The story of an hour and the yellow wallpaper Introduction This is a contrast and compare essay of the two short stories story of an hour and the yellow wallpaper. This paper makes a comparison of the three literary devices that is symbolism, imagery, and the narrator. Symbolism literary devices use symbols and ideas to signify qualities and ideas. It gives a more profound meaning other than the one in literal sense. It shows an object that represents another, giving a deeper and more significant meaning. Imagery is a literary device use descriptive language to provide the reader with the imagination of the literature world and also adds symbolism; it majorly draws from the five senses, including sight, smell, taste, sound, and touch. Lastly, the narrator is the person telling a story, and majorly determines the story's point of view in fiction. Symbolism The narrator of the Yellow wallpaper had the sense that she had to interpret the wallpaper. The wallpaper symbolizes something that affects her directly. The wallpaper, therefore, has symbolism throughout the story. Initially, the wallpaper is not attractive since it is unclean yellow, ripped, and soiled. Worse still, the wallpaper has a formless pattern that attracts the narrator to try and understand how it is organized. After looking at the wallpaper for so long, she sees a sub-pattern with a ghost just behind the main pattern, but this was only visible in light. As she focuses on the strange pattern, the narrator notices a desperate woman whose stopping and crawling trying to escape from the main pattern, and this resembled the cage bars. The narrator sees the cage as a group of women heads, all strangled as they tried to escape. The wallpaper shows a family structure, tradition, and medicine where the narrator is trapped. The wallpaper is humble and domestic and uses this nightmare, wallpaper, as a symbol of domestic life where many women are trapped. Symbolism comes out well in the story of an hour. The heart trouble afflicting Louise is physical and symbolic. It represents Louise's uncertainty about lack of happiness and manages due to lack of freedom. Louise has heart trouble, which is the first thing she learned about her, and this is what announces Brently's death threatening. With her weak heart, she could not take such news well. Louise sees death as freedom, and her heart pumps blood faster. After her death, it could have been seen as if she had heart disease, and this could have been true since the shock of seeing Brently would kill her. Ironically, the doctor concludes that she dies of joy while it could be she dies due to lack of it. Louise may have died due to a broken heart due to the loss of her independence. The open window is symbolic, as well. It symbolizes the freedom that awaits Louise after the death of her husband. Louise sees the blue sky from the window with treetops and fluffy clouds (Chopin 253). From the window, she hears birds and people sing, and she also sme.

1. The story of an hour and the yellow wallpaper
Introduction
This is a contrast and compare essay of the two short stories
story of an hour and the yellow wallpaper. This paper makes a
comparison of the three literary devices that is symbolism,
imagery, and the narrator. Symbolism literary devices use
symbols and ideas to signify qualities and ideas. It gives a more
profound meaning other than the one in literal sense. It shows
an object that represents another, giving a deeper and more
significant meaning. Imagery is a literary device use descriptive
language to provide the reader with the imagination of the
literature world and also adds symbolism; it majorly draws from
the five senses, including sight, smell, taste, sound, and touch.
Lastly, the narrator is the person telling a story, and majorly
determines the story's point of view in fiction.
Symbolism
The narrator of the Yellow wallpaper had the sense that she had
to interpret the wallpaper. The wallpaper symbolizes something
that affects her directly. The wallpaper, therefore, has
symbolism throughout the story. Initially, the wallpaper is not
attractive since it is unclean yellow, ripped, and soiled. Worse
still, the wallpaper has a formless pattern that attracts the
narrator to try and understand how it is organized. After looking
at the wallpaper for so long, she sees a sub-pattern with a ghost
just behind the main pattern, but this was only visible in light.
As she focuses on the strange pattern, the narrator notices a
desperate woman whose stopping and crawling trying to escape
from the main pattern, and this resembled the cage bars. The
narrator sees the cage as a group of women heads, all strangled
as they tried to escape. The wallpaper shows a family structure,
tradition, and medicine where the narrator is trapped. The
wallpaper is humble and domestic and uses this nightmare,
wallpaper, as a symbol of domestic life where many women are

2. trapped. Symbolism comes out well in the story of an hour. The
heart trouble afflicting Louise is physical and symbolic. It
represents Louise's uncertainty about lack of happiness and
manages due to lack of freedom. Louise has heart trouble, which
is the first thing she learned about her, and this is what
announces Brently's death threatening. With her weak heart, she
could not take such news well. Louise sees death as freedom,
and her heart pumps blood faster. After her death, it could have
been seen as if she had heart disease, and this could have been
true since the shock of seeing Brently would kill her. Ironically,
the doctor concludes that she dies of joy while it could be she
dies due to lack of it. Louise may have died due to a broken
heart due to the loss of her independence. The open window is
symbolic, as well. It symbolizes the freedom that awaits Louise
after the death of her husband. Louise sees the blue sky from
the window with treetops and fluffy clouds (Chopin 253). From
the window, she hears birds and people sing, and she also
smells a rainstorm. All this symbolizes the joy of a new life.
When she contemplates the sky, she gets elated. She fully gets
excited and feels as if the window gives her life. This open
window enables a clear view at a distance. This symbolizes a
bright future with no obstacles. It is no coincidence that once
she moves away from the window, she loses her freedom.
Imagery
Imagery literature device is brought out clearly in both stories
to provoke senses and thoughts to enable the reader to have
imagination of what is being perceived to be occurring. The use
of diction makes the reader see what Mrs. Mallard sees when
looking out of the window as quoted, "I am sitting by the
window now, up in this atrocious nursery." ( Chopin 3). The
author brings out spring outside the window, and the day is
beautiful with a sweet smell that delays the rain. She also
describes a person singing a song, and Mrs. Mallard cannot hear
clearly, but it is refreshing. After being informed of her
husband's death, Mrs. Mallard would see the beauty outside
through the window. The reader gets a visual image when

3. Louise is looking out through the window as well as the
realization of her happiness with the death of her husband. The
realization of her freedom does not come immediately since, at
first, she feels confused. Instead of being happy, she is
sorrowful. At the very same time, her calm face sees the sky
with blue patched, and she becomes keen and bright, which is a
sign of happiness. This shows that she has conflicting emotions.
The reader can see these emotions as the author has elegantly
used imagery. The Yellow wallpaper also uses imagery to give
readers a clear picture of the story’s happenings. The author
describes the story giving details that helps the reader have the
picture in their mind. The narrator has prescribed the bed rest
due to what is thought to be hysteria, but in reality, it is most
probably postpartum depression. She is not allowed to have
physical stimulation, and only the details of her environment
are observed. At the start of the story, it is described as
"Flamboyant and the color revolting" (Gilman 793). Through
this, the narrator is able describe the home where the family has
a vacation in minute detail. How the narrator describes the
wallpaper makes the reader see. The narrator describes the
wallpaper to make them understand that the woman is well
educated and, therefore, keen on details. The wallpaper evokes
an emotional response to the woman, which is seen in her
statement, "It is dull enough to confuse the eye in following,
pronounced enough to irritate and provoke study constantly… "
(Gilman 793).
Narrator
The narrator in The Yellow Paper is the first person. The
narrator is also a paradox. The narrator starts to lose touch with
the world and gets to understand the inner reality of life. The
internal split is essential to understand the nature of her
suffering. At the point, she is faced with objects, relationships,
and situations that look natural and innocent, but in reality, it is
oppressive. In the plot of the story, the narrator attempts to
avoid accepting the extent to which her situation affects who
she is. The narrator is seen to be imaginative, and at a point, she

4. remembers when she was terrified by her imaginary nighttime in
her childhood (Gilman 259). In the story of an hour, the narrator
is a limited synonymous third person. The narrator stands
outside the characters and events described. The limited third
person is seen in the story where we are given the feelings and
thoughts of Louise; all the other characters are described
externally. Only bare facts are presented of the things that
affect Louse, such as the death of her husband. The narrator
says, "And yet she had loved him—sometimes. Often she had
not. What did it matter! What could love, the mystery, count for
in the face of this possession of self-assertion which she
suddenly recognized as the strongest impulse of her being!” the
narrator reports how Louise kept whispering to herself, “Free!
Body and soul free!" (Chopin 25). The limitations of the limited
third party are apparent in the above quote. As readers, we see
direct into Louise's mind with the exclamation marks denoting
that she is hard on herself to become free. The narrator of this
story is seen to be confined into a single character and,
therefore, unable to give much information about other
characters and other things.
References
Gilman, Charlotte Perkins. The yellow wallpaper. Project
Gutenberg, 1999.
Chopin, Kate. The story of an hour. Jimcin Recordings, 1981.
802.11 THROUGHPUT
comp40660 Assignment 1, February 2020
This assignment is worth 18% of the overall grade

5. Motivation
• Build a simple model of 802.11 frame exchange for TCP
and UDP, using OFDM of 802.11a and 802.11g
• The model will approximate the actual throughput of the
network
• RTS/CTS mechanism is enabled
• No contention
• Demonstration of the calculation for 802.11a – UDP case;
work on TCP case in lab.
• Assignment will be to modify for the .11g/n/ac/ax case for
both TCP and UDP.
802.11 Model
• Basic transactional model – 2 different transaction types,
namely
UDP and TCP.
• Any 802.11 transmission of data (from higher layer) requires
an

6. acknowledgement (ACK) by the .11 MAC.
• Each TCP / UDP packet is encapsulated in a single 802.11
frame.
Transport
Network
Data Link
Physical
Transport
Network
Data Link
PhysicalBits
Frame
Packet
Segment
802.11 Frame Exchange
UDP Case
• No guarantee of delivery
• Suitable for real-time applications such as VoIP, VoD

7. • UDP data encapsulated into 802.11 frame and
transmitted. Receiving station transmits 802.11 ACK.
Server Client
UDP
802.11 Frame Exchange
TCP Case
• Reliable delivery service guaranteeing that all bytes are
received and in correct order through TCP ACKs
• How is this different from the UDP case?
TCP
ACK
Server Client
Data Transmission
• 802.11 uses different inter-frame spaces:
• SIFS (Short Interframe Space)
• High-priority transmissions can begin once SIFS has elapsed

8. • ACK, RTS, CTS
• DIFS (DCF Interframe Space)
• Minimum idle time for contention-based services
• Stations can have access to the medium if it has been free for
a period longer than DIFS
Packet Headers
• 1500 bytes packet (TCP/UDP) is encapsulated:
• MAC header = 34 bytes
• SNAP LLC header = 8 bytes
• 3 bytes LLC (logical link control) header
• 5 bytes SNAP (sub-network access protocol) header
=> Total size = 1542 bytes
802.11a
• Amendment to the IEEE 802.11 specification
• 1999
• 5Ghz band

9. • Maximum data rate: 54 Mbps
• OFDM (Orthogonal Frequency Division Multiplexing)
• Available data rates: 54, 48, 36, 24, 18, 12, 9, 6 Mbps
802.11g
• 2003
• 2.4Ghz (same as 802.11b)
• Maximum data rate: 54 Mbps
• OFDM (copied from 802.11a)
• Available data rates: 54, 48, 36, 24, 18, 12, 9, 6 Mbps
802.11n
• 2009
• Both 2.4Ghz and 5Ghz
• Maximum data rate (20 MHz, 1 Spatial Streams): 72.2 Mbps
• Maximum optional data rate (40 MHz, 4 Spatial Streams):
600 Mbps
• OFDM with HT (High Throughput)

10. • Available data rates: 72.2, 65, 57.8, 43.3, 28.9, 21.7, 14.4,
7.2 Mbps
802.11ac
• 2013
• 5GHz band
• Maximum data rate (20MHz, 1 Spatial Stream): 96.3 Mbps
• Maximum wave 1 optional data rate (80MHz, 3 Spatial
Streams): 1300 Mbps
• Maximum wave 2 optional data rate (160MHz, 8 Spatial
Streams): 6933.6 Mbps
• OFDM with VHT (Very High Throughput)
• Available data rates: 96.3, 86.7, 72.2, 65, 57.8, 43.3, 28.9,
21.7, 14.4, 7.2 Mbps
802.11ax
• 2019
• Both 5Ghz and 2.4GHz band

11. • Maximum data rate (20MHz, 1 Spatial Stream): 143.4 Mbps
• Maximum data rate (160MHz, 8 Spatial Streams): 9607.8
Mbps
• Introduce Modulation and Coding Sets (MCS) with 1024-
QAM
• Available data rates: 143.4, 129.0, 114.7, 103.2, 86.0, 77.4,
68.8, 51.6, 34.4, 25.8, 17.2, 8.6 Mbps
Example Calculation - UDP
• Case: 802.11a @ 54Mbps
• A single data frame exchange:
1) Wait 1 DIFS
2) Send RTS
3) Wait 1 SIFS
4) Send CTS
5) Wait 1 SIFS
6) Transmit data
7) Wait 1 SIFS to send ACK
8) Send ACK

12. SIFS 16 μs
Slot Time 9 μs
DIFS=(2*Slot Time) + SIFS 34 μs
Example Calculation - UDP (cont.)
• Data is divided into symbols before transmission.
• Different amount of bits per symbol for each data rate
• See later slides of this set
• @54Mbps: 1 symbol encodes 216 bits
• Each symbol takes 4μs to transmit (11a/g only)
• Using OFDM each frame has 6 bits (tail) appended
=>232 μs to transmit the data frame
• RTS is a 20 byte long Control Frame and CTS is a 14 byte
+ 6)/216 = 1 symbol for
transmission for each frame.

13. Example Calculation – UDP (cont.)
• 802.11 ACK: 1 symbol (only 14 bytes) => 4 μs
• 20μs (Preamble) sync header is transmitted before each frame
DIFS + Preamble + RTS + SIFS + Preamble + CTS + SIFS +
Preamble +
Data + SIFS + Preamble + ACK =
34μs+ 20μs + 4μs +16μs + 20μs + 4μs + 16μs + 20μs + 232μs +
16μs +
20μs + 4μs = 406μs
So: time to send 1500 bytes (including IP and UDP headers) :
406 μs
Q: What is the throughput [Mbps] ?
In the practical: Do the same for TCP.
Assignment
• Calculate the actual throughput for 802.11a/g/n/ac/ax and for
all
available data rates, for both UDP and TCP.
• Your program should accept 3 arguments:
• Protocol (UDP/TCP)
• Standard (802.11a, 802.11g, 802.11n, 802.11ac_w1,

14. 802.11ac_w2,
802.11ax)
• Available data rate for each standard (e.g. 802.11a/g: 54, 48,
36,…)
• Note: For standard .11n/ac, consider SDur = 3.6�s only
• Your program must return for each scenario:
• The actual throughput [Mbps] in the normal case (20MHz and
1SS) AND the
best case:
• 40MHz/4SS for .11n
• 80MHz/3SS for .11ac_w1 ; 160MHz/8SS for .11ac_w2
• 160MHz/8SS for .11ax
• The amount of time needed to transfer 10 GB of data.
Assignment (cont.)
• Languages: C/C++, Java, Python
• Code must compile & run with no errors and be appropriately
commented throughout.
• A “Readme” file is required – detailing usage, and explaining:

15. • Why there is a difference between the actual throughput
and the advertised data rate.
• 802.11 performance improves after each release. Briefly
discuss the trade-offs involved in such improvements.
Assignment (cont.)
• Submission: Friday 28th February 2020, 23:59 sharp!!
• .zip file with source code + readme file
• Submit .zip through comp40660 page on CS Moodle
• This is an individual assignment: no group submissions
will be accepted and there should be no collaboration on
the assignment.
• Anti-plagiarism tools and techniques will be used to check
your submission.
Notes
• The differences between .11a and .11g that you have to take
into account:

16. • For 802.11g, SIFS = 10 μs
• Signal Extension appended to every 802.11g frame = 6 μs
• All other parameters, headers, tails etc. remain the same
as .11a
Notes (cont.)
• Specificities of .11n and .11ac/ax that you have to take into
account:
• 11n/ac MAC header = 40 bytes
• 802.11n/ac/ax SIFS = 16 μs
• Symbol duration of 802.11ax: 13.6μs
• Symbol duration of 802.11n/ac: 3.6μs (short symbol duration)
• The preamble in .11n is 46 μs (using 4 Spatial Streams)
• The preamble in .11ac_w1 is 56.8 μs (using 3 Spatial Streams)
• The preamble in .11ac_w2/ax is 92.8 μs (using 8 Spatial
Streams)
• All other parameters, headers, tails etc. remain the same as
.11a/g
Notes (cont.)

17. • 802.11n with 600 Mbps rate
• Maximum 4 Spatial Streams
• Maximum 40 MHz channels
• 802.11ac wave1 (802.11ac_w1) with 1300 Mbps rate
• Maximum 3 Spatial Streams
• Maximum 80 MHz channels
• 802.11ac wave2 (802.11ac_w2) with 6933.6 Mbps rate
• Maximum 8 Spatial Streams
• Maximum 160 MHz channels
• 802.11ax with 9608 Mbps rate
• Maximum 8 Spatial Streams
• Maximum 160 MHz channels
802.11a/g Encoding Block Sizes
• Symbol duration(SDur)
• Bits per symbol(NBits)
• Coding Rate (CRate)
• Number of sub-channels (NChan)
Data Rate = (1/SDur)*(NBits*CRate)*NChan
Data bits per OFDM symbol = NBits * CRate * NChan

18. Modulation NBits CRate NChan SDur (micro sec) Data Rate
(Mbps)
BPSK 1 1/2 48 4 6
BPSK 1 3/4 48 4 9
QPSK 2 1/2 48 4 12
QPSK 2 3/4 48 4 18
16-QAM 4 1/2 48 4 24
16-QAM 4 3/4 48 4 36
64-QAM 6 2/3 48 4 48
64-QAM 6 3/4 48 4 54
11a/11g Data Rates
802.11n/ac Encoding Block Sizes
Modulation NBits CRate NChan
Data Rate (Mbps)
SDur=4us
Data Rate (Mbps)
SDur=3.6us
BPSK 1 1/2 52 6.5 7.2

19. QPSK 2 1/2 52 13 14.4
QPSK 2 3/4 52 19.5 21.7
16-QAM 4 1/2 52 26 28.9
16-QAM 4 3/4 52 39 43.3
64-QAM 6 2/3 52 52 57.8
64-QAM 6 3/4 52 58.5 65
64-QAM 6 5/6 52 65 72.2
256-QAM
(11ac)
8 3/4 52 78 86.7
256-QAM
(11ac)
8 5/6 52 86.7
96.3
11n and 11ac Data Rates (20 MHz, 1 SS)
802.11n/ac supports both Symbol duration 4�s (for back
compatibility with 802.11a/g)
and 3.6�s (short symbol duration) – you should ONLY consider
SDur = 3.6�s

20. 802.11n/ac Maximum Data Rates
• Number of Spatial Streams (Nss): matching number of
antenna pairs at the
sender and the receiver ends
Channel Width NBits CRate NChan
Data Rate (Mbps)
SDur=3.6us (Nss=1)
11n Max Rate
(Nss=4)
20 Mhz 6 5/6 52 72.2 288.8
40 Mhz 6 5/6 108 150 600
11n Max Data Rates
Channel Width NBits CRate NChan
Data Rate (Mbps)
SDur=3.6us (Nss=1)
11ac Max Rate
(Nss=8)
20 Mhz 8 5/6 52 96.3 770.4
40 Mhz 8 5/6 108 200 1600
80 Mhz 8 5/6 234 433.3 3466.4

21. 160 Mhz 8 5/6 468 866.7 6933.6
11ac Max Data Rates
802.11ax Maximum Data rates
• 01 Spatial Stream (Nss):
20MHz
Modulation NBits CRate NChan
Symbol
duration (us)
Data Rate
(Mbps)
BPSK 1 1/2 234 13.6 8.6
QPSK 2 1/2 234 13.6 17.2
QPSK 2 3/4 234 13.6 25.8
16-QAM 4 1/2 234 13.6 34.4
16-QAM 4 3/4 234 13.6 51.6
64-QAM 6 2/3 234 13.6 68.8
64-QAM 6 3/4 234 13.6 77.4
64-QAM 6 5/6 234 13.6 86.0

22. 256-QAM 8 3/4 234 13.6 103.2
256-QAM 8 5/6 234 13.6 114.7
1024-QAM 10 3/4 234 13.6 129
1024-QAM 10 5/6 234 13.6 143.4
802.11ax Maximum Data rates
• 08 Spatial Streams (Nss):
160MHz
Modulation NBits CRate NChan
Symbol
duration (us)
Data Rate
(Mbps)
BPSK 1 1/2 1960 13.6 576.5
QPSK 2 1/2 1960 13.6 1152.9
QPSK 2 3/4 1960 13.6 1729.4
16-QAM 4 1/2 1960 13.6 2305.9
16-QAM 4 3/4 1960 13.6 3458.8
64-QAM 6 2/3 1960 13.6 4611.8

23. 64-QAM 6 3/4 1960 13.6 5188.2
64-QAM 6 5/6 1960 13.6 5764.7
256-QAM 8 3/4 1960 13.6 6917.6
256-QAM 8 5/6 1960 13.6 7686.3
1024-QAM 10 3/4 1960 13.6 8647.1
1024-QAM 10 5/6 1960 13.6 9607.8
TCP ACK – Packet and Header
• TCP ACK – 40 bytes of TCP/IP header info. No ”real” data
contained
within the ACK. The TCP header will contain all that is
required to
acknowledge the previous TCP packet/segment.
• As before in the case of 802.11a/g, we add 42 bytes for the
802.11
MAC header (34 bytes and SNAP header encapsulation 8 bytes)
to the
TCP ACK packet, as this appears as ”just data” to 802.11
• In the case of 802.11n/ac/ax, we add 48 bytes for the 802.11
MAC
header (40 bytes and SNAP header encapsulation 8 bytes) to the
TCP
ACK packet.

24. 802.11 Frame Exchange – TCP
Example calculation (Data bits per OFDM symbol)
• User input: UDP, 43.3Mbps, 802.11ac_w2
channels
• For a data rate of 43
= 468
(160MHz)
• Number of bits per symbol = (NBits * CRate * NChan) * Nss
= (4 * ¾ *
468) * 8 = 11232 bits/symbol