CN113613180B - LTE-U system component carrier selection method facing throughput demand - Google Patents

LTE-U system component carrier selection method facing throughput demand Download PDF

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CN113613180B
CN113613180B CN202110894202.5A CN202110894202A CN113613180B CN 113613180 B CN113613180 B CN 113613180B CN 202110894202 A CN202110894202 A CN 202110894202A CN 113613180 B CN113613180 B CN 113613180B
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users
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CN113613180A (en
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郑军
唐佳欣
肖杰
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Southeast University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
    • H04W4/08—User group management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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Abstract

The invention discloses a method for selecting LTE-U system component carriers facing throughput requirements, which comprises the following steps: (1) initializing the number of coexisting network users at the beginning of the next CSAT period when the CSAT period begins; (2) updating user information on each carrier according to the dynamic arrival or departure of users in the coexisting network in a CSAT period; (3) and before the CSAT period is finished, selecting a proper carrier for the LTE-U new user arriving in the period. According to the invention, on the basis of ensuring the coexistence fairness of the LTE-U and the WiFi and the throughput requirement of the existing LTE-U user in the network, one or more proper carrier waves are selected for the LTE-U new user according to the throughput requirement of the LTE-U new user, so that the LTE-U user satisfaction degree of the coexistence network is effectively improved.

Description

LTE-U system component carrier selection method facing throughput demand
Technical Field
The invention relates to the technical field of coexistence of unlicensed frequency bands of an LTE-U system and a WiFi system in mobile communication, in particular to a method for selecting component carriers of the LTE-U system facing throughput requirements.
Background
With the diversification of cellular network services, LTE-U systems need to have the capability to support different services and user specific throughput requirements. For example, some IOT devices require low power transmission to extend battery life, while throughput requirements are low, while services such as AR/VR and high definition live online have high throughput requirements. Due to the diversification of 5G application scenes, in consideration of the difference of user throughput demands in actual scenes and the instability of channel quality on an unlicensed frequency band, the LTE-U base station is not limited to scheduling time-frequency resources in a single frequency band, but uses a Carrier Aggregation (CA) technology to enable a user to simultaneously use a plurality of orthogonal component carriers of the unlicensed frequency band so as to meet the specific demands of the user on the throughput. The carrier aggregation technology proposed by 3GPP in R10, which obtains a larger bandwidth by aggregating multiple continuous or discontinuous component carriers, and provides a higher data rate for users to meet the requirements of high throughput services for users.
An effective component carrier selection method is needed to realize carrier aggregation, and a proper carrier (single or multiple carriers) is selected and allocated to a user so as to meet the throughput requirement of the user. When selecting the carrier, the throughput requirement information of the user, the carrier aggregation capability of the terminal, and the state information of the channel, such as the load condition on each component carrier, the channel quality, etc., need to be considered comprehensively. The component carrier selection methods of the conventional LTE/LTE-a system are mainly classified into two categories: one based on load balancing and the other based on channel quality. The problem of selecting the carrier wave in the unlicensed frequency band is different from that of the conventional LTE system because factors such as load balancing and channel quality need to be considered, as well as coexistence fairness between the LTE-U system and the WiFi system, randomness of WiFi user arrival, and the like. Therefore, the component carrier selection method adopted in the LTE/LTE-a system cannot be directly applied to the LTE-U system, and research and design of an effective component carrier selection method suitable for the LTE-U and WiFi coexisting network are required.
Disclosure of Invention
The invention aims to provide a Component Carrier Selection (CCS) method of an LTE-U system facing to throughput requirements for solving the problems. According to the method, on the basis of ensuring the coexistence fairness of the LTE-U and the WiFi and the throughput requirement of the existing LTE-U users in the network, one or more proper carrier waves are selected for the LTE-U new users according to the throughput requirement of the LTE-U new users, and the LTE-U user satisfaction degree of the coexistence network is effectively improved.
In order to achieve the aim, the method adopted by the invention is an LTE-U system component carrier selection method facing the throughput requirement, and the method mainly comprises the following steps:
(1) initializing the number of coexisting network users at the beginning of the next CSAT period: suppose the number of WiFi users and LTE-U users needing service on the ith carrier wave in the coexisting network at the beginning of the tth CSAT period is respectively
Figure BDA0003197189920000021
And
Figure BDA0003197189920000022
since WiFi users and LTE-U users can dynamically arrive or leave in the coexisting network in the period, the number of users on the ith carrier wave at the beginning of the t +1 CSAT period
Figure BDA0003197189920000023
And
Figure BDA0003197189920000024
there will be a corresponding increase or decrease, respectively. To determine
Figure BDA0003197189920000025
And
Figure BDA0003197189920000026
firstly, set up
Figure BDA0003197189920000027
Then, as the user arrives or departs, the
Figure BDA0003197189920000028
And
Figure BDA0003197189920000029
increase and decrease are carried out;
(2) in the t CSAT period, according to the dynamic arrival or departure of users in the coexisting network, the number of users needing service on each carrier wave is updated: if one user (WiFi user or LTE-U user) leaves the coexisting network after finishing transmission, the user is moved out of the corresponding user group on the carrier wave used by the user, and the user is synchronized with the coexisting network
Figure BDA00031971899200000210
Or
Figure BDA00031971899200000211
Performing a subtraction operation; if a new user arrives at the coexisting network, firstly, the type of the new user is judged, if the user is a WiFi user, the user is added into the ith carrier wave used by the associated AP of the userAnd to WiFi user group on
Figure BDA00031971899200000212
Performing an adding operation; if the user is an LTE-U user, the carrier is not immediately selected and distributed for the user, but the new user is recorded first, and the carrier selection is carried out for the user before the current period is finished;
(3) before the end of the tth CSAT period, selecting proper carriers for all new LTE-U users arriving in the period: and according to the arrival time sequence of the LTE-U new users, sequentially selecting proper carriers for all the LTE-U new users arriving in the period.
In the method, in the steps (1) - (3), a network architecture integrating the LTE-U system and the WiFi system based on a network virtualization technology is adopted to share information between the LTE-U system and the WiFi system. The converged network architecture is described as follows:
one LTE-U subsystem and a plurality of WiFi subsystems coexist in an unauthorized frequency band; in the coexisting network, an LTE-U subsystem consists of a base station BS and a plurality of uniformly distributed user UEs, and each LTE-U user has a specific throughput requirement; each WiFi subsystem consists of an AP and a plurality of user STAs which are uniformly distributed; assume that the unlicensed band has N orthogonal component carriers, denoted CC1,CC2,…,CCN(ii) a Each CC may be shared by LTE-U systems and one WiFi system; each WiFi AP uses one carrier, so that in order to avoid serious co-channel interference caused by adjacent geographic positions, different WiFi APs are further assumed to use different carriers, and thus mutual interference among different WiFi APs can be ignored; the LTE-U BS can use all N carriers to provide service for the LTE-U user; downlink transmission of the LTE-U system adopts an OFDMA channel access mechanism of base station centralized scheduling to distribute time-frequency resources for users; the WiFi system adopts a CSMA/CA channel access mechanism based on the competition of 802.11n, and users access the channel in a competition mode; and an F-CSAT mechanism based on time division multiplexing is adopted on each carrier to coordinate coexistence of the two systems.
The method adopts a Network architecture of fusing an LTE-U system and a WiFi system based on a Network virtualization technology, respectively virtualizes physical entities LTE-U BS and WiFi AP in the LTE-U system and the WiFi system into corresponding virtualized Network entities vBS (virtual BS) and vAP (virtual AP), and manages the virtual entities through a Software Defined Network (SDN) technology. The LTE-U BS virtual entity (vBS) and the WiFi AP virtual entity (vAP) are uniformly controlled by one SDN controller, and information such as load intensity, user throughput demand and channel state of a wireless access network side is received from the LTE-U BS and the WiFi AP physical entity. The LTE-U BS can use N carriers to provide service for LTE-U users, and the LTE-U users have specific throughput requirements. The virtual entities intercommunicate the received information, and accordingly, a proper carrier is selected for the LTE-U user so as to meet the throughput requirement of the LTE-U user.
In the method of the present invention, in step (2), the user information on the carrier is updated according to the dynamic arrival or departure of the user in the current CSAT period, and the specific process is as follows:
when the t CSAT period begins, the number of WiFi users and LTE-U users needing service on the ith carrier wave in the coexisting network is respectively
Figure BDA0003197189920000031
And
Figure BDA0003197189920000032
firstly, setting:
Figure BDA0003197189920000033
in the t CSAT period, when a user leaves the coexisting network after finishing transmission, if the user is a WiFi user, the user is moved out of the used CCiWiFi user group on, namely:
Figure BDA0003197189920000034
no longer occupying CC in t +1 CSAT periodi(ii) a If the user is an LTE-U user, each CC in the carrier wave set used by the useriMove the user out of CCiLTE-U user group above, namely:
Figure BDA0003197189920000035
Figure BDA0003197189920000036
the carriers in the set are no longer occupied for the t +1 CSAT period.
In the t CSAT period, when a new user arrives at the coexisting network, if the user is a WiFi user, the AP associated with the user is firstly obtained, and then the user is added into the CC used by the associated APiWiFi user group on, namely:
Figure BDA0003197189920000037
contention for access to the channel starts from the t +1 th period. If the user is an LTE-U user, the carrier is not immediately selected and allocated, and the carrier selection is performed until the period is finished.
In the method of the present invention, in step (3), before the end of the current CSAT period, a suitable carrier is selected for all new LTE-U users that arrive in the period, and the specific process is as follows:
before the t CSAT period ends, the number of WiFi users and LTE-U users on the ith carrier wave changes relative to the beginning of the period, and at this time, the number of WiFi users needing service on the ith carrier wave at the beginning of the t +1 CSAT period can be considered to be the number of users
Figure BDA0003197189920000041
The number of LTE-U users needing service on the ith carrier wave is determined
Figure BDA0003197189920000042
It is determined according to the result of carrier selection. And when the carrier selection is carried out, according to the arrival time sequence of the LTE-U new users, selecting and allocating proper carriers for all the LTE-U new users arriving in the period in sequence.
Suppose that when carrier selection is performed for a new LTE-U arriving user, the ith carrier is allocated
Figure BDA0003197189920000043
The throughput requirement of the kth LTE-U user on the ith carrier is
Figure BDA0003197189920000044
Then the total throughput requirement of the LTE-U user on the ith carrier is:
Figure BDA0003197189920000045
assume that the throughput requirement of the new LTE-U user is
Figure BDA0003197189920000046
Then whatever carrier(s) is/are selected for the user, the selected carrier(s) should meet its throughput requirements, while the total throughput requirements of the LTE-U users already allocated on the selected carrier(s) must be guaranteed. If a new LTE-U user is allocated to the ith component carrier, the maximum throughput that the carrier can currently provide for the new user is:
Figure BDA0003197189920000047
where r (n) represents the system throughput that can be achieved when the ith carrier is occupied solely by the WiFi system with n users,
Figure BDA0003197189920000048
indicating the system throughput that can be achieved when the LTE-U system alone occupies the ith component carrier,
Figure BDA0003197189920000049
temporary values representing the LTE-U OFF duty cycle on the ith carrier when carrier selection is performed for a new LTE-U user. Since the user allocation and the LTE-U OFF duty cycle on each carrier in the t +1 th cycle can only be determined after all LTE-U users complete carrier selection, this temporary value is only related to the currently completed carrier selection result. Under the condition that the number of WiFi users is determined, if other LTE-U users exist laterAnd when the ith carrier is selected, the LTE-U ON duty ratio is increased along with the increase of the LTE-U users, so that the throughput requirement of the LTE-U users which finish the carrier selection can be ensured, namely the carrier selection of the following users cannot influence the result of the carrier selection of the previous user.
Under the assumption and analysis conditions, the component carrier selection problem considered by the present invention is to select a group of component carriers I with the minimum number for each LTE-U user arriving in the t-th CSAT period to meet the throughput requirement of the user, under the condition of ensuring coexistence fairness of the LTE-U system and the WiFi system and the throughput requirement of the existing LTE-U user in the network, that is:
optimizing the target:
Figure BDA0003197189920000051
constraint conditions are as follows:
Figure BDA0003197189920000052
wherein I represents a group of component carriers selected by a new LTE-U user, C represents the number of carriers selected by the new LTE-U user, and M represents the upper limit of the carrier selection number (C is less than or equal to M); equation (4) indicates that any C-1 carriers cannot meet the throughput requirement of the new user and that there are C carriers that can meet the throughput requirement of the new user. If any M carriers cannot meet the throughput requirement of the new user, the user is refused to access the network.
When selecting a carrier for an LTE-U new user, it is first determined whether a single carrier exists that can meet the throughput requirement of the new user. If the carrier I exists, selecting the carrier i capable of providing the maximum throughput for the LTE-U new user from all single carriers capable of meeting the requirement*(ii) a If any single carrier can not meet the throughput requirement of the new user, sequentially increasing the number C of carrier selections until any C-1 carriers can not meet the throughput requirement of the new user and C carriers can meet the throughput requirement of the new user. If a plurality of groups of C carriers can meet the requirement, selecting a group of C carriers I which can provide the maximum total throughput for a new LTE-U user*(ii) a If renAnd if the M carriers cannot meet the throughput requirement of the new user, rejecting the user to access the LTE-U system. The main steps of LTE-U new user carrier selection are as follows:
a) when a carrier is selected for a new LTE-U user, the throughput requirement of the user is acquired firstly
Figure BDA0003197189920000053
b) Calculate each CCiMaximum throughput currently available for new users
Figure BDA0003197189920000054
c) All N carriers are divided into
Figure BDA0003197189920000055
In descending order, i.e.
Figure BDA0003197189920000056
d) The initial value of the carrier selection number C is set to 1. If the first C carriers can meet the throughput requirement of the user, that is
Figure BDA0003197189920000057
The user completes carrier selection; otherwise, sequentially increasing the number C of carrier selections until the first C carriers can meet the throughput requirement of the user. And if the first M carriers cannot meet the throughput requirement of the new user, rejecting the user to access the LTE-U system.
Advantageous effects
Compared with the prior art, the invention has the following advantages:
1) in consideration of the difference of user throughput requirements in an actual scene and the instability of channel quality on an unauthorized frequency band, the LTE-U base station is not limited to scheduling time-frequency resources in a single frequency band, but uses a Carrier Aggregation (CA) technology to enable a user to simultaneously use a plurality of orthogonal component carriers of the unauthorized frequency band so as to meet the specific requirements of the user on the throughput and meet the requirements in actual engineering application.
2) The LTE-U system component carrier selection method facing the throughput demand provided by the invention can select one or more proper carriers for the LTE-U new user according to the throughput demand of the LTE-U new user under the condition of ensuring the coexistence fairness of the LTE-U and the WiFi and the throughput demand of the existing LTE-U user in the network, thereby effectively improving the satisfaction degree of the LTE-U user in the coexistence network.
Drawings
FIG. 1 is a flow chart of a method for selecting LTE-U system component carriers for meeting throughput requirements
FIG. 2-LTE-U and WiFi coexistence network scenario diagram based on converged network architecture
FIG. 3 is a schematic diagram of a carrier selection procedure for LTE-U
Detailed Description
The present invention will be further described with reference to the accompanying drawings. The invention provides a method for selecting LTE-U system component carrier waves facing to throughput requirements, which is implemented according to the following steps as shown in figure 1:
(1) initializing the coexisting network user information at the beginning of the next CSAT period: suppose the number of WiFi users and LTE-U users needing service on the ith carrier wave in the coexisting network at the beginning of the tth CSAT period is respectively
Figure BDA0003197189920000061
And
Figure BDA0003197189920000062
since WiFi users and LTE-U users can dynamically arrive or leave in the coexisting network in the period, the number of users on the ith carrier wave at the beginning of the t +1 CSAT period
Figure BDA0003197189920000063
And
Figure BDA0003197189920000064
there will be a corresponding increase or decrease, respectively. To determine
Figure BDA0003197189920000065
And
Figure BDA0003197189920000066
firstly, setting:
Figure BDA0003197189920000067
then, as the user arrives or departs, the
Figure BDA0003197189920000068
And
Figure BDA0003197189920000069
increase or decrease is performed.
The method of the present invention is directed to an unlicensed frequency band coexistence network composed of a single LTE-U subsystem and a plurality of WiFi subsystems, as shown in fig. 2. In the coexisting network, an LTE-U subsystem consists of a base station BS and a plurality of uniformly distributed user UEs, and each LTE-U user has a specific throughput requirement. Each WiFi subsystem consists of one AP and several evenly distributed user STAs. The unlicensed frequency band is assumed to have N orthogonal Component Carriers (CCs), which are denoted as CC1,CC2,…,CCN. Each CC may be shared by the LTE-U system and one WiFi system. One carrier is used per WiFi AP. In order to avoid severe co-channel interference due to geographical proximity, it is further assumed that different WiFi APs use different carriers, so that mutual interference between different WiFi APs can be ignored. The LTE-U BS may use all N carriers to serve LTE-U users. Downlink transmission of the LTE-U system adopts an OFDMA channel access mechanism of base station centralized scheduling to distribute time-frequency resources for users; the WiFi system adopts an 802.11n CSMA/CA channel access mechanism based on competition, and users access the channel in a competition mode. And an F-CSAT mechanism based on time division multiplexing is adopted on each carrier wave to coordinate the coexistence of the two systems.
The method adopts a Network architecture of fusing an LTE-U system and a WiFi system based on a Network virtualization technology, virtualizes physical entities in the LTE-U system and the WiFi system, namely an LTE-U BS and a WiFi AP, into a corresponding virtualized Network entity vBS (virtual BS) and a virtual AP (virtual AP), and manages the virtual entities through a Software Defined Network (SDN) technology. The LTE-U BS virtual entity (vBS) and the WiFi AP virtual entity (vAP) are uniformly controlled by one SDN controller, and information such as load intensity, user throughput demand and channel state of a wireless access network side is received from the LTE-U BS and the WiFi AP physical entity. The LTE-U BS can use N carriers to provide service for LTE-U users, and the LTE-U users have specific throughput requirements. The virtual entities intercommunicate the received information, and accordingly, a proper carrier is selected for the LTE-U user so as to meet the throughput requirement of the LTE-U user.
(2) In the t CSAT period, according to the dynamic arrival or departure of users in the coexisting network, updating the user information on the carrier:
when the t CSAT period begins, the number of WiFi users and LTE-U users needing service on the ith carrier wave in the coexisting network is respectively
Figure BDA0003197189920000071
And
Figure BDA0003197189920000072
firstly, setting:
Figure BDA0003197189920000073
in the t CSAT period, when a user leaves the coexisting network after finishing transmission, if the user is a WiFi user, the user is moved out of the used CCiWiFi user group on, namely:
Figure BDA0003197189920000074
no longer occupying CC in t +1 CSAT periodi(ii) a If the user is an LTE-U user, each CC in the carrier wave set used by the useriMove the user out of CCiLTE-U user group above, namely:
Figure BDA0003197189920000075
Figure BDA0003197189920000076
the carriers in the set are no longer occupied for the t +1 CSAT period.
In the t CSAT period, when a new user arrives at the coexisting network, if the user is a WiFi user, the AP associated with the user is firstly obtained, and then the user is added into the CC used by the associated APiWiFi user group on, namely:
Figure BDA0003197189920000077
contention for access to the channel starts from the t +1 th period. If the user is an LTE-U user, the carrier is not immediately selected and allocated for the user, and the carrier selection is carried out before the period is ended.
(3) Before the end of the tth CSAT period, selecting proper carriers for all LTE-U new users arriving in the period:
before the t CSAT period ends, the number of WiFi users and LTE-U users on the ith carrier wave changes relative to the beginning of the period, and at this time, the number of WiFi users needing service on the ith carrier wave at the beginning of the t +1 CSAT period can be considered to be the number of users
Figure BDA0003197189920000081
The number of LTE-U users needing service on the ith carrier wave is determined
Figure BDA0003197189920000082
It is determined according to the result of carrier selection. When carrier selection is carried out, all the n arriving in the period are sequentially carried out according to the time sequence of the arrival of the LTE-U new userLAnd (t) selecting and allocating proper carriers for the LTE-U new users.
Suppose that when carrier selection is performed for a new LTE-U arriving user, the ith carrier is allocated
Figure BDA0003197189920000083
The throughput requirement of the kth LTE-U user on the ith carrier is
Figure BDA0003197189920000084
Then the total throughput requirement of the LTE-U user on the ith carrier is:
Figure BDA0003197189920000085
assume that the throughput requirement of the new LTE-U user is
Figure BDA0003197189920000086
Then whatever carrier(s) is/are selected for the user, the selected carrier(s) should meet its throughput requirements, while the total throughput requirements of the LTE-U users already allocated on the selected carrier(s) must be guaranteed. If a new LTE-U user is allocated to the ith component carrier, the maximum throughput that the carrier can currently provide for the new user is:
Figure BDA0003197189920000087
where r (n) represents the system throughput that can be achieved when a WiFi system with n users occupies the ith carrier by itself,
Figure BDA0003197189920000088
indicating the system throughput that can be achieved when the LTE-U system alone occupies the ith component carrier,
Figure BDA0003197189920000089
and the temporary value of the LTE-U OFF duty ratio on the ith carrier when the carrier selection is carried out for a new LTE-U user. Since the user allocation and the LTE-UOFF duty cycle on each carrier can only be determined in the t +1 th cycle when all LTE-U users complete carrier selection, this temporary value is only related to the currently completed carrier selection result. Under the condition that the number of WiFi users is determined, if other LTE-U users select the ith carrier wave, the LTE-U ON duty ratio is increased along with the increase of the LTE-U users, so that the throughput requirement of the LTE-U users who have finished carrier wave selection, namely the following users can be guaranteedDoes not affect the result of the carrier selection of the previous user.
Under the assumption and analysis conditions, the component carrier selection problem considered by the present invention is to select a group of component carriers I with the minimum number for each LTE-U user arriving in the t-th CSAT period to meet the throughput requirement of the user, under the condition of ensuring coexistence fairness of the LTE-U system and the WiFi system and the throughput requirement of the existing LTE-U user in the network, that is:
optimizing the target:
Figure BDA0003197189920000091
constraint conditions are as follows:
Figure BDA0003197189920000092
wherein I denotes a group of component carriers selected for the LTE-U new user, C denotes the number of carriers selected for the LTE-U new user, and M denotes the upper limit of the number of selected carriers (C ≦ M); equation (4) indicates that any C-1 carriers cannot meet the throughput requirement of the new user and that there are C carriers that can meet the throughput requirement of the new user. If any M carriers cannot meet the throughput requirement of the new user, the user is refused to access the network.
When selecting a carrier for an LTE-U new user, firstly, judging whether a single carrier can meet the throughput requirement of the new user. If the carrier I exists, selecting the carrier i capable of providing the maximum throughput for the LTE-U new user from all single carriers capable of meeting the requirement*(ii) a If any single carrier can not meet the throughput requirement of the new user, sequentially increasing the number C of carrier selections until any C-1 carriers can not meet the throughput requirement of the new user and C carriers can meet the throughput requirement of the new user. If a plurality of groups of C carriers can meet the requirement, selecting a group of C carriers I which can provide the maximum total throughput for a new LTE-U user*(ii) a And if any M carriers cannot meet the throughput requirement of the new user, refusing the user to access the LTE-U system. Main steps of LTE-U new user carrier selectionAs shown in fig. 3, the description is as follows:
a) when a carrier is selected for a new LTE-U user, the throughput requirement of the user is firstly acquired
Figure BDA0003197189920000093
b) Calculate each CCiMaximum throughput currently available for new users
Figure BDA0003197189920000094
c) All N carriers are divided into
Figure BDA0003197189920000095
In descending order, i.e.
Figure BDA0003197189920000096
d) The initial value of the carrier selection number C is set to 1. If the first C carriers can meet the throughput requirement of the user, that is
Figure BDA0003197189920000097
The carrier selection of the user is finished; otherwise, sequentially increasing the number C of carrier selections until the first C carriers can meet the throughput requirement of the user. And if the first M carriers cannot meet the throughput requirement of the new user, rejecting the user to access the LTE-U system.

Claims (3)

1. A LTE-U system component carrier selection method facing throughput demand is characterized in that: the component carrier selection method comprises the following steps:
(1) initializing the number of coexisting network users at the beginning of the next CSAT period when the CSAT period begins: is provided with
Figure FDA0003607628530000011
Wherein t represents the current CSAT period, and t +1 represents the next CSAT period;
Figure FDA0003607628530000012
and
Figure FDA0003607628530000013
respectively representing the number of WiFi users and the number of LTE-U users needing service on the ith carrier wave in the coexistence network when the current CSAT period starts;
Figure FDA0003607628530000014
and
Figure FDA0003607628530000015
respectively representing the number of WiFi users and the number of LTE-U users needing service on the ith carrier wave in the coexisting network when the next CSAT period starts;
(2) in a CSAT period, according to the dynamic arrival or departure of users in the coexisting network, user information needing service on each carrier is updated: in the current CSAT period, if one user leaves the coexisting network after finishing transmission, the user is moved out of the corresponding user group on the carrier wave used by the user, and the user is paired with the corresponding user group
Figure FDA0003607628530000016
Or
Figure FDA0003607628530000017
Performing a subtraction operation; if a new user arrives at the coexisting network, firstly judging the type of the new user, if the user is a WiFi user, adding the user to the WiFi user group on the ith carrier wave used by the associated AP, and comparing the type of the new user with the type of the WiFi user group used by the associated AP
Figure FDA0003607628530000018
Performing an adding operation; if the user is an LTE-U user, the carrier is not immediately selected and distributed for the user, but the new user is recorded first, and the carrier selection is carried out for the user before the current period is finished;
(3) before the CSAT period ends, selecting suitable carriers for all new LTE-U users arriving in the period: before the current CSAT period is finished, according to the arrival time sequence of the LTE-U new users, selecting proper carriers for all the LTE-U new users arriving in the period in sequence;
in step (3), before the end of the current CSAT period, selecting suitable carriers for all new LTE-U users arriving in the period, which comprises the following specific processes:
a) when a carrier is selected for a new LTE-U user, the throughput requirement of the user is acquired firstly
Figure FDA0003607628530000019
b) Calculating each component carrier CCiMaximum throughput currently available for new users
Figure FDA00036076285300000110
c) All N carriers are divided into
Figure FDA00036076285300000111
In descending order, i.e.
Figure FDA00036076285300000112
d) Setting an initial value of the carrier selection number C to 1; if the first C carriers can meet the throughput requirement of the user, that is
Figure FDA00036076285300000113
The carrier selection of the user is finished; otherwise, sequentially increasing the number C of the carrier selection until the first C carriers can meet the throughput requirement of the user; if the first M carriers cannot meet the throughput requirement of the user, refusing the user to access the LTE-U system; m represents an upper limit of the number of carrier selections;
in step b), the ith component carrier CCiMaximum throughput currently available for new users
Figure FDA0003607628530000021
Comprises the following steps:
Figure FDA0003607628530000022
wherein
Figure FDA0003607628530000023
Is shown as
Figure FDA0003607628530000024
The system throughput that can be obtained when the WiFi system of an individual user alone occupies the ith carrier,
Figure FDA0003607628530000025
is shown as
Figure FDA0003607628530000026
The system throughput that can be obtained when the WiFi system of an individual user alone occupies the ith carrier,
Figure FDA0003607628530000027
representing the current throughput aggregate demand of the LTE-U user on the ith carrier,
Figure FDA0003607628530000028
indicating the system throughput that can be achieved when the LTE-U system alone occupies the ith component carrier,
Figure FDA0003607628530000029
a temporary value representing the LTE-U OFF duty cycle on the ith carrier at carrier selection for a new LTE-U user, this temporary value being related only to the currently completed carrier selection result.
2. The method for selecting LTE-U system component carriers oriented to throughput requirements of claim 1, wherein in the steps (1) - (3), a network architecture for fusing the LTE-U system and the WiFi system based on a network virtualization technology is adopted to share information between the LTE-U system and the WiFi system; the converged network architecture is described as follows:
one LTE-U subsystem and a plurality of WiFi subsystems coexist in an unauthorized frequency band; in the coexisting network, an LTE-U subsystem consists of a base station BS and a plurality of uniformly distributed user UEs, and each LTE-U user has a specific throughput requirement; each WiFi subsystem consists of an AP and a plurality of user STAs which are uniformly distributed; assume that the unlicensed band has N orthogonal component carriers, denoted CC1,CC2,…,CCN(ii) a Each CC may be shared by the LTE-U system and one WiFi system; each WiFi AP uses one carrier, and different WiFi APs use different carriers; the LTE-U BS can use all N carriers to provide service for the LTE-U user; downlink transmission of the LTE-U system adopts an OFDMA channel access mechanism of base station centralized scheduling to distribute time-frequency resources for users; the WiFi system adopts a CSMA/CA channel access mechanism based on the competition of 802.11n, and users access the channel in a competition mode; an F-CSAT mechanism based on time division multiplexing is adopted on each carrier wave to coordinate coexistence of the two systems;
respectively virtualizing physical entities in an LTE-U system and a WiFi system, namely an LTE-U BS and a WiFi AP, into corresponding virtualized network entities vBS and vAP, and managing the virtual entities through a software defined network technology; the LTE-U BS virtual network entity and the WiFi AP virtual network entity are uniformly controlled by an SDN controller, and the load intensity, the user throughput demand and the channel state of a wireless access network side are received from the LTE-U BS and the WiFi AP physical entity; the LTE-U BS can provide service for LTE-U users by using N carriers, and the LTE-U users have specific throughput requirements; the virtual entities intercommunicate the received information, and accordingly, a proper carrier is selected for the LTE-U user so as to meet the throughput requirement of the LTE-U user.
3. The method for selecting LTE-U system component carriers oriented to throughput requirements according to claim 1, wherein in step (2), the user information on the carrier is updated according to the dynamic arrival or departure of the user in the current CSAT period, and the specific process is as follows:
when the t CSAT period begins, the ith carrier wave in the coexisting network needs to be carried outThe number of WiFi users and LTE-U users to be served is respectively
Figure FDA0003607628530000031
And
Figure FDA0003607628530000032
setting:
Figure FDA0003607628530000033
in the tth CSAT period, a user leaves the coexistence network after completing transmission: if the user is a WiFi user, the user is moved out of the CC used by the useriWiFi user group on, namely:
Figure FDA0003607628530000034
no longer occupying CC in t +1 CSAT periodi(ii) a If the user is an LTE-U user, each CC in a carrier set used by the useriMove the user out of CCiLTE-U user group above, namely:
Figure FDA0003607628530000035
no longer occupying the carriers in the set in the t +1 CSAT period;
in the tth CSAT period, a new user arrives at the coexisting network: if the user is a WiFi user, firstly, the AP associated with the user is obtained, and then the user is added to the CC used by the associated APiWiFi user group on, namely:
Figure FDA0003607628530000036
making it contend for access channel from t +1 th period; if the user is an LTE-U user, the carrier is not immediately selected and allocated for the user, and the carrier selection is carried out until the period is finished.
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