CN111601360B - Relay selection method in millimeter wave communication system - Google Patents
Relay selection method in millimeter wave communication system Download PDFInfo
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- H04W40/00—Communication routing or communication path finding
- H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
- H04W40/22—Communication route or path selection, e.g. power-based or shortest path routing using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
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Abstract
The invention belongs to the technical field of millimeter wave communication, and particularly relates to a relay selection method in a millimeter wave communication system. The technical scheme of the invention is that a new load factor broadcast is added as a part of system information on the basis of the existing relay search and selection scheme based on the received power, and a strong access control method is configured for the network, thereby being beneficial to load balance and effectively utilizing the frequency spectrum resource of millimeter waves. Secondly, the relay search and selection strategy is obtained based on the optimal stopping theory, and the connection threshold value is optimized, so that the throughput of the relay search and the millimeter wave communication selected by using the strategy is optimal.
Description
Technical Field
The invention belongs to the technical field of millimeter wave communication, and particularly relates to a relay selection method in a millimeter wave communication system.
Background
A multi-relay millimeter wave communication network is shown in fig. 1. MmWave, as a significant feature in 5G networks, makes direct communication between UEs susceptible to being blocked. When direct communication between UEs is not possible, communication may be performed by means of a relay. And the high-density relay deployment scheme in the 5G network enables a large number of available relays to exist around the UE. The UE needs to perform basic relay search and selection before communicating via the relay. Relay search typically involves two steps: (1) searching and acquiring synchronization with the relay, (2) decoding system information containing basic information for accessing the relay. In relay search, the UE should search for the relay with the strongest received power. Once the UE finds a suitable relay, it may select the relay to continue communication. Relay selection based on received power may lead to a load imbalance problem for the network in a multi-layer heterogeneous network furthermore, MmWave communication utilizes a large amount of spectrum resources in the MmWave frequency band (30-300GHz) to achieve multi Gbps data rates. In 5G networks, the load imbalance problem may become more severe, which will make the abundant radio resources brought by the millimeter wave spectrum under-utilized.
For conventional relay search and selection techniques, a scheme of selecting the maximum received power as a communication relay is generally adopted. Repeating broadcast of synchronization signal and system information, the synchronization signal having period T syn And seconds. There may be L transmit-receive spatial signature pairs in the synchronization process. Assume that the UE learns the beamforming direction from detecting the relay synchronization signal. Assume that there are 30 relays around the UE and that these relays may have established connections with a large number of active UEs.
As shown in fig. 2, the specific steps of the relay search and selection based on the maximum received power are as follows:
first, the UE checks the first relay for the beamforming scan period LT syn After which time synchronization is obtained and the beam forming direction is determined. The UE then measures the corresponding SNR received from the relay.
If the received SNR measured from the current relay is below a certain SNR threshold Γ, the UE stops checking the current relay and starts checking another relay. Otherwise, the UE records the receiving power of the current relay.
Then, the UE checks each relay, and records the received power for the relay that satisfies the lowest communication snr until the 30 th relay is checked.
And finally, the UE selects the maximum relay in the recorded receiving power to carry out random access, and starts data communication.
Problems with this conventional approach include: firstly, when the UE searches for and selects the relay, the number of active UEs to which the relay has been connected is not considered, which may cause a problem of load imbalance in the communication network, and the number of micro relay connections having low power but working in the millimeter wave spectrum is very small, which may cause load imbalance in the millimeter wave network and waste millimeter wave spectrum resources. Secondly, since all relays around the UE are checked for relay search and selection in each communication cycle of the UE, much time is wasted by the UE in checking the relays, so that the effective communication time in the communication cycle is reduced, and the throughput is reduced. Finally, due to factors such as time-varying radio environment, UE mobility, and clock drift, synchronization of the UE with previously checked relays may become outdated, resulting in failed communication access.
Disclosure of Invention
The present invention aims to solve the above problems by providing a relay selection method based on load sensing and optimal stop theory.
The technical scheme of the invention is as follows: a relay selection method in a millimeter wave communication system, the millimeter wave communication system comprising a source user, a plurality of relays and a sink user, wherein the relays are used for signal transmission and reception, the source user is used for signal transmission, and the sink user is used for signal reception; the method specifically comprises the following steps:
s1, source user detects the synchronization signal of ith relay broadcast, the synchronization signal includes relay load information, and SNR received from relay i is measured i If the value is greater than the set threshold value Γ, the process proceeds to step S2, otherwise, the j-th relay is selected, i ≠ j, i ═ j is updated, and the step S1 is repeated;
s2, the source user extracts the load information of the relay i from the synchronous signal to obtain the expected scheduling probability beta i ：
β i ＝1/(M i +1)
Wherein M is i Number of active users serving relay i;
s3, calculating selection metric R of relay i by source user i ：
R i ＝β i log(1+SNR i )
S4, judgment of R i If the current value is greater than or equal to the connection threshold value mu, if so, the step S5 is performed, otherwise, the source user selects the jth relay, i ≠ j, updates i ═ j, and returns to the step S1;
the calculation formula of the connection threshold value mu is as follows:
wherein W is the channel bandwidth and lambda is the optimum throughputThe discharge quantity is calculated by the following method: setting an initial value lambda of optimal throughput * (0) K is any value greater than 0, iteratively:
t is the number of iterative calculation rounds, and the initial value is 0. T is ra Requiring a fixed time, T, for the random access procedure data Assuming desired selection metrics for relays for data transmission duration of source user and relay communication
As independent and identically distributed random variables
Having a cumulative distribution function of
Cumulative distribution function
Wherein x is
Possible values of (a). The probability that each relay SNR does not fall below the threshold Γ is the same, and is p,
T syn for relaying the period of the broadcast synchronization signal, T sib The period of a system information block containing relay load information in a synchronization signal; after iteration till convergence, the convergence value is taken as the optimal throughput lambda * ；
And S5, selecting the relay i by the source user, and establishing connection between the source user and the sink user and the selected relay i to perform data communication.
The technical scheme of the invention is that a new load factor broadcast is added as a part of system information on the basis of the existing relay search and selection scheme based on the received power, and a strong access control method is provided for the network, thereby being beneficial to load balance and effectively utilizing the frequency spectrum resources of millimeter waves. Secondly, the relay search and selection strategy is obtained based on the optimal stopping theory, and the connection threshold value is optimized, so that the throughput of the relay search and the millimeter wave communication selected by using the strategy is optimal.
The invention has the beneficial effects that:
(1) the invention adds a new load factor in the system information of the candidate relay broadcast: a scheduling probability is desired. By incorporating the expected scheduling probability into the selection metric, the invention provides a strong access control method for the network, and obtains better network load balancing characteristic.
(2) The invention converts the performance of the relay searching and selecting scheme into a throughput optimization problem, and utilizes the optimal stopping theory to solve, thereby obtaining the optimal connection threshold value of the throughput. In combination with the connection threshold based on the optimal stopping theory, the relay search and selection scheme provided by the invention is optimal in throughput in millimeter wave relay selection.
(3) Because the threshold value and the connection strategy calculated by adopting the optimal stopping strategy are only relevant to the currently checked relay, the finally communication connection is not influenced by the previously checked relay any more, so that the method and the device avoid the condition that the synchronization of the UE and the previously relayed or extracted relay load information possibly becomes outdated due to factors such as time-varying radio environment, UE mobility, clock drift and the like, and the communication fails.
Drawings
FIG. 1 is a schematic diagram of a multi-relay millimeter wave communication system;
fig. 2 is a flow chart of relay search and selection based on maximum received power;
FIG. 3 is a schematic diagram of two-hop millimeter wave relay communication;
FIG. 4 is a relay search and selection flow diagram of the present invention;
fig. 5 is a schematic diagram of load distribution under different associations in a two-layer network, wherein (a) is a maximum received power association; (b) is the maximum signal-to-noise ratio correlation; (c) associating for the maximum selection metric;
fig. 6 is a schematic diagram showing comparison of throughput performance under different relay search and selection strategies.
Detailed Description
The invention is mainly applied to a 5G millimeter wave communication system. The application scenario is two-hop millimeter wave communication performed by two UEs through a relay. As shown in fig. 3, there are a large number of relays around the UE in which the two-hop mmwave relay communication is performed. The first hop between the source UE and the relay is millimeter wave communication, and relay search and selection are required before data communication of the source UE. The second hop between the relay and the sink UE is a reliable transmission. The present invention focuses on proper relay search and selection in the first hop.
The invention relates to a network element comprising: relays and Users (UEs). In the two-hop millimeter wave relay communication scheme of the 5G network, relays are used for signal transmission and signal reception, source users are used for signal transmission, and sink users are used for signal reception.
The invention designs a relay searching and selecting technology based on load perception and an optimal stopping theory. Expected scheduling probability beta of relay by the technology i As a load factor in the relay system information and is broadcast by the relay to the UEs. UE calculates connection threshold value mu by using optimal stopping theory, and calculates selection metric R by using load factor and relay SNR i 。
Fig. 4 shows a relay search and selection flow of the present invention. The method of the invention has the following scene parameters:
1. candidate relay periodic broadcast synchronization signal with period T syn And seconds. It is assumed that the UE learns the beamforming direction by detecting the synchronization signal of the relay broadcast. There may be L transmit-receive spatial signature pairs in the synchronization process.
2. The periodic broadcast of the candidate relay comprises the system information block of relay load information, and the period of the system information block is T sib And second. The relay load information is located in the first system information block. It is assumed that each UE can decode the system information block and extract the relay load information at once.
3. Suppose the number of active UEs served by Relay i is M i 。
4. Hypothesis randomThe access process requires a fixed time T ra And second. Suppose the data transmission duration of the source UE and the data communication relay is T data And second.
Relay searching and selecting step:
step 1.UE checks the relay i, in the beam forming scanning period LT syn After which time synchronization is obtained and the beam forming direction is determined. The UE then measures the corresponding SNR received from the relay.
Received SNR (expressed as SNR) if measured from Relay i i ) Below a certain threshold Γ, the UE stops checking the current relay i and starts checking another relay j.
If SNR i And F, entering the step 2.
Step 2, UE decodes the first system information block to extract the load information of relay i, namely the expected scheduling probability beta i ，β i ＝1/(M i +1)。
Step 3, UE calculates selection metric R of relay i i Wherein R is i ＝β i log(1+SNR i )。
Step 4, UE compares the selection metric R corresponding to the current search relay i i With a pre-calculated connection threshold mu.
If R is i And (5) the step is carried out, wherein the mu value is more than or equal to mu.
If R i <Mu, the UE selects another relay j, enters the step 1 and repeats the steps.
And 5, the UE completes relay search and selection and sends a random access lead code to the currently searched relay i to start a random access process. Thus, a connection is established between the UE and the selected relay, after which data communication may be scheduled.
The specific steps of the UE for pre-calculating the connection threshold value mu are as follows:
desired selection metric for hypothetical relays
As independent and identically distributed random variables
Having a cumulative distribution function of
The probability that each relay SNR does not fall below the threshold Γ is assumed to be the same and is Ρ (SNR ≧ Γ).
Step 2. iterative computation
Wherein
Iterating to converge, and taking the convergence value as the optimal throughput lambda * 。
Step 3, when the channel bandwidth is W, connecting the threshold value
The load balancing effect obtained by adding a load factor to the system information of the relay broadcast is shown in fig. 5. Figure 5 shows the implementation of load distribution under different association schemes in a two-tier network. In the network, there is one large relay and four micro relays, and a large number of UEs are uniformly distributed. Fig. 5(a), (b) are maximum received power association and maximum signal-to-noise ratio association, respectively, and it is clear that the network under the maximum selection metric association scheme has better load balancing compared to the serving UE distribution of each relay in the maximum selection metric association in fig. 5 (c). This is because the maximum metric association scheme takes into account the relay load factor in the relay search and selection process, and thus the scheme of the present invention is obviously effective.
Secondly, as shown in fig. 6, when the relay search and selection strategy of the maximum selection metric considers both the received power and the load and combines the proposed selection metric with the derived optimal stopping rule, the throughput performance is better than other relay search and selection strategies.
Claims (1)
1. A relay selection method in a millimeter wave communication system, the millimeter wave communication system comprising a source user, a plurality of relays and a sink user, wherein the relays are used for signal transmission and reception, the source user is used for signal transmission, and the sink user is used for signal reception; the method is characterized by comprising the following steps:
s1, source user detects the synchronization signal of ith relay broadcast, the synchronization signal includes relay load information, and SNR received from relay i is measured i If the value is greater than the set threshold value Γ, the process proceeds to step S2, otherwise, the j-th relay is selected, i ≠ j, i ═ j is updated, and the step S1 is repeated;
s2, the source user extracts the load information of the relay i from the synchronous signal to obtain the expected scheduling probability beta i ：
β i ＝1/(M i +1)
Wherein M is i Number of active users serving relay i;
s3, calculating selection metric R of relay i by source user i ：
R i ＝β i log(1+SNR i )
S4, judgment of R i If the current value is greater than or equal to the connection threshold value mu, if so, the step S5 is performed, otherwise, the source user selects the jth relay, i ≠ j, updates i ═ j, and returns to the step S1;
the calculation formula of the connection threshold value mu is as follows:
wherein, W is the channel bandwidth, and λ is the optimal throughput, and the calculation mode is as follows: setting an initial value lambda of optimal throughput * (0) K is any value greater than 0, iteratively:
t is the number of iterative calculation rounds, the initial value is 0, T ra Is randomThe access process requires a fixed time, T data Assuming desired selection metrics for relays for data transmission duration of source user and relay communication
As independent and identically distributed random variables
Having a cumulative distribution function of
The probability that each relay SNR does not fall below the threshold Γ is the same, and is p,
T syn for relaying the period of the broadcast synchronization signal, T sib The period of a system information block containing relay load information in a synchronization signal; after iteration till convergence, the convergence value is taken as the optimal throughput lambda * ；
And S5, selecting the relay i by the source user, and establishing connection between the source user and the sink user and the selected relay i to perform data communication.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103716853A (en) * | 2013-10-22 | 2014-04-09 | 南京邮电大学 | Self-adaption multiple-relay selection method in terminal through communication system |
| WO2018105158A1 (en) * | 2016-12-08 | 2018-06-14 | 日本電気株式会社 | Device and method for relay selection |
| CN110087199A (en) * | 2019-05-09 | 2019-08-02 | 信息产业电子第十一设计研究院科技工程股份有限公司 | The user group data service system and method for millimeter-wave systems downlink based on relaying |
| CN110832891A (en) * | 2017-06-26 | 2020-02-21 | 高通股份有限公司 | Techniques and apparatus for communication relay discovery |
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| KR102493536B1 (en) * | 2016-06-08 | 2023-01-31 | 삼성전자주식회사 | Relay communication method of a user equipment and the user equipment |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103716853A (en) * | 2013-10-22 | 2014-04-09 | 南京邮电大学 | Self-adaption multiple-relay selection method in terminal through communication system |
| WO2018105158A1 (en) * | 2016-12-08 | 2018-06-14 | 日本電気株式会社 | Device and method for relay selection |
| CN110832891A (en) * | 2017-06-26 | 2020-02-21 | 高通股份有限公司 | Techniques and apparatus for communication relay discovery |
| CN110087199A (en) * | 2019-05-09 | 2019-08-02 | 信息产业电子第十一设计研究院科技工程股份有限公司 | The user group data service system and method for millimeter-wave systems downlink based on relaying |
Non-Patent Citations (2)
| Title |
|---|
| Anindita Saha ; Farah Ashrafi ; Sadia Islam ; Risala Tasin Khan ; M..Relay selection and beamwidth adaptation to overcome blockage in mm-wave wireless private area network.《2016 International Workshop on Computational Intelligence (IWCI)》.2017, * |
| 基于NOMA的中继D2D通信系统容量分析和功率分配;柯春华;《硕士论文》;20191209;全文 * |
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