Data And Computer Communications 10th Edition William Stallings - Solutions

Briefly define MIMO and MU-MIMO.
Using the same assumptions that are used for Figure 16.11, plot line utilization as a function of P, the probability that a single frame is in error for the following errorcontrol techniques:a. Stop-and-waitb. Go-back-N with W = 7c. Go-back-N with W = 127d. Selective reject with W = 7e. Selective
Consider the use of 1000-bit frames on a 1-Mbps satellite channel with a 270-ms delay. What is the maximum link utilization fora. Stop-and-wait flow control?b. Continuous flow control with a window size of 7?c. Continuous flow control with a window size of 127?d. Continuous flow control with a
A channel has a data rate of 4 kbps and a propagation delay of 20 ms. For what range of frame sizes does stop-and-wait give an efficiency of at least 50%?
A LDPC code is defined by the parity-check matrix h = D 1 1 0 1 0 0 0 1 1 0 1 0 1 0 0 0 1 1 0 0 1 1 0 1 TThe valid codeword 001011 is transmitted and the invalid codeword 101011 is received. Using the message-passing algorithm of Section 16.2, show the procedure for correcting the error.
Draw the Tanner graphs for each of the LDPC codes in Figure 16.6.
A (6, 3) parity-check code is defined by the parity-check matrix h = C 1 0 1 1 0 0 1 1 0 0 1 0 0 1 1 0 0 1 Sa. Determine the generator matrix G.b. Find the codeword that begins 101.
A (6, 3) parity-check code is defined by the following equations:c1 c3 c4 = 0 c1 c2 c3 c5 = 0 c1 c2 c6 = 0a. Determine the parity-check matrix H.b. Determine the generator matrix G.c. List all valid codewords.
A simple FEC code transmits every data bit 5 times. The receiver decides on the value of each data bit by choosing majority vote. If the uncoded bit error probability is 10-3, what is the coded bit error probability?
For the example related to Table 16.1:a. Draw the LFSR.b. Using a layout similar to Figure 6.6b, show that the check bits for the data block 1010 are 001.
Divide f(X) = X6 + 1 by g(X) = X4 + X3 + X + 1. Verify the result by multiplying the quotient by g(X) to recover f(X).
Let m1(t) and m2(t) be message signals and let s1(t) and s2(t) be the corresponding modulated signals using a carrier frequency of fc.a. Show that if simple AM modulation is used, then m1(t) + m2(t) produces a modulated signal equal that is a linear combination of s1(t) and s2(t). This is why AM is
Consider the angle-modulated signal s(t) = 10 cos [2p(106)t + 0.1 sin (103)pt]a. Express s(t) as a PM signal with np = 10.b. Express s(t) as an FM signal with nf = 10 π.
Consider the angle-modulated signal s(t) = 10 cos [(108)pt + 5 sin 2p(103)t]Find the maximum phase deviation and the maximum frequency deviation.
Explain the significance of the parameter a in ARQ performance.
What is the difference between a parity-check matrix code and an LDPC code?
What function is performed by the matrices H and G in a parity-check matrix code?
In an (n, k) block ECC, what do n and k represent?
Is it possible to design an ECC that will correct some double-bit errors but not all double-bit errors? Why or why not?
What are the differences among angle modulation, PM, and FM?
TCP mandates that both the receiver and the sender should incorporate mechanisms to cope with SWS.a. Suggest a strategy for the receiver. Hint: Let the receiver “lie” about how much buffer space is available under certain circumstances. State a reasonable rule of thumb for this.b. Suggest a
A poor implementation of TCP’s sliding-window scheme can lead to extremely poor performance. There is a phenomenon known as the Silly Window Syndrome (SWS), which can easily cause degradation in performance by several factors of 10. As an example of SWS, consider an application that is engaged in
A host is receiving data from a remote peer by means of TCP segments with a payload of 1460 bytes. If TCP acknowledges every other segment, what is the minimum uplink bandwidth needed to achieve a data throughput of 1 Mbytes per second, assuming there is no overhead below the network layer? (Note:
Suppose two hosts are connected with each other by means of a 100-Mbps link, and assume the round-trip time between them is 1 ms. What is the minimum TCP window size that would let TCP achieve the maximum possible throughput between these two hosts? (Note: Assume no overhead.)
Suppose the round-trip time (RTT) between two hosts is 100 ms, and that both hosts use a TCP window of 32 Kbytes. What is the maximum throughput that can be achieved by means of TCP in this scenario?
Ordinarily, the Window field in the TCP header gives a credit allocation in octets.When the Window Scale option is in use, the value in the Window field is multiplied by a 2F, where F is the value of the window scale option. The maximum value of F that TCP accepts is 14. Why is the option limited
In discussing connection termination with reference to Figure 15.8, it was stated that in addition to receiving an acknowledgement of its FIN and sending an acknowledgement of the incoming FIN, a TCP entity must wait an interval equal to twice the maximum expected segment lifetime (the TIME WAIT
What happens in Figure 15.3 if a SYN comes in while the requested user is in CLOSED? Is there any way to get the attention of the user when it is not listening?
In a credit flow control scheme such as that of TCP, what provision could be made for credit allocations that are lost or misordered in transit?
Listed are four strategies that can be used to provide a transport user with the address of the destination transport user. For each one, describe an analogy with the Postal Service user.a. Know the address ahead of time.b. Make use of a “well-known address.”c. Use a name server.d. Addressee is
Is a deadlock possible using only a two-way handshake instead of a three-way handshake?Give an example or prove otherwise.
In a network that has a maximum packet size of 128 bytes, a maximum packet lifetime of 30 s, and an 8-bit packet sequence number, what is the maximum data rate per connection?
Consider a transport protocol that uses a connection-oriented network service.Suppose that the transport protocol uses a credit allocation flow control scheme, and the network protocol uses a sliding-window scheme. What relationship, if any, should there be between the dynamic window of the
The discussion of retransmission strategy made reference to three problems associated with dynamic timer calculation. What modifications to the strategy would help to alleviate those problems?
Consider a connection-oriented network service that suffers a reset. How could this be dealt with by a transport protocol that assumes that the network service is reliable except for resets?
With a reliable sequencing network service, are segment sequence numbers strictly necessary? What, if any, capability is lost without them?
Draw diagrams similar to Figure 15.4 for the following (assume a reliable sequenced network service):a. Connection termination: active/passiveb. Connection termination: active/activec. Connection rejectiond. Connection abortion: User issues an OPEN to a listening user, and then issues a CLOSE
Someone posting to comp.protocols.tcp-ip complained about a throughput of 122 kbps on a 256-kbps link with a 128-ms round-trip delay between the United States and Japan, and a throughput of 33 kbps when the link was routed over a satellite.a. What is the utilization over the two links? Assume a
Two transport entities communicate across a reliable network. Let the normalized time to transmit a segment equal 1. Assume that the end-to-end propagation delay is 3, and that it takes a time 2 to deliver data from a received segment to the transport user. The sender is initially granted a credit
The discussion of flow control with a reliable network service referred to a backpressure mechanism utilizing a lower-level flow control protocol. Discuss the disadvantages of this strategy.
It is common practice in most transport protocols (indeed, most protocols at all levels)for control and data to be multiplexed over the same logical channel on a per-userconnection basis. An alternative is to establish a single control transport connection between each pair of communicating
What does UDP provide that is not provided by IP?
What is a TCP implementation policy option?
Define the urgent and push features of TCP.
What is the benefit of the three-way handshake mechanism?
Explain the two-way and three-way handshake mechanisms.
What is the key difference between the TCP credit scheme and the sliding-window flow control scheme used by many other protocols, such as HDLC?
Briefly describe the credit scheme used by TCP for flow control.
Explain the use of multiplexing in the context of a transport protocol.
Describe four strategies by which a sending TS user can learn the address of a receiving TS user.
What addressing elements are needed to specify a target transport service (TS) user?
The original IPv6 specifications combined the Traffic class and Flow Label fields into a single 28-bit Flow Label field. This allowed flows to redefine the interpretation of different values of priority. Suggest reasons why the final specification includes the Priority field as a distinct field.
The question arises as to which packets generated by a source should carry nonzero IPv6 flow labels. For some applications, the answer is obvious. Small exchanges of data should have a zero flow label because it is not worth creating a flow for a few packets. Real-time flows should have a flow
The IPv6 flow mechanism assumes that the state associated with a given flow label is stored in routers, so they know how to handle packets that carry that flow label.A design requirement is to flush flow labels that are no longer being used (stale flow label) from routers.a. Assume that a source
The IPv6 standard states that if a packet with a nonzero flow label arrives at a router and the router has no information for that flow label, the router should ignore the flow label and forward the packet.a. What are the disadvantages of treating this event as an error, discarding the packet, and
Justify the recommended order in which IPv6 extension headers appear (i.e., why is the Hop-by-Hop Options header first, why is the Routing header before the Fragment header, and so on).
Compare the individual fields of the IPv4 header with the IPv6 header. Account for the functionality provided by each IPv4 field by showing how the same functionality is provided in IPv6.
In contemporary routing and addressing, the notation commonly used is called classless interdomain routing or CIDR. With CIDR, the number of bits in the mask is indicated in the following fashion: 192.168.100.0/24. This corresponds to a mask of 255.255.255.0. If this example would provide for 256
Given a company with six individual departments and each department having ten computers or networked devices, what mask could be applied to the company network to provide the subnetting necessary to divide up the network equally?
Given a network address of 192.168.100.0 and a subnet mask of 255.255.255.192,a. How many subnets are created?b. How many hosts are there per subnet?
Is the subnet mask 255.255.0.255 valid for a Class A address?
What is the difference between the subnet mask for a Class A address with 16 bits for the subnet ID and a Class B address with 8 bits for the subnet ID?
Should internetworking be concerned with a network’s internal routing? Why or why not?
is to be used. What functions could be added to the routers to alleviate some of the problems caused by the mismatched local and long-haul networks?
The architecture suggested by Figure
A transport layer message consisting of 1500 bits of data and 160 bits of header is sent to an internet layer, which appends another 160 bits of header. This is then transmitted through two networks, each of which uses a 24-bit packet header. The destination network has a maximum packet size of 800
An IP datagram is to be fragmented. Which options in the option field need to be copied into the header of each fragment, and which need only be retained in the first fragment? Justify the handling of each option.
The IP checksum needs to be recalculated at routers because of changes to the IP header, such as the lifetime field. It is possible to recalculate the checksum from scratch. Suggest a procedure that involves less calculation. Hint: Suppose that the value in 16-bit word k is changed by Z = new_value
Consider a header that consists of 10 octets, with the checksum in the last two octets(this does not correspond to any actual header format) with the following content (in hexadecimal): 01 00 F6 F7 F4 F5 F2 03 00 00a. Calculate the checksum. Show your calculations.b. Show the resulting packet.c.
A 4480-octet datagram is to be transmitted and needs to be fragmented because it will pass through an Ethernet with a maximum payload of 1500 octets. Show the Total Length, More Flag, and Fragment Offset values in each of the resulting fragments.
Because of fragmentation, an IP datagram can arrive in several pieces, not necessarily in the correct order. The IP entity at the receiving end system must accumulate these fragments until the original datagram is reconstituted.a. Consider that the IP entity creates a buffer for assembling the data
Describe some circumstances where it might be desirable to use source routing rather than let the routers make the routing decision.
What is the header overhead in the IP protocol?
In the discussion of IP, it was mentioned that the identifier, don’t fragment identifier, and time to live parameters are present in the Send primitive but not in the Deliver primitive because they are only of concern to IP. For each of these parameters indicate whether it is of concern to the IP
Although not explicitly stated, the Internet Protocol (IP) specification, RFC 791, defines the minimum packet size a network technology must support to allow IP to run over it.a. Read Section 3.2 of RFC 791 to find out that value. What is it?b. Discuss the reasons for adopting that specific value.
What is the purpose of each of the IPv6 header types?
Briefly explain the three types of IPv6 addresses.
What is the difference between the Traffic class and Flow Label fields in the IPv6 header?
How is the IPv4 header checksum calculated?
Explain the function of the three flags in the IPv4 header.
What are the pros and cons of limiting reassembly to the endpoint as compared to allowing en route reassembly?
Give some reasons for using fragmentation and reassembly.
List the requirements for an internetworking facility.
Two documents related to safety concerns associated with wireless media are the FCC OET-65 Bulletin and the ANSI/IEEE C95.1-1999. Briefly describe the purpose of these documents and briefly outline the safety concerns associated with WLAN technology.
Compare and contrast wired and wireless LANs. What unique concerns must be addressed by the designer of a WLAN network?
Try this experiment: How far can you go and still be connected to your network? This will depend to a large extent on your physical environment.
Most wireless cards come with a small set of applications that can perform tasks similar to Netstumbler. Using your own client software, determine the same items you did with Netstumbler. Do they agree?
There are many free tools and applications available for helping decipher wireless networks. One of the most popular is Netstumbler. Obtain the software at www.netstumbler.com and follow the links for downloads. The site has a list of supported wireless cards. Using the Netstumbler software,
Using what you know about wired and wireless networks, draw the topology of your network.
Answer the following questions about your wireless network:a. What is the SSID?b. Who is the equipment vendor?c. What standard are you using?d. What is the size of the network?
Show the locations of the FCS field in Figure 13.11.
The 802.11a and 802.11b physical layers make use of data scrambling (see Appendix 12B). For 802.11, the scrambling equation is P(X) = 1 + X4 + X7 In this case the shift register consists of seven elements, used in the same manner as the five-element register in Figure 12.17. For the 802.11
For IEEE 802.11a, show how the modulation technique and coding rate determine the data rate.
Consider the sequence of actions within a BSS depicted in Figure 13.14. Draw a timeline, beginning with a period during which the medium is busy and ending with a period in which the CF-End is broadcast from the AP. Show the transmission periods and the gaps.
What is the difference between an access point and a portal?
Draw a figure similar to Figure 12.16 for the MLT-3 scrambler and descrambler.
a. Verify that the division illustrated in Figure 12.18a corresponds to the implementation of Figure 12.17a by calculating the result step by step using Equation (12.1).b. Verify that the multiplication illustrated in Figure 12.18b corresponds to the implementation of Figure 12.17b by calculating
For the bit stream 0101110, sketch the waveforms for NRZ-L, NRZI, Manchester, and differential Manchester, and MLT-3.
Draw the MLT decoder state diagram that corresponds to the encoder state diagram of Figure 12.12.
With 8B6T coding, the DC algorithm sometimes negates all of the ternary symbols in a code group. How does the receiver recognize this condition? How does the receiver discriminate between a negated code group and one that has not been negated? For example, the code group for data byte 00 is + - 0 0

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Data And Computer Communications 10th Edition William Stallings - Solutions

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