, DMC communications involve direct communications between multiple DMC devices (the DMC devices are commonly referred to as a UE, a mobile station, a communications device, a subscriber, a terminal, and the like). DMC communications occur as point-to-point (PTP) communications, either point-to-single-point or point-to-multipoint, without having the communications passing through and being fully controlled by a communications controller, such as an evolved NodeB (eNB), a NodeB, a base station, a controller, a communications controller, and the like.
A DMC link is different than a cellular link. A cellular link between UEs involves the data shared between the UEs transiting through a network infrastructure node such as an eNB, relay node, or the like. Note, however, that for a DMC link, while data is directly exchanged between the UEs, the control information for the DMC link may still transit through a network node. DMC can enable a cellular network to offload a portion of its base station traffic. In addition to offloading base-station traffic, DMC also enables proximity-based advertisement for local business entities, which can be a revenue source for such entities. DMC can also enable an end user of a user equipment to find and identify nearby friends. Ad hoc-type services can also be provided among user equipments that are physically near each other. DMC is also a key enabler of local social networking.
There are two main ways of implementing DMC communication, namely a device-centric arrangement and a network-centric arrangement. In the device-centric arrangement, DMC communication takes place without network oversight. However, in the network-centric arrangement the network initiates DMC communication between UEs when conditions (e.g., the proximity of UEs, overall traffic demand, the location of non-DMC UEs, etc.) are appropriate and supports the DMC communication by, for example, transmitting control information, allocating resources, and the like. The network-centric arrangement offers potential for offloading local traffic from the network, which is attractive to cellular operators. Note that while fully device-centric and fully network-centric can be used, in practice, the solution chosen for a DMC deployment may simultaneously use features of both approaches.
Embodiments of the present disclosure provide methods of dynamically allocating resources for DMC communication.
In accordance with an example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes informing the UEs in the DMC group of a set of UEs outside the DMC group and assigning transmission resources for the set of UEs outside the DMC group. The method also includes assigning potential transmission resources for the DMC group and transmitting a resource allocation to the set of UEs outside the DMC group. The resource allocation indicates that the transmission resources and the potential transmission resources are the same.
In accordance with another example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes receiving from a base station an identification of a set of UEs outside the DMC group and receiving an allocation of transmission resources for the set of UEs outside the DMC group. The method also includes using the allocation of transmission resources for communication with other UEs in the DMC group.
In accordance with another example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes assigning, for the UEs in the DMC group, identifications for transmission. The method also includes informing the UEs in the DMC group of the identifications and transmitting to the UEs in the DMC group an assignment identified by the identifications assigned. The assignment includes a downlink control indicator (DCI) and the identifications informing UEs in the DMC group of a transmitting UE and a receiving UE.
In accordance with another example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes receiving from a base station identities of UEs in the DMC group. The method also includes receiving an assignment based on the identities of UEs in the DMC group and preparing to transmit or receive based on the assignment. The assignment includes a downlink control indicator (DCI).
In accordance with another example embodiment, an apparatus for allocating resources to user equipments (UEs) in a Direct Mobile Communications (DMC) group. The apparatus includes a transmitter, a receiver, and a processor operably coupled to the transmitter and to the receiver. The processor is configured to identify, for the UEs in the DMC group, an allocation of resources accounting for a UE outside the DMC group and to inform the UEs in the DMC group which of the resources may be used by the UEs in the DMC group to engage in DMC communication.
In accordance with another example embodiment, an apparatus for dynamically allocating resources to user equipments (UEs) in a Direct Mobile Communications (DMC) group. The apparatus includes a transmitter, a receiver, and a processor operably coupled to the transmitter and to the receiver. The processor is configured to receive an identification of an allocation of resources accounting for a UE outside the DMC group and to initiate DMC communication based on the allocation of resources.
In accordance with another example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communications (DMC) group. The method includes establishing a common group identification for the UEs in the DMC group and assigning a sub-identification unique to each of the UEs in the DMC group. The method also includes placing the sub-identification of one of the UEs in a field of downlink control information (DCI) to indicate that the one of the UEs is authorized to transmit and generating a cyclical redundancy check (CRC) using the DCI and masking the CRC with the common group identification. The method further includes transmitting the DCI and the masked CRC in a channel assignment that, when received and de-masked by each of the UEs in the DMC group, permits the UEs in the DMC group to determine if they have been allocated resources and, if so, identifies that the one of the UEs is authorized to transmit based on the sub-identification placed in the field of the DCI.
In accordance with another example embodiment, a method of dynamically allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes receiving a common group identification identifying the UEs in the DMC group and receiving a sub-identification uniquely identifying each of the UEs in the DMC group. The method also includes receiving a channel assignment including downlink control information (DCI) and a masked cyclical redundancy check (CRC) and de-masking the masked CRC using the common group identification to generate a received CRC. The method further includes generating a new CRC using the DCI and comparing the received CRC with the new CRC and, if there is a match, receiving an allocation of resources and an identification of which of the UEs in the DMC group is authorized to transmit based on the sub-identification in the field of the DCI.
In accordance with another example embodiment, a method of allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes establishing a group identification for each of the UEs in the DMC group. The group identification includes a first portion common to the DMC group and a second portion unique to each of the UEs in the DMC group. The method also includes identifying one of the UEs as authorized to transmit and generating a cyclical redundancy check (CRC) using downlink control information (DCI) and masking the CRC with the group identification for each of the UEs in the DMC group. The method further includes transmitting the DCI and the masked CRCs in channel assignments that, when received and de-masked by each of the UEs in the DMC group, permit the UEs to determine if they have been allocated resources and, if so, to identify the one of the UEs authorized to transmit based on the second portion of the group identification.
In accordance with another example embodiment, a method of dynamically allocating resources to user equipments (UEs) in a Direct Mobile Communication (DMC) group. The method includes receiving a group identification. The group identification includes a first portion common to the DMC group and a second portion unique to each of the UEs in the DMC group. One of the second portions identifies one of the UEs as authorized to transmit. The method also includes receiving channel assignments including downlink control information (DCI) and masked cyclical redundancy checks (CRCs) and de-masking the masked CRCs using the group identification to generate received CRCs. The method further includes generating a new CRC using the DCI and comparing the received CRCs with the new CRC and, if there is a match, receiving an allocation of resources and an identification of which of the UEs in the DMC group is authorized to transmit based on the second portion of the group identification.
For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative and do not limit the scope of the present disclosure.
As will be more fully explained below, several processes to dynamically allocate resources, both in time and frequency, to a group of user equipments (UEs) engaging in direct-mobile-communication (DMC) are introduced herein.
Referring now to
While only a pair of DMC UEs 12, 14, which may be collectively referred to herein as the DMC group, are illustrated in
In addition to the above, while a single cellular UE 16 is illustrated in
In order to keep UE complexity low, a half frequency-division-duplex (“FDD”) communication protocol for the DMC link is assumed, such as in the uplink band of a Third Generation Partnership Program (“3GPP”) Long Term Evolution (“LTE”) system. Although FDD protocol is described, time-division-duplex (“TDD”) communication protocol can also be used for DMC. Although described with DMC using uplink spectrum, the concepts disclosed herein may also be deployed using downlink spectrum. Use of the uplink band implies that when one DMC UE is transmitting, the other DMC UEs should be prepared to receive. For the purpose of correctly transmitting and receiving a packet, the UEs involved in a DMC group (single-link or multiple-link) are informed when (e.g., the time resources), where (e.g., the frequency resources), and how (e.g., the related Hybrid Automatic Repeat reQuest (HARQ) procedure, modulation and coding scheme (“MCS”), power, and multi-input/multi-output (“MIMO”) scheme) to transmit and receive. To address, for example, the “when” and “where” aspects of DMC communication, resources may be dynamically allocated as described herein.
Referring now to
In some embodiments, the base station 10 periodically or repeatedly identifies the UEs outside the DMC group (e.g., UE 16) that will not experience interference when the DMC UEs 12, 14 engage in DMC communication. This identification may be at least partly based on signal strength measurements. While described with the level of interference experienced by UEs outside of the group, the base station may identify the target UEs based on other criteria, such as traffic demand, location, and so forth. As such, a list of cellular UEs received or solicited by the DMC UEs 12, 14 is updated from time to time and is not static.
Still referring to
In block 34, the DMC UEs 12, 14 are permitted to engage in DMC communication using the resources of the cellular UE 16, which the base station 10 identified as a UE that would not experience interference when the DMC UEs 12, 14 engage in DMC communication. In some embodiments, the base station 10 authorizes one of the DMC UEs 12, 14 to transmit using techniques such as having the DMC UEs take turns, using a predetermined order, or using techniques described in a reference of time domain allocation. In an embodiment, each UE in the DMC group may be linked to a different set of cellular UEs for the authorization of transmission. So, when a UE monitors the channel assignments for the UEs in its corresponding set, it will transmit as instructed. The UEs in the DMC group should be informed of the sets of cellular UEs of each other. Therefore, the other DMC UEs in the group expect to receive from the DMC UE authorized to transmit.
In some embodiments, the base station 10 transmits a common group identification to identify members of the DMC group and a sub-group identification to authorize one of the UEs in the DMC group to transmit. This way, a DMC UE is uniquely identified by its group ID and sub-group ID. The base station may allocate resources to a group of DMC UEs, and the resource allocation within the group UE may be done using the techniques described in a time resource allocation reference.
Referring now to
In block 42, the DMC UEs 12, 14 engage in DMC communication using the resources of the cellular UE 16, which the base station 10 identified as a UE that would not experience interference when the DMC UEs engage in DMC communication.
Referring now to
In block 46, the cellular UE 16, which is outside the DMC group and will not experience interference when the user equipments in the DMC group engage in DMC communication, is identified for the DMC UEs 12, 14. In block 48, the base station 10 transmits channel assignments that, among other things, allocate resources to the cellular UE 16.
In block 50, the DMC UEs 12, 14 are permitted to engage in DMC communication using resources other than the resources allocated to the cellular UE 16, which the base station 10 identified as a UE that would experience interference when the DMC UEs 12, 14 engage in DMC communication.
Referring now to
In block 58, the DMC UEs 12, 14 engage in DMC communication using resources other than the resources allocated to the cellular UE 16, which the base station 10 identified as a UE that would experience interference when the DMC UEs 12, 14 engage in DMC communication.
For an LTE embodiment, the DMC UEs would need to monitor the ePDCCH or PDCCH to obtain the resource assignments for the corresponding cellular UEs. If they have to monitor PDCCH, the number of blind decodings would be significantly increased since the DMC UEs would need to monitor the entire search spaces of each of the cellular UEs it has to monitor. With an ePDCCH, such a problem may not exist if the UEs to monitor are assigned the same search space. In that case, by monitoring a single search space (the one common to all UEs it has to monitor), the DMC UE will get all the resource assignments.
Referring collectively to
In block 78 of
In block 84 of
As will be more fully explained below, when received and de-masked by each of the UEs 66, 68, 70 in the DMC group 72, the DCI informs the UEs of the resources allocation, and perhaps the modulation coding scheme (MCS) if the system is configured so that the MCS determination is done by the eNB, and so on. If the CRC is correctly checked by de-masking the DMC group ID, then the UEs in the DMC group know the channel assignment is for the group; the DCI identifies UE 1 as the user equipment authorized to transmit based on the sub-identification placed in the field 80 of the DCI 82, and in the meantime, the other UEs in the DMC group are also implicitly informed to be ready to receive.
Referring collectively to
In block 100 of
Referring collectively to
As shown in
In block 128 of
As will be more fully explained below, when received and de-masked by each of the UEs 118, 122 in the DMC group, the DCI 82 informs the UEs 118, 122 of the resource allocation. The identification 116 or identification 120 masked on the CRC will inform the UEs 118, 122 who is permitted to transmit and who should expect to receive. For example, if identification 120 is detected, then the second portion 126 of the identification 120 is a “1.” In this example, UE 122 is supposed to transmit because its identification is masked to the CRC and UE 118 is destined to receive because there is a “0” included in the second portion 126 of its identification 116.
Referring collectively to
In block 144 of
Next, in block 152 of
The retransmissions can be indicated in the DCI 132 also by a New Data Indicator bit.
Referring now to
Referring now to
Although embodiments described hereinabove operate within the specifications of a cellular communication network such as a 3GPP-LTE cellular network, other wireless communication arrangements are contemplated within the broad scope of an embodiment, including WiMAX, GSM, Wi-Fi, and other wireless communication systems.
It is noted that, unless indicated otherwise, functions described herein can be performed in either hardware or software, or some combination thereof, with or without human intervention. In an embodiment, the functions are performed by a processor such as a computer or an electronic data processor in accordance with code such as computer program code, software, and/or integrated circuits that are coded to perform such functions, unless indicated otherwise.
While the disclosure has been made with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.