CN104640230B - A kind of user equipment access method and user equipment - Google Patents
A kind of user equipment access method and user equipment Download PDFInfo
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Abstract
The invention discloses the cut-in methods of user equipment (UE) a kind of, comprising: determines the initial value of Backoff timer；Determine the UE resource block to be occupied (RB) number；The RB number to be occupied according to UE determines rollback step-length of the UE in time-domain, monitor the RB number of present channel free time, when the idle RB number monitored is greater than or equal to the UE RB number to be occupied, the numerical value of the Backoff timer is reduced by a rollback step-length, repeats this step until the Backoff timer is reset；And send data.The corresponding above method, the invention also discloses the internal structures of UE.
Description
Technical Field
The present application relates to the field of mobile communications technologies, and in particular, to a User Equipment (UE) access method and a UE in a cellular network.
Background
A conventional cellular network is a schedule-based system. In a conventional cellular network, when a UE has data to transmit, the UE needs to first transmit a scheduling request to a base station (eNB); after receiving the scheduling request, the eNB allocates uplink transmission resources to the UE and notifies the UE of the allocated resources through a dedicated control channel (PDCCH). The UE can transmit data after being notified of the resource allocation. The above-mentioned interactive procedure of sending scheduling request-allocating resource-notifying resource allocation result results in that the access delay of the UE in the scheduling-based system needs at least 11 ms and cannot be further reduced. Such a long access delay is desirable in conventional cellular networks. However, with the continuous emergence of new services, the problem that the access delay of the scheduling-based access mechanism is long and cannot be reduced will become more and more obvious. For example, from the service perspective, a cloud service in the future will be developed in large quantities, and the processing delay caused by the extra processing of the cloud and the increase of the transmission delay of data will cause the user to be more sensitive to the end-to-end delay. In this case, if the access delay of the UE in the cellular network can be reduced, the processing delay of the device and the transmission delay of the data can be compensated to a large extent. Therefore, how to reduce the access delay of the UE in the cellular network has become an important research topic at present.
Disclosure of Invention
The invention discloses a UE access method, which aims to reduce the access time delay of UE.
The access method of the UE comprises the following steps: determining an initial value of a back-off timer; determining the number of Resource Blocks (RBs) to be occupied by the UE; determining a backoff step of the UE in a time domain according to the number of RBs to be occupied by the UE, monitoring the number of idle RBs on a current channel, reducing the numerical value of the backoff timer by one backoff step when the monitored number of idle RBs is greater than or equal to the number of RBs to be occupied by the UE, and repeatedly executing the step until the backoff timer is cleared; and transmitting the data.
Wherein determining an initial value of a back-off timer comprises: determining a size CW of a contention window; determining the time slot number a of the UE needing to back off in a time domain, and setting the initial value of a back-off timer as a; where a is a random number with a value between 1 and CW.
Wherein determining the size CW of the contention window comprises: the base station monitors the load in the cell; when the base station finds that the load is heavy in the cell, the base station broadcasts the number of the UE in the current cell; when the base station finds that the load in the cell is not heavy, the base station broadcasts the current system utilization rate; when receiving the number of the UE in the current cell, the UE determines a contention window value according to the system saturation state; when receiving the system utilization, the UE determines the contention window value according to the system non-saturation state.
The determining the number of Resource Blocks (RBs) to be occupied by the UE comprises the following steps: and obtaining a derivative of the link delay of the UE, determining the value of the variable of the number of RBs occupied by the UE when the derivative of the link delay of the UE is zero, and taking the value as the number of RBs occupied by the UE.
The link delay of the UE is calculated by the following formula: delayUE＝Tbackoff+TtransmissionWherein, TbackoffIs a backoff delay; t istransmissionIs the transmission delay.
Backoff delay Tbackoff is calculated by the following formula:wherein RB _ total _ idle is the monitored total number of free RBs; RB _ selected is the number of RBs to be occupied by the UE; a slot is a time of one slot.
Backoff delay TbackoffCalculated by the following formula:wherein RB _ total _ idle is the monitored total number of free RBs; RB _ selected is the number of RBs to be occupied by the UE; a slot is a time of one slot.
Transmission time delay TtransmissionCalculated by the following formula:wherein, Transmission _ size is the total length of all packets in the queue or the length of the maximum Transmission unit or the size of the Transmission packet converted from the maximum Transmission time; m is the transmission rate of a single RB determined by the selected coded modulation scheme.
Determining a backoff step size of the UE in the time domain according to the number of RBs to be occupied by the UE comprises: the backoff step is a value obtained by rounding a quotient of the monitored total number of idle RBs and the number of RBs to be occupied by the UE.
Wherein sending the data comprises: and selecting the resource blocks occupied by the UE from all the current idle RBs according to the number of the resource blocks occupied by the UE, and transmitting data by using the selected resource blocks occupied by the UE.
The above method further comprises: after determining the size CW of the contention window, the UE transmits a sounding reference signal SRS to the base station; the base station judges the correlation of the channels between the UE according to the SRS reported by the UE and sends a competition window adjustment instruction to the UE; and the UE adjusts the size of the contention window according to the contention window adjustment instruction.
An embodiment of the present invention further provides a UE, including:
a back-off timer initialization unit, configured to determine an initial value of a back-off timer;
a resource block RB number determining unit, configured to determine the number of resource blocks RB to be occupied by the UE;
a backoff unit, configured to determine a backoff step of the UE in the time domain according to the number of RBs to be occupied by the UE, monitor the number of RBs idle in the current channel, reduce the value of the backoff timer by one backoff step when the monitored number of RBs idle is greater than or equal to the number of RBs to be occupied by the UE, and repeatedly execute the step until the backoff timer is cleared; and
and the data sending unit is used for sending data.
In particular, an embodiment of the present invention further provides a contention window adjustment method, including: the base station monitors the load in the cell; when the base station finds that the load is heavy in the cell, the base station broadcasts the number of the UE in the current cell; when the base station finds that the load in the cell is not heavy, the base station broadcasts the current system utilization rate; when receiving the number of the UE in the current cell, the UE determines a contention window value according to the system saturation state; when receiving the system utilization, the UE determines the contention window value according to the system non-saturation state.
It can be seen from the above procedure of the UE access method and the structure of the UE that the UE can dynamically adjust the step length of the UE returning in the time domain according to the number of RBs to be occupied by the UE and the detected number of free RBs on the current channel, so that the UE can quickly complete the returning in the time domain when the number of RBs occupied by the UE is small and/or the number of free RBs is large, reduce the access delay, and implement the quick access of the UE.
Drawings
Fig. 1 is a flowchart of a UE access method according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a process of a plurality of UEs contending for a channel when the UE access method shown in FIG. 1 is applied;
fig. 3 is a signaling flow chart of a UE access method according to an embodiment of the present invention;
fig. 4 is a flowchart of a UE access method according to another embodiment of the present invention; and
fig. 5 is a schematic diagram of an internal structure of a UE according to an embodiment of the present invention.
Detailed Description
As mentioned above, with the emergence of new services, the end-to-end delay of the user for the new services will be more sensitive, so if the access delay of the UE can be reduced, the processing delay of the device and the transmission delay of data can be compensated to a great extent.
In addition, from the topology of the network, in the future, in order to expand the system capacity, more and more small cells (small cells) are added under the original macro base station. Under the topology, the number of UEs under the micro base station corresponding to each small cell is far smaller than that of the original macro base station. The contention conflict problem is not very obvious if a Contention Based (CB) UE access scheme is introduced at the micro base station side.
Based on the above two aspects, the present invention proposes to introduce a contention-based UE access method in a small cell. In fact, the contention-based UE access mechanism is a widely used access mechanism, and currently, a Wireless Local Area Network (WLAN) system is based on the contention mechanism. However, since there is a great difference between WLAN and Long Term Evolution (LTE) system in physical layer, the existing contention-based UE access mechanism is not applied directly in LTE. Specifically, the largest difference between LTE and WLAN on the physical layer is that the subcarrier width of WLAN is 312.5kHz, and its corresponding Orthogonal Frequency Division Multiplexing (OFDM) symbol length is 4 microseconds (μ s); while the subcarrier width of LTE is only 15kHz, and the corresponding OFDM symbol length is 71 mus. In a slot-based contention system, the length of one slot should be at least greater than the length of one OFDM symbol. In a WLAN, one slot is 9 μ s long, allowing for uplink and downlink switching. Then in LTE systems a slot is also at least 71 us. Such a long slot value causes idle delay in contention and a cost after collision to become very large, which has become the biggest problem of introducing a contention mechanism in LTE.
In order to solve the problem, the invention provides a UE access method, which solves the problem that the idle delay and the cost after collision during contention caused by the long slot length in the LTE system become very large by increasing the backoff (backoff) speed in the time domain.
In one embodiment of the invention, the problem of too long backoff time in the time domain is made up by increasing the backoff in frequency mainly in consideration of the orthogonal frequency division access characteristics of LTE/LTE-A. It is known to those skilled in the art that in a WLAN system, once a UE gets an opportunity to occupy a channel, the UE will occupy the whole bandwidth, and in an embodiment of the present invention, to implement a backoff on frequency, the UE first determines the number of subcarriers occupied by itself according to its own requirement. Hereinafter, for convenience of description and uniformity with the LTE system, the above subcarriers are replaced with Resource Blocks (RBs). That is, in the embodiment of the present invention, the UE may determine the number of RBs occupied by itself according to its own requirement. After successful contention, the UE will only occupy the number of RBs required by itself. In the present invention, this manner is referred to as back-off in the frequency domain. In particular, the UE considers that the backoff is larger in the frequency domain as the number of RBs to be occupied by the UE is smaller; the more RBs the UE is to occupy, the smaller the backoff in the frequency domain. Accordingly, if the UE has a larger backoff in the frequency domain, the UE may have a faster backoff in the time domain; and if the UE has a smaller backoff in the frequency domain, the UE should have a slower backoff in the time domain. That is, if the number of RBs to be occupied by the UE is smaller, the backoff step of the UE in the time domain may be increased, so that the UE may complete backoff in the time domain more quickly; and if the UE occupies more RBs, the backoff step of the UE in the time domain should be reduced more, so that the UE can complete the backoff in the time domain more slowly. In particular, when the UE chooses to occupy the whole bandwidth, it considers that it has no backoff in the frequency domain, and the backoff step size of the UE in the time domain remains 1 as in the conventional WLAN.
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a UE access method according to an embodiment of the present invention. As shown in fig. 1, the access method described in this embodiment mainly includes:
step 101: an initial value of a back-off timer is set.
Specifically, this step can be realized by the following steps:
the first step is as follows: the size CW of the contention window is determined.
According to the currently actually used WLAN protocol, the size of the contention window is defaulted to 31 slots. Thus, in this embodiment, the CW may be any predetermined fixed value, such as 31 slots.
The second step is that: determining the time slot number a which the UE needs to back off in the time domain, and setting the initial value of the back-off timer to a.
In this step, the UE generates a random number a with a value between 1 and CW before transmitting the packet.
It is known that under the existing contention-based UE access mechanism, the UE will continuously monitor the channel, and send its own data packet only after finding that the channel accumulation is a slots empty.
Step 102: determining the number of RBs to be occupied by the UE.
In this step, the number of RBs to be occupied by the UE directly affects the waiting delay and transmission delay of the data packet. For example, if the number of RBs to be occupied by the UE is large, the waiting delay of the data packet will increase, and the transmission delay thereof will decrease; if the number of RBs to be occupied by the UE is small, the waiting delay of the packet is reduced, and the transmission delay thereof is increased. Therefore, in this step, a value of the number of RBs can be selected to minimize the overall link delay of the packet, i.e., the overall delay from the time the packet enters a Medium Access Control (MAC) queue until the base station receives the packet. In other words, the number of RBs to be occupied by the UE will be determined with the final goal of optimizing the link delay in one embodiment of the invention. It should be noted that the above optimization objective is only one specific embodiment of determining the number of RBs to be occupied by the UE, and in practical applications, other optimization objectives may also be selected to determine the number of RBs to be occupied by the UE according to the requirements of an actual system.
How to determine the number of RBs to be occupied by the UE will be described in detail below by a specific example.
In this example, the link delay of the UE mainly consists of three parts, namely, the link delay Dela of the UEyUECan be calculated by the following formula (1):
DelayUE＝Tbackoff+Ttransmission+Tfrozen （1）
wherein, TbackoffTo back off delay, when the UE senses that the channel is idle, its back off timer is decremented by a step value. Backoff delay TbackoffIs the time required from the start of the backoff to the backoff timer being 0. T isfrozenTo freeze the delay for the back-off timer, when a UE monitors that other UEs occupy the channel, it freezes its own back-off timer. Back-off timer freezing delay TfrozenNamely a backspacing meterThe total length of time the timer freezes. T istransmissionThe transmission delay is the time from the UE sending the data packet to the base station receiving the data packet.
Wherein, the back off delay TbackoffThe calculation can be performed according to the mean value, and can also be performed according to the real-time back-off delay. If calculated according to the mean value, the following formula (2) shows:
if the real-time backoff delay is calculated, the following formula (3) is shown:
where a = random (1, CW), i.e. a is a random number whose value is between 1 and CW; wherein RB _ total _ idle is the monitored total number of free RBs; RB _ selected is the number of RBs to be occupied by the UE; slot is the time of a slot, which can take 71 μ s in LTE systems.
In addition, the transmission delay TtransmissionCan be calculated by the following formula (4):
wherein, Transmission _ size depends on the specific Transmission scheme, and its value can be the total length of all packets in the queue, or the length of the maximum Transmission unit, which is similar to the Maximum Transmission Unit (MTU) in the WLAN, or the size of the Transmission packet converted from the maximum Transmission time (similar to the contention stream Transmission opportunity (TxOP) in the WLAN), etc.; m is the transmission rate of a single RB determined by the selected coded modulation scheme. For example, in the case of single antenna in LTE, when 64QAM and 3/4 code rates are selected, the transmission rate m of a single RB is 0.76 Mbps.
When RB _ selected is smaller than RB _ total _ idle, the timer will go back by a specific step size, so the delay T will be frozen in this embodimentfrozenIs noted as 0, i.e. Delay in this caseUE＝Tbackoff+Ttransmission。
Based on the above description, it is found through research that the convex optimization problem of reducing the link delay is only one variable RB _ selected. An optimal solution of the univariate convex optimization problem only needs to be carried out on the link Delay of the UEUEThe derivative is obtained.
Therefore, in this step, the Delay can be first processedUETaking the derivative, determining the order DelayUEThe value of RB _ selected when the derivative of (c) is zero is taken as the number of RBs to be occupied by the UE.
Step 103: and determining the backoff step of the UE on the time domain according to the number of RBs to be occupied by the UE.
In this step, a backoff step of the UE in the time domain may be determined by the following formula (5). It should be noted that the backoff step size of the UE in the time domain should be a value rounded to the calculation result of the following formula (5).
After determining the number of RBs occupied by the UE, the phase of entering the contention channel can be started.
Step 104: and monitoring the number of the idle RBs of the current channel, reducing the numerical value of the backoff timer by a backoff step when the monitored number of the idle RBs is greater than or equal to the number of the RBs to be occupied by the UE, and then returning to the step 103 until the backoff timer is zero. Namely, when the back-off timer is cleared, step 105 is executed; and returns to step 103 when the back-off timer is not cleared.
In this step, if the back-off step is larger than the current value of the back-off timer, the back-off timer is directly cleared.
Step 105: and sending the data.
In this step, when the back-off timer is zero, the UE may choose RB _ selected RBs from all currently idle RBs to send data. Specifically, the UE may use a random selection scheme, or may select the RBs according to a predetermined criterion, for example, selecting the best performing RBs.
How a plurality of UEs coordinate to operate under the contention-based UE access mechanism is described in detail below by using a specific example. Assuming that there are 3 UEs in the small cell, the total number of RBs of the system is 10. Assume that the optimum value of the contention window CW is 7. Based on the contention window value, the number of random backoff slots generated by UE a is 6; the number of random backoff time slots generated by the UE B is 4; the number of random backoff slots generated by UE C is 5. Next, each UE calculates the number of RBs needed by itself according to the above-described method, according to the service and other conditions of itself. In the example, it is assumed that UE a needs to occupy 5 RBs for one transmission, UE B needs to occupy 3 RBs for one transmission, and UE C needs to occupy 1 RB for one transmission. Assuming that these 3 UEs start to back off at the same time, their contention for the channel will be as shown in fig. 2.
As shown in fig. 2, 3 UEs start to back-off at slot0 at the same time. They each initially detect that 10 RBs on the channel are free. Since the number of RBs occupied by UE C is 1, the backoff step of UE C is 10; and its random backoff slot number is 5, so the backoff counter of UE C becomes 0 only after one slot. UE C may then select an RB to transmit data at slot 1. For UE a and UE B, since they have a larger number of RBs they determine to occupy themselves, they must continue to wait for the backoff counter to be cleared. At slot1, UE B listens that there are 9 more RBs idle, and the number of self-occupied RBs is 3, so the backoff step of UE B is 3. Similarly, the backoff step size of UE a is 1. As shown in fig. 2, in each slot, each UE adjusts its backoff step according to the monitored number of free RBs and the number of RBs occupied by itself. And selecting the RB from the idle RBs to transmit data until the self backoff counter is cleared.
In the UE access method, the backoff step of the UE in the time domain can be dynamically adjusted according to the number of RBs to be occupied by the UE and the detected number of idle RBs on the current channel, so that the UE can quickly finish backoff in the time domain when the number of RBs occupied by the UE is small and/or the number of idle RBs is large, the access delay is reduced, and the UE can be quickly accessed.
It should be noted that, in the first step of step 101 in the above embodiment, the size CW of the contention window may be further optimized based on an access delay mathematical model of the contention access system. At present, the access delay mathematical model analysis aiming at the competitive access system is relatively mature: one is access delay analysis in a saturation state; another is access delay analysis in the unsaturated state. The saturation state is that each UE is assumed to have an infinite number of packets to send at any time. While the analysis of the unsaturated state generates data packets according to the true traffic model and satisfies the assumption that the traffic volume (also called cell load) of all UEs in the cell is less than the saturated throughput of the whole system. According to the analysis result of the mathematical model, the number of the UEs in the saturation state is a key factor influencing the optimal competition window value. In the unsaturated state, the cell load and the number of UEs are both key factors affecting the optimal contention window value, and the influence of the cell load is more important than that of the UE in the unsaturated state.
Based on the above combination of knowledge, the embodiment of the present invention provides a contention window adjustment method, which can be applied in the first step of step 101 described above for determining the size of the contention window. The method specifically comprises the following steps:
first, a base station (small cell base station) monitors an intra-cell load; when the base station finds a heavy load in the cell (for example, when the system utilization rate is greater than or equal to 0.7), the base station broadcasts the number of the UEs in the current cell; and when the base station finds that the intra-cell load is not heavy (e.g., the system utilization is less than 0.7), the base station broadcasts the current system utilization (load/saturation throughput) ρ. When receiving the number of the UE in the current cell, the UE determines a contention window value according to the system saturation state; and when receiving the system utilization rate rho, the UE determines a contention window value according to the system non-saturation state.
Specifically, when the load in the cell is heavy (for example, the system utilization rate is greater than or equal to 0.7), the traffic flow model of the users in the cell can be considered to be similar to the full-buffer model. Then the calculation of the optimal CW can be performed using the following equation (6):
wherein,pcollision＝1-(1-psend)N-1，n denotes the number of users in the cell, MTU denotes the maximum transmission unit, and Data _ rate is the transmission rate of the system.
When the load in the cell is light (for example, the system utilization rate is less than 0.7), the optimal CW needs to be calculated according to the specific service model of the user. In this embodiment, the optimal CW value may be obtained by deriving the relationship between the access delay and the CW. Simulation verification shows that when the load in a cell is heavy, the deviation between the optimal CW obtained by mathematical analysis and the optimal CW obtained by simulation is large by adopting the method. Therefore, this method is used only when the load in the cell is light. The following equation (7) gives the access delay d of user iiRelationship to contention window:
where N denotes the number of users, C denotes the service rate of the system (i.e. the transmission rate of the physical layer), P denotes the size of the maximum transmission unit, ρ denotes the maximum utilization of the system in saturation (this value is related to CW and can be obtained under full-buffer assumption), ω denotes the maximum utilization of the system in saturation, andiandthe first and second moments respectively represent the packet size distribution. The purpose of this embodiment is to find the CW setting with the smallest average access delay, hence according to diThe average access delay as shown in equation (8) is obtained.
Since the optimization problem of minimizing the average access delay is only one variable of CW, the optimal CW value can be calculated by only obtaining the derivative of formula (8) and setting the derived expression to 0.
The embodiment of the invention also provides a signaling flow applying the method, as shown in fig. 3.
In step 301, the UE sends a random access preamble (preamble) to a base station (e.g., a micro base station);
in step 302, the base station sends an instruction to the UE to perform timing adjustment;
the above steps 301 and 302 may refer to a UE synchronization mechanism in an LTE system.
In step 303, the base station sends a system information block to the UE, including information such as the number of UEs in its cell and the system utilization;
in step 304, the UE determines a contention window value CW according to a system information block transmitted by the base station;
in step 305, the UE determines the number of RBs to be occupied and a backoff step size, monitors a channel, and performs backoff until the backoff counter reaches zero when it is monitored that the number of idle RBs is greater than the number of RBs to be occupied;
in step 306, the UE selects an RB occupied by itself from the idle RBs;
in step 307, the UE transmits data.
In the above procedure, when the channel correlation is high, when selecting the RB occupied by itself, if the UE criterion is the best selective RB, then there is a high possibility that a collision may easily occur between UEs having high correlation.
To solve this problem, after determining the contention window value CW in step 304, the UE may further send a Sounding Reference Signal (SRS) to the base station, so that the base station may determine the inter-UE channel correlation according to the SRS reported by the UE and further send a contention window adjustment indication to the UE, and then the UE may adjust the size of the contention window according to the contention window adjustment indication. For example, when the channel correlation between UEs is large, the problem of too high collision is avoided by enlarging the contention window.
It can be seen from the above contention window adjustment method that, in the method of the present invention, the size CW of the contention window can be optimized according to the number of UEs in the cell and the traffic of the UEs, so that the size of the contention window is appropriately increased when the number of UEs in the cell is large and/or the traffic of the UEs is heavy, so as to reduce the probability of contention collision; and when the number of the UEs in the cell is small and/or the traffic of the UEs is light, the size of the contention window is properly reduced so as to reduce the access delay of the UEs.
It should be noted that the above contention window adjusting method may also be directly applied to the existing contention-based UE access method, and may also reduce the access delay of the UE. Another embodiment of the present invention provides such a UE access method, and a specific flow thereof is shown in fig. 4. The method mainly comprises the following steps:
step 401: the size CW of the contention window is determined according to the load of the cell.
Step 402: and determining the time slot number a which the UE needs to back off in the time domain.
In this step, the UE generates a random number a with a value between 1 and CW before transmitting the packet.
Step 403: monitoring the channel, and sending a data packet of the channel after monitoring that the channel accumulation is empty by a time slots.
According to the UE access method, an embodiment of the present invention further discloses a UE, which has a structure as shown in fig. 5 and mainly includes:
a back-off timer initialization unit 501, configured to determine an initial value of a back-off timer; specifically, the back-off timer initialization unit 501 may first determine the size CW of the contention window, determine the number a of timeslots that the UE needs to back off in the time domain, and set the initial value of the back-off timer to a; wherein a is a random number with a value between 1 and CW;
an RB number determining unit 502, configured to determine the number of RBs of a resource block to be occupied by the UE;
a backoff unit 503, configured to determine a backoff step of the UE in the time domain according to the number of RBs to be occupied by the UE, monitor the number of RBs idle in the current channel, reduce the value of the backoff timer by one backoff step when the monitored number of RBs idle is greater than or equal to the number of RBs to be occupied by the UE, and repeatedly execute this step until the backoff timer is cleared; and
a data transmitting unit 504, configured to transmit data.
Further, the back-off timer initialization unit 501 may determine the size CW of the contention window according to the contention window adjustment method.
The number of resource blocks RB determination unit 502 may determine the number of resource blocks RB to be occupied by the UE according to step 103 described above.
The back-off unit 503 may perform back-off in the time domain according to the above steps 104 and 105 until the back-off timer is cleared.
As described above, the UE may dynamically adjust the step length of the UE in the time domain according to the number of RBs to be occupied by the UE and the detected number of RBs idle in the current channel, so that the UE can quickly complete the backoff in the time domain when the number of RBs occupied by the UE is small and/or the number of RBs idle is large, reduce the access delay, and implement the fast access of the UE.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (13)
1. An access method of a User Equipment (UE), comprising:
determining an initial value of a back-off timer;
determining the number of Resource Blocks (RBs) to be occupied by the UE;
determining a backoff step of the UE in a time domain according to the number of RBs to be occupied by the UE, monitoring the number of idle RBs on a current channel, reducing the numerical value of the backoff timer by one backoff step when the monitored number of idle RBs is greater than or equal to the number of RBs to be occupied by the UE, and repeatedly executing the step until the backoff timer is cleared; and
and sending the data.
2. The UE access method of claim 1, wherein the determining an initial value of a backoff timer comprises:
determining a size CW of a contention window;
determining the time slot number a of the UE needing to back off in a time domain, and setting the initial value of a back-off timer as a; where a is a random number with a value between 1 and CW.
3. The UE accessing method according to claim 2, wherein the determining the size CW of the contention window comprises:
the base station monitors the load in the cell;
when the base station finds that the load is heavy in the cell, the base station broadcasts the number of the UE in the current cell; when the base station finds that the load in the cell is not heavy, the base station broadcasts the current system utilization rate; and
when receiving the number of the UE in the current cell, the UE determines a contention window value according to the system saturation state;
when receiving the system utilization, the UE determines the contention window value according to the system non-saturation state.
4. The UE accessing method of claim 1, wherein the determining the number of RBs to be occupied by the UE comprises: and obtaining a derivative of the link delay of the UE, determining the value of the variable of the number of RBs occupied by the UE when the derivative of the link delay of the UE is zero, and taking the value as the number of RBs occupied by the UE.
5. The UE accessing method according to claim 4, wherein the link delay of the UE is calculated by the following formula:
DelayUE＝Tbackoff+Ttransmission
wherein, TbackoffIs a backoff delay; t istransmissionIs the transmission delay.
6. The UE accessing method of claim 5, wherein the backoff delay T isbackoffCalculated by the following formula:
wherein CW is the size of the contention window, RB _ total _ idle is the monitored total number of free RBs; RB _ selected is the number of RBs to be occupied by the UE; a slot is a time of one slot.
7. The UE accessing method of claim 5, wherein the backoff delay T isbackoffCalculated by the following formula:
wherein a is an initial value of the back-off timer, and RB _ total _ idle is the monitored total number of idle RBs; RB _ selected is the number of RBs to be occupied by the UE; a slot is a time of one slot.
8. The UE accessing method of claim 5, wherein the transmission delay T istransmissionCalculated by the following formula:
wherein, the transmisssio _ n size is the total length of all packets in the queue or the length of the maximum transmission unit or the size of the transmission packet converted from the maximum transmission time; RB _ selected is the number of RBs to be occupied by the UE; m is the transmission rate of a single RB determined by the selected coded modulation scheme.
9. The UE accessing method of claim 1, wherein the determining the backoff step size of the UE in the time domain according to the number of RBs to be occupied by the UE comprises: the backoff step is a value obtained by rounding a quotient of the monitored total number of idle RBs and the number of RBs to be occupied by the UE.
10. The UE access method of claim 1, wherein the sending data comprises: and selecting the resource blocks occupied by the UE from all the current idle RBs according to the number of the resource blocks occupied by the UE, and transmitting data by using the selected resource blocks occupied by the UE.
11. The UE access method of claim 2, further comprising: after determining the size CW of the contention window, the UE transmits a sounding reference signal SRS to the base station; the base station judges the correlation of the channels between the UE according to the SRS reported by the UE and sends a competition window adjustment instruction to the UE; and the UE adjusts the size of the contention window according to the contention window adjustment instruction.
12. The UE accessing method according to claim 2, wherein the determining the size CW of the contention window comprises:
the base station monitors the load in the cell;
when the base station finds that the load is heavy in the cell, the base station broadcasts the number of the UE in the current cell; when the base station finds that the load in the cell is not heavy, the base station broadcasts the current system utilization rate; and
when receiving the number of the UE in the current cell, the UE determines the size CW of a contention window according to the system saturation state;
upon receiving the system utilization, the UE determines the size CW of the contention window according to the system non-saturation state.
13. A User Equipment (UE), comprising:
a back-off timer initialization unit, configured to determine an initial value of a back-off timer;
a resource block RB number determining unit, configured to determine the number of resource blocks RB to be occupied by the UE;
a backoff unit, configured to determine a backoff step of the UE in the time domain according to the number of RBs to be occupied by the UE, monitor the number of RBs idle in the current channel, reduce the value of the backoff timer by one backoff step when the monitored number of RBs idle is greater than or equal to the number of RBs to be occupied by the UE, and repeatedly execute the step until the backoff timer is cleared; and
and the data sending unit is used for sending data.
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| CN106559907A (en) | 2015-09-24 | 2017-04-05 | 株式会社Ntt都科摩 | Determine method, wireless base station and the mobile station of contention window size |
| CN109804702B (en) * | 2016-08-12 | 2024-03-15 | 瑞典爱立信有限公司 | LBT parameters for SRS transmission |
| CN109257794B (en) * | 2017-07-13 | 2021-06-01 | 华为技术有限公司 | Random access method and equipment |
| CN110719649B (en) * | 2018-07-12 | 2023-02-10 | 华为技术有限公司 | Channel access method and device |
| CN112188545B (en) * | 2019-07-02 | 2022-12-09 | ***通信集团山东有限公司 | Access control method, device, storage medium and base station |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101316134A (en) * | 2007-05-31 | 2008-12-03 | 大唐移动通信设备有限公司 | Accidental access method and corresponding terminal and base station adopting the same |
| CN102378364A (en) * | 2010-08-24 | 2012-03-14 | 中兴通讯股份有限公司 | Random access method and system realizing same |
| WO2012064775A1 (en) * | 2010-11-08 | 2012-05-18 | Qualcomm Incorporated | System and method for radio access network overload control |
| CN102823316A (en) * | 2010-03-05 | 2012-12-12 | 英特尔公司 | Contention-based transmission with contention-free feedback for reducing latency in lte advanced networks and enhanced pucch |
| WO2013107365A1 (en) * | 2012-01-17 | 2013-07-25 | 电信科学技术研究院 | Access control method and apparatus |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20040064867A (en) * | 2003-01-10 | 2004-07-21 | 삼성전자주식회사 | Method for providing random access effectively in mobile telecommunication system |
| JP4477022B2 (en) * | 2007-02-27 | 2010-06-09 | 日本電信電話株式会社 | Wireless base station, wireless node, wireless communication system, and wireless communication method |
| JP2008252565A (en) * | 2007-03-30 | 2008-10-16 | Nec Corp | Wireless terminal and communication control method of wireless terminal |
-
2013
- 2013-11-06 CN CN201310545032.5A patent/CN104640230B/en active Active
-
2014
- 2014-10-31 JP JP2014222942A patent/JP6437273B2/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101316134A (en) * | 2007-05-31 | 2008-12-03 | 大唐移动通信设备有限公司 | Accidental access method and corresponding terminal and base station adopting the same |
| CN102823316A (en) * | 2010-03-05 | 2012-12-12 | 英特尔公司 | Contention-based transmission with contention-free feedback for reducing latency in lte advanced networks and enhanced pucch |
| CN102378364A (en) * | 2010-08-24 | 2012-03-14 | 中兴通讯股份有限公司 | Random access method and system realizing same |
| WO2012064775A1 (en) * | 2010-11-08 | 2012-05-18 | Qualcomm Incorporated | System and method for radio access network overload control |
| WO2013107365A1 (en) * | 2012-01-17 | 2013-07-25 | 电信科学技术研究院 | Access control method and apparatus |
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| JP6437273B2 (en) | 2018-12-12 |
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