Network efficiency enhancement by reactive channel state based allocation scheme

International Journal of Electrical and Computer Engineering (IJECE)
Vol. 10, No. 3, June 2020, pp. 3275~3283
ISSN: 2088-8708, DOI: 10.11591/ijece.v10i3.pp3275-3283  3275
Journal homepage: http://ijece.iaescore.com/index.php/IJECE
Network efficiency enhancement by reactive channel state based
allocation scheme
Umesha G. B., M. N. Shanmukha Swamy
Department of Electronics and Communication Engineering,
Sri Jayachamarajendra College of Engineering (SJCE), India
Article Info ABSTRACT
Article history:
Received Apr 10, 2019
Revised Dec 11, 2019
Accepted Jan 8, 2020
Now a day the large MIMO has considered as the efficient approach to
improve the spectral and energy efficiency at WMN. However, the PC is
a big issue that caused by reusing similar pilot sequence at cells, which also
restrict the performance of massive MIMO network. Here, we give
the alternative answer, where each of UEs required allotting a channel
sequences before passing the payload data, so as to avoid the channel
collision of inter-cell. Our proposed protocol will ready to determine
the channel collisions in distributed and scalable process, however giving
unique properties of the large MIMO channels. Here we have proposed
a RCSA (Reactive channel state based allocation) scheme, which will very
productively work with the RAP blockers at large network of MIMO.
The position of time-frequency of RAP blocks is modified in the middle of
the adjacent cells, because of this design decision the RAP defend from
the hardest types of interference at inter-cell. Further, to validate
the performance of our proposed scheme it will be compared with other
existing technique.
Keywords:
Base stations (BSs)
Multiple-in multiple-out
(MIMO)
Pilot contamination (PC)
Random access protocol (RAP)
User equipment’s (UEs)
Copyright © 2020 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Umesha G. B.,
Department of Electronics and Communication Engineering,
Sri Jayachamarajendra College of Engineering (SJCE),
Mysore, Karnataka, India.
Email: umesh2719@rediffmail.com
1. INTRODUCTION
Massive MIMO is a technology where cellular BSs are having large number of antennas (NoA).
It shows significantly amount of improvement in reliability and capacity of the wireless system, also it allows
improve orders of magnitude in the spectral. The energy efficiency is also can be provided through relatively
simple processing in massive MIMO (mMIMO), therefore it has been broadly studied from last two decades,
also considered at many wireless standards. As per the random matrix theory [1], the channel vectors in
between the BS and UE become the pairwise orthogonal. Therefore, it results the minimization of small-scale
fading and uncorrelated noise effect as per the increment of antennas at BS in the MIMO network.
Subsequently, the essential transmitted energy as per bit also can be asymptotically less without of much
performance loss [2].
There are several contributions which provide insights on the energy efficient design of system;
in [3], provided the optimization at downlink side of massive MIMO system using zero-forcing pre-coding
scheme. Iterative prototype was considered under a true power consumption system in order to increase
the energy efficiency. Though the approach aimed to get the enhanced energy efficiency at uniform rates for
the every user, with considering the suitable channel state information. Moreover, a resource allocation based
approach has provided in [4] to obtain the optimal energy efficiency with the BS coordination, the outcome
reflected that the energy efficiency optimization difficulty was not convex but it was able to transform into

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Int J Elec & Comp Eng, Vol. 10, No. 3, June 2020 : 3275 - 3283
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the convex fractional programming. However, the author in [5], aimed towards the theoretical investigation
of energy efficiency and spectral efficiency for the multi-user type massive MIMO system. It showed some
visions on the way for antennas allocation, also derived nearly expressions for the number of users that are
necessary to be served in a network. However, it did not able to provide the complete structure and therefore
the considered model was not much practical to use further.
Through the comparison with traditional system of MIMO [6] as shown in Figure 1, the large
MIMO has many benefits such as the processing of modest linear at BS and also the antennas usage at
mobile terminal. While considering the Time DD (division duplex) at large network of MIMO,
the symmetrical pilots have some resources and need to utilize in adjacent cellular space, wherever
the channel utilize offers grow for the channel contamination. That causes the negative impact, for example,
attainable rate execution and exactness estimation at the uplink channel [1]. The author in [7] have thought
about the CR-MIMO (cognitive radio), wherever the interference is occurred because of the optimal users of
data transmission and therefore the essential users have affected through the channel transmission. In [8],
the essential users promises the QoS in large system of MIMO through learning the impact of vast-scale
essential BS on few optimal network of MIMO and through setting the best interference level in large
network of MIMO. In [9], a pilot scheme for large MIMO of cognitive network has been proposed to
improve the quality of channel evaluation of optimal users with reducing the negative reaction on essential
network of channel estimation. In [10], propose a reciprocity which is based on large MIMO of beam-forcing
method, so as the UEs (user equipment) during a network. Whereas a full spatial range sharing at large
MIMO of network has been proposed [11] with the minimized overhead of preparing to reduce the PC.
Likewise it utilizes 2-D DFT (Discrete Fourier Transform) for angular directional and spread of
arrival estimation.
Figure 1. MIMO network diagram
Usually the cellular network assigns the dedicated resources to individual active of UE, in this
manner it is vital for the BS to transmit time-frequency of resources area. The large network of MIMO
allocates all assets of time-frequency to all UEs and confines them spatially in understanding to their channel
sequences. There are restricted numbers of channel because of rational block size, while the concept of large
MIMO [12], the important channel use again over the cellular area and it causes the channel contamination of
inter cell, which leads toward the extra interference [13]. Thinking about the crowded urban situations,
the number of active and inactive UEs present in the CN (cellular network) which is significantly more than
the all accessible channel carrier groupings. In this way the channel can’t be determined for all time with
the specific UE in cell, because of this present it is needed to be deviously allocated and de-allocated so as to
pursue its unpredictable recurrent information traffic design. The RAP (random access protocol) can be
the best decision for this sort of channel resources allocation; however the design is additionally expected to
beat the collision in dense cells immediately. In [9], proposed a technique where the UEs can ready to
transmit the information under a chosen random channel from the normal pool, this reduces the entrance
delays at the cost of channel collision that causes the intra-cell PC.
The collision is introduced because the graph code in [14] and also the belief propagation is taken
into account to moderate the PC through applying the principle of RAC (random access code). The many SE
(spectral efficiency) expressions are considered in [15] and utilized to enhance the probability of UE
activation and also the channel length. Also, the asynchronous of timing UE is specified in [9] so as to
determine and detect the channel collision in RAP. During this paper, we give the alternative answer, where

Int J Elec & Comp Eng ISSN: 2088-8708 
Network Efficiency enhancement by reactive channel state based allocation scheme (Umesha G. B.)
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every of UEs required allotting a channel sequences before passing the payload data, so as to avoid
the channel collision of intra-cell. These represent the thought about scenario of payload transmission within
the large MIMO network [12-13]. Here, we have got targeted on the urban organizations with the help of few
initial variation of the timing and propose a RAP for UEs that need to get the cellular network. Our proposed
protocol will ready to determine the channel collisions in distributed and scalable process, however giving
unique properties of the large MIMO channels. Here we have contributed a RCSA (Reactive channel state
based allocation) scheme, which will very productively work the RAP blockers at large network of MIMO.
The position of time-frequency of RAP blocks is modified in the middle of the adjacent cells, because of this
design decision the RAP defend from the hardest types of interference at inter-cell.
2. LITERATURE SURVEY
A mMIMO is one of the most well-known technologies for the wireless communication and
attracted the huge number of researchers due to its vast spatial diversity and high data transmission
rate [16, 17]. However, in mMIMO system, the PC is a big issue that caused by reusing similar pilot
sequence at cells, which also restrict the performance of network and cannot be reduced through maximizing
the NoA [1]. Pilot or channel allocation is the effective process to minimize the PC [18-20]. In paper [21],
proposed a pilot sequence based allocation approach in order to mitigate the consequence of PC in massive
MIMO system; firstly derived the sum rate of uplink system when the BS antennas tend to infinity.
In accordance to the derived expression, the contamination of pilot is only impairment with respect to
the system performance. Afterwards, provided an optimized model of pilot allocation in order to increase
the system sum-rate, where the outcome is obtained through all the conceivable allocations required to be
examined that leads towards the higher computational complexity.
In paper [22], proposed the asynchronous scheduling approach that based upon the fractional reuse
of pilot reuse, which allows the users to be free from PC at the time of uplink transmission. In according to
the interference level, two groups are created from the users that can be denoted as center users, who’s
having the minor PC; also the edge users, who’s having the simple PC and based upon this difference, a cell-
centric pilot set can be reused for entire center users in cells; whereas, a set of cell-edge (CE) pilot is
considered for the edge users under the adjacent cells. Therefore, the used pilots through the CE users are
independent to each other, so the edge users able to transmit pilots at any period of time; nonetheless, the set
of pilot for center users can be reused for entire cells, where the cell center users transmit their pilots over
the non-overlapped times to evade PC.
A fair pilot allocation method has proposed in [23] for the multi-cell mMIMO, to reduce the PC
effect and increase the sum rate (SR) of system with assuring the services among the users. Min Leakage
algorithm (MLA) that is a heuristic algorithm is proposed to resolve the problem of optimization with lower
system complexity, while considering the MLA can only deliver a suboptimal performance. Moreover,
a greedy pilot allocation based User-Exchange approach is proposed to further improve the system SR and
the services among users [23]. In [24], author considered the problem of resource allocation for the uplink
mMIMO system, where the antennas at BS are priced and the virtualization has done across the service
providers; though the mobile network provider (MNP) holds the complete infrastructure of antennas decides
the price, also the Stackelberg game is considered for the maximization of net profit of MNP, whereas
the minimum SR necessities of service providers are fulfilled. In order to resolve the bi-level problem of
MNP, initially provided the closed-form optimal responses of service providers with respect of MNP pricing
strategies. Therefore, the MNP problem can be decrease towards the single level optimization process.
Afterwards, the approximations and transformations are used to cast the MNPs difficulty with the integer
constraints to Signomial geometric program and, then applied an iterative approach based upon successive
convex estimation in order to resolve Signomial geometric program.
Energy efficient based resource allocation approach is proposed in [25] for the multi-users mMIMO
systems with the amplify-and-forward relay, where the dedicated relay guides the pairwise information
interchange at several parts of single antenna UE. The energy efficiency system has theoretically examined
through considering random matrix theory and huge system analysis, this results the optimal approximation
for MIMO system with reasonable NoA. It also provides the some efficient approaches with different type of
channel state information in order to increase the system energy efficiency through scheduling
the appropriate relay antennas and, UE pairs with their corresponding transmission power. With respect to
the conventional resource allocation approaches, the proposed prototype avoids the calculations of
complicated matrix and the instant channel state information of the small-scale fading; so it provides efficient
computation with small overhead of channel state information. Mostly of the works aimed on maximizing
sum-rate of UEs but they have not considered the delay time that can decrease the all system performance for
massive MIMO system.

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3. PROPOSED METHODOLOGY
Here, we have considered the major four steps of RCSA approach as shown in Figure 2, where,
the base station (BS) transmit the control signal and each of the UE will take use of this signal to predict its
channel gain average and synchronizes itself through the BS. Afterwards, under a system initialization
process and querying step, an inactive subset of UEs is considered in cell that wants to active. Each of
the UE selects sequences of channel at random state from the predefined RAP channel pool, so the BS
an estimates its channel that has to be transmitted over. The UEs selection is similar for the RAP channels,
if the collision has taken place then the BS acquires a superposition UE estimation channels. Afterwards,
the BS cannot able to identify the followed collisions that similar to the situation in LTE.
Figure 2. A proposed RCSA scheme for massive MIMO
Therefore, in reaction of queuing the BS responses through sending the downlink channels that are
pre-coded through the channel estimates, which results at spatially aimed signals toward the UEs and offer
the suitable RAP resource. In step 3, channel state analysis and resource contention mechanism is considered,
where the probability of non-colliding channel transmission is considerably increased in RCSA approach.
That allows the massive MIMO system to acknowledge UEs under the crowded scenarios, also provide
the identity of UE and payload transmission request, which help to resemble the radio resource control
connection followed by the demand in LTE. Whereas considering the step 4, it allows these resources by
assigning a pilot sequence that further can be used at the payload blocks or to starts conflict resolution at
the few cases whenever RAP collisions occurred. Therefore, the proposed RCSA approach stands for both;
on its own, also for the orthodox contention resolution methods.
Each of 𝐵0 UEs selects one of the uniformly pilots 𝑔 𝑘 at random under a RA block, 𝑏 UE chooses
the pilot 𝑐(𝐵) ∈ {1,2, . . . . , 𝑔 𝑘}. Moreover, UE generally like to be active at the present block with
the probability of 𝐾𝑥 ≤ 1, which is permanent scenario based parameter that shows how the UE transmit or
receive the data packets. Therefore, each of the inactive UE transmits a specific pilot sequence 𝜓 𝑡 with
the 𝐾𝑥 𝑔 𝑘⁄ probability. The set is given be 𝑄𝑡 that consist the UEs indices that transmit t pilot, and
𝜓 𝑡 transmit sequences has a binomial distribution.
𝑄𝑡 = {𝑏: 𝑐(𝑏) = 𝑡, ℎ 𝑏 > 0} (1)
|𝑄𝑡|~𝛿(𝐵0, 𝐾𝑥 𝑔 𝑘⁄ ) (2)
Where, 𝛿 is denotes the circularly-symmetric composite Gaussian distribution. We considered that the 𝑡 pilot
is not in used (|𝑄𝑡| = 0) with the probability (1 − 𝐾𝑥 𝑔 𝑘⁄ ) 𝐵0 and choose only one UE that is (|𝑄𝑡| = 1) with
the 𝐵0 𝐾𝑥 𝑔 𝑘⁄ (1 − 𝐾𝑥 𝑔 𝑘⁄ ) 𝐵0−1
probability. Therefore, the collision of RA (|𝑄𝑡| ≥ 2) occurs during at
arbitrary pilot with the probability of;
1 − (1 − 𝐾𝑥 𝑔 𝑘⁄ ) 𝐵0 − 𝐵0 𝐾𝑥 𝑔 𝑘⁄ (1 − 𝐾𝑥 𝑔 𝑘⁄ ) 𝐵0−1
(3)

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In a massive MIMO network [26], the collisions are needed to recognize and resolve as before of
UE entering at payload blocks. Our proposed approach is a distributed process in order to resolve
the collisions at UEs by utilizing the massive MIMO principle. Where the channel vectors at UE can be
represented as 𝑏 ∈ 𝐵0 and the BS can be given as 𝑑 𝑏 ∈ C 𝐸
, where we consider a very general propagation
model and the channels are also can be pre-assumed to satisfy these two conditions:
‖d 𝑏‖2
𝐸
𝐸→∞
→ 𝛽𝑏, ∀𝑏, (4)
d 𝑏
D
d 𝑎
𝐸
𝐸→∞
→ 0, ∀𝑏, 𝑎, 𝑏 ≠ 𝑎, (5)
For some strictly value of 𝛽𝑏 that is known to 𝑏 UE, thus the channels can offered the asymptotic
favorable propagation and channel reinforcing [27]. While considering step 1 for the RAP, the signal
received through the BS is 𝐅 ∈ C 𝐸×𝑔 𝑘 from pilot transmission can be given as:
𝐅 = ∑ √ℎ𝑏𝑏∈𝐵0
d 𝑏 𝜓 𝑐(𝑏)
T
+ 𝐋 + 𝐌 (6)
where, inter-cell interference is symbolized through the 𝐋, 𝐌 ∈ C 𝑀×𝜏 𝑝 is the self-determining receiver noise
and individual distribution of element can be given as 𝐶𝑍(0, 𝜎2) that is a complex Gaussian distribution,
where the matrix C 𝐸×𝑔 𝑘 defines the interferences from the different adjacent cells. The time-frequency
properties are divided into the coherence blocks of T channel and 𝐸 that represents NoA. Transmit power is
represented by ℎ, C shows the complex value and transmitted pilot is represented by 𝜓. Through, correlating
F with a normalized 𝜓 𝑡 pilot sequence, the BS obtains as;
f𝒕 = 𝐅
𝜓 𝑡
∗
‖𝜓 𝑡‖
= ∑ √ℎ 𝑎‖𝜓 𝑡‖d 𝑎𝑎=𝑄𝑡
+ 𝐋
𝜓 𝑡
∗
‖𝜓 𝑡‖
+ 𝜑 𝑡 (7)
f𝒕 = ∑ √ℎ 𝑎 𝑔 𝑘d 𝑎𝑎=𝑄𝑡
+ 𝐋
𝜓 𝑡
∗
‖𝜓 𝑡‖
+ 𝜑 𝑡 (8)
where, ‖𝜓 𝑡‖ is equal to√ 𝑔 𝑘, 𝜑 𝑡 is the current receiver noise and it can be given as;
𝜑 𝑡 = 𝑀
𝜓 𝑡
∗
‖𝜓 𝑡‖
~𝐶𝑍(0, 𝜎2
𝛝 𝐸) (9)
where, 𝛝 𝐸 denotes the 𝐸 × 𝐸 identity matrix. Recall that the 𝑄𝑡 is a UEs set which transmitted through
𝜓 𝑡 pilot and, the interference L at inter-cell can be given as;
𝐋 = ∑ L 𝜚κ 𝜚
T
𝜚 + ∑ ∑ √ℎ 𝑡,𝑏Υ𝑡, 𝑏, 𝜓 𝑡
T
𝑏∈𝑄𝑡
𝑖𝑛𝑡𝑒𝑟
𝑔 𝑘
𝑡=1 (10)
The first summation in above (10) shows the 𝜚 interfering transmission of data that carried out at
neighboring cells, where, κ shows random data sequence and Υ𝑡 is the channel to the BS. In response queuing
step, the BS replies towards the RAP pilots by sending the pre-coded downlink signal, which corresponds to
each RAP pilots that were being used at the uplink. The reaction towards 𝜓 𝑡 is the sequence of channel 𝑁𝑡 ∈
C 𝑔 𝑘 and, the downlink channel sequences can be presented as 𝑁1, 𝑁2, . . . , 𝑁𝑔 𝑘
∈ C 𝑔 𝑘 that are orthogonal to each
other and satisfy the condition ‖𝑁𝑡‖2
= 𝑔 𝑘. If the BS consider the normalized conjugate then
𝑝 𝑡
∗
‖𝑝 𝑡‖
as a pre-
coded vector at 𝑁𝑡 pilot sequence in downlink. Then after the signal directed to the multi-cast maximum ratio
of transmission at UEs in 𝑄𝑡, so the complete pre-coded downlink pilot signal 𝐑 can be given as;
𝐑 = √ 𝑠 ∑
𝑝 𝑡
∗
‖𝑝 𝑡‖
𝑔 𝑘
𝑡=1 𝑁𝑡
T
(11)
where, the downlink transmits 𝑠 power and has a pre-defined value, whereas the pilot channel length is given
as 𝑔 𝑘 and it is independent from the NoA. The received signal 𝐔 𝑏 ∈ C 𝑔 𝑘 at the UE 𝑏 ∈ 𝑄𝑡 is;
𝐔 𝑏
T
= d 𝑏
T
𝐑 + 𝑟𝑏
T
+ 𝜂 𝑏
T
(12)
where, h 𝑘
T
shows the reciprocal downlink channel, 𝑣 𝑘 corresponds to C 𝑔 𝑘 is an inter-cell interference, 𝜂 𝑏 is
a receiver noise signal. Through correlating the 𝐔 𝑏 receiver signal with the normalized downlink 𝑁𝑡 pilot
sequence, the UE obtain as;

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𝑈 𝑏 = 𝐔 𝑏
T 𝑁𝑡
∗
‖𝑁𝑡‖
= √ 𝑠𝑔 𝑘d 𝑏
T
+ 𝑟𝑏
T 𝑁𝑡
∗
‖𝑁𝑡‖
+ 𝜂 𝑏 (13)
where, the effective receiver noise 𝜂 𝑏 = 𝜂 𝑏
T 𝑁𝑡
∗
‖𝑁𝑡‖
~𝐶𝑍(0, 𝜎2), therefore the asymptotic favorable propagation
is considered.
𝑈 𝒃
√𝐸
⁄ = √ 𝑠𝑔 𝑘
(d 𝑏
T
𝑝 𝑡)
∗
𝐸
1
√
1
𝐸
‖𝑝 𝑡‖2
+ 𝑟𝑏
T 𝑁𝑡
∗
√𝐸‖𝑁𝑡‖
+
𝜂 𝑏
√𝐸
(14)
𝐸→∞
→
√ℎ 𝑏 𝑠𝛽𝑏 𝑔 𝑘
√∑ ℎ 𝑎 𝛽 𝒂 𝑔 𝑘 + 𝜔 𝑡 + 𝜎2
𝑎=𝑄𝑡
The noise does not maximize with 𝐸, so the 𝑟𝑏 inter-cell interference is not affected by 𝐸. Later on
the assumption is made if the nearest interfering cells transmit RA pilots through assign downlink pilots in
different methods, which causes the minimization at pilot contaminated interference. Considering (14),
we can define the sum of interference gain and signal received at BS at uplink transmission of 𝜓 𝑡 pilot;
𝑉𝑡 = ∑ ℎ 𝑎 𝛽 𝒂 𝑔 𝑘 + 𝜔 𝑡𝑎=𝑄𝑡
(15)
So, the function 𝑅(. ) provides the real block of its input and based on the (14), the approximation
can be given as;
𝑅(𝑈 𝒃)
√𝐸
≈
√ℎ 𝑏 𝑠𝛽 𝒃 𝑔 𝑘
√𝑉𝑡+𝜎2
(16)
where, we have removed the imaginary part of 𝑈𝑏, which contains the estimation error, interference and
noise. Therefore, the b UE can use the approximation in order to estimate 𝑉𝑡;
𝑉̂
𝑡,𝑏
𝑎𝑝𝑝𝑟𝑜𝑥
= max (
𝐸𝑠ℎ 𝑏 𝛽 𝑏
2
𝑔 𝑘
2
(𝑅(𝑈 𝑏))2
− 𝜎2
, ℎ 𝑏 𝛽 𝒃 𝑔 𝑘) (17)
where, max function will take maximum of two values and this estimator become asymptotically error-free
when 𝐸 → ∞ (14).
In step 3 provide the channel state analysis and resource contention mechanism to resolve
the channel contentions issue at the distribute manner, therefore each channel is repeated ones at one UE.
UE 𝑏 ∈ 𝑄𝑡 is taken for the signal gain ℎ 𝑏 𝛽𝑏 𝑔 𝑘 and, estimate 𝑉̂𝑡,𝑏 signal gain sum that contending UEs and
inter-cell interference. The BS takes the RAP repetitive pilot transmission that followed by uplink message,
BS takes the 𝑡 𝑡ℎ
pilot signal to predict the channel at UEs, which sent the 𝜓𝑡
and decodes the corresponds
message. Afterwards the successful decoding, the BS acknowledged one UEs in 𝑄𝑡 to provide coherent
blocks of payload by allocating the pilot channel sequence. This allocation result is forwarded towards
the downlink in step 4 and same for the step 2. The RCSA approach is repeated for the fixed number of
interval, if the UEs were not recognised in step 4, then it’s instructed to transmit via a new RAP channels.
4. RESULTS AND ANALYSIS
Here, we provide result analysis using our proposed RCSA approach that compared with the vertex
graph-coloring-based pilot assignment (VGCPA) approach [28]. The proposed scheme exhibits the four
major steps; system initialization and querying, response queuing, channel state analysis and resource
contention, and resource allocation, which allows decreasing the delay time and failed access attempts, also
increases the end-to-end success rate. In order to validate the result analysis two scenarios has been
considered, where all the other parameters are same except the number of BS. The parameters are shown in
Table 1, which has been applied before simulation of code. Here we will compute the three major things that
cause the PC in a network such as; end-to-end success rate, delay time in mille seconds and failed
access attempts.
In scenario A, we computed end-to-end success rate, delay time in mille seconds and failed access
attempts at 100 number of BS. Figure 3 shows end-to-end success rate, where our proposed model got
72.83% of improvement with respect to VGCPA. Figure 4 shows delay time in msec, where our proposed
model got 43.63% less average delay time with respect to VGCPA. Figure 5 shows the failed access
attempts, where the mean failed access attempts from our RCSA scheme is 0.0844, whereas from VGCPA

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we got 0.75. Similarly coming to scenario-B, where the considered number of BS is 200. Figure 6 shows end-
to-end success rate, where our proposed model got 73.38% of improvement compared to VGCPA model.
Figure 7 shows delay time, where our proposed model got 43.68% less average delay time compared to
VGCPA. Figure 8 shows the failed access attempts, where the mean failed access attempt from our RCSA
scheme is 0.0855, which is 88% less compared to existing VGCPA approach.
Table 1. System parameters
Serial No. Parameters Parameters Values
1 Monte-Carlo realizations 500
2 BS antennas 100 or 200
3 Number of UEs 1000 to 20000
4 Maximum number of attempts 10
5 Probability of retransmitting 0.5
6 RA pilot signals 10
7 Transmit power of UEs 1 dB
8 Transmit power of the BS 1 dB
9 Noise variance 1 dB
10 Standard deviation of fading 10 dB
11 Cell Radius 250 m
12 Number of active UEs in neighboring cells 10
Scenario-A
Figure 3. End-to-end success rate Figure 4. Delay time (ms)
Figure 5. Failed access attempts

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Scenario-B
Figure 6. End-to-end success rate Figure 7. Delay time (ms)
Figure 8. Failed access attempts
5. CONCLUSION
In massive MIMO system, the PC is a big issue that caused by reusing similar pilot sequence at
cells. The proposed scheme exhibits the four major steps, which allows decreasing the delay time and failed
access attempts, also increases the end-to-end success rate. In reaction of queuing the BS responses through
sending the downlink channels that are pre-coded through the channel estimates, which results at spatially
aimed signals toward the UEs and offer the suitable RAP resource. The channel state analysis and resource
contention mechanism is considered for the non-colliding channel transmission is considerably increased in
massive MIMO network. So RCSA approach also allows the massive MIMO system to acknowledge UEs
under the crowded scenarios. In the result analysis section our proposed RCSA approach is compared with
the VGCPA approach, and we showed that our proposed model has performed considerably well at both
considered scenario which validate the performance of our model.
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